BIOCHEMISTRY - DNA;RNA

Choose the best answer:

1. ____Semi-conservative replication means that:

A. DNA is copied by a conserved mechanism to ensure the few mutations occur

B. The newly made DNA double helix consists of two new DNA strands, while the

    parental DNA retains the two original strands

C. The two resulting DNA copies each have one strand of parental DNA, and

     one newly constructed strand

D. The copied DNA is almost identical to the original DNA

2. ____A replication fork is:

A. an area where the DNA separates into two strands and new DNA synthesis occurs

B. a molecular utensil required to stab nucleotides needed for DNA synthesis

C. the point when the cell must decide whether to replicate its DNA

D. a “factory” made of many enzymes that bind DNA for replication

 3. ____ The antiparallell nature of the double-stranded DNA means that:

A. the two strands run from 5’ to 3’ in opposite directions

B. the 5’ ends of the two strands are on the same ends of the DNA molecule

C. the two DNA strands twist around each other in a helical pattern

D. the 3’ ends of the two strands are on the same ends of the DNA molecule

4. ____True of the lagging strand:

A. is synthesized as one continuous strand, making it lag behind the other strand, which is

     made in many pieces at once

B. is synthesized as a series of Okasaki fragments

C. is more heavily coated with SSB proteins, slowing down synthesis

D. is synthesized more slowly due to the presence of the sliding clamp

5. ____ RNAase H aids DNA replication by:

A. removing RNA primers so that they can be resued

B. creating RNA primers for DNA polymerase to extend

C. degrading RNA bound to a DNA template

D. turning RNA into DNA

6. ____In the factory model of DNA replication:

A. DNA moves through a complex of stationary DNA-replicating enzymes

B. the “factory” of DNA-replicating enzymes moves along the DNA like a train on a railroad track

C. DNA is the only critical commodity produced by the cell

D. DNA replication enzymes are compared to a factory because they continuously produce new DNA for the cell

7. ____If one strand of a DNA molecule has the base sequence ATTGCAT, its complementary strand will have the sequence:

A. ATTGCAT      B. TAACGTA      C. GCCATGC      D. CGGTACG

 

8. ____DNA is made up of building blocks called:

 A. proteins        B. bases        C. nucleotides        D. deoxyribose

9. ____X-ray diffraction experiments conducted by _____________ led to the determination of the structure of DNA:

A. Francis Crick      B. James Watson      C. Erwin Chargaff      D. Rosalind Franklin

10. ____Meselson and Stahl proved that

A.  DNA is the genetic materia

B.  DNA is made from nucleotides

C.  DNA replicates in a semiconservative manner

D.  DNA is a double helix held together with base-pairing

  

11. ____DNA polymerase III can only add nucleotides to an existing chain, so _________________ is required.

A. an RNA primer      B. DNA polymerase I      C. helicase      D. a DNA primer

12. ____Okazaki fragments are:

A.  synthesized in the 3' to 5' direction           C. found on the leading strand     

B.  found on the lagging strand                      D. assembled as continuous replication

13.____Which of the following is NOT TRUE about replication?

A. utilizes ssDNA as template for DNA synthesis

B. catalyzed by DNA directed DNA polymerase

C. requires RNA primer to initiate the process

D. happens in the cytosol

14.____Semi-conservative replication involves this:

A. synthesizing an entirely new double helix using the old double helix as the template

B. the resulting strands will be mixtures of the old and new DNA material

C. each parent strand of DNA serves as template for the synthesis of a new strand

D. the new DNA strand would contain none of the original DNA

15.____All of the following happened during the pre-priming stage of replication EXCEPT:

A. rep proteins binding to DNA forcing the 2 strands apart

B. DNA swivelase introducing negative supertwisting

C. helix destabilizing proteins prevent reannealing

D. hydrogen bonds between base pairs are cleaved

16.____TRUE of polymerization process of replication:

A. catalyzed by DNA Pol III_α

B. it is bidirectional – either in a 5’à 3’ or 3’ à 5’ direction

C. is inhibited by 2’ deoxy nucleoside triphosphate

D. involves the incorporation of a nucleoside triphosphate into the growing  DNA strand

17.____This  function of DNA Pol I makes it capable of nick translation:

A. 5’ à 3’ polymerization                          C. 5’ à 3’ exonuclease activity

B. 3’ à 5’ exonuclease activity                 D. repair function

18.____This inhibitor of DNA replication binds to the DNA by intercalation:

A. novobiocin      B. actinomycin D       C. ara – A      D. nalidixic acid

19.____Timing of initiation of replication involves all of the following EXCEPT:

A. synthesis of RNA primer on the leading strand by primase

B. methylation of  ori C by DAM methylase

C. sequestration of nonmethylated strand of DNA in the bacterial plasma membrane

D. activation of DNA protein A by phosphorylation

20. ___What is one of the common DNA sequences recognized by a promoter?

A. TATA          B. ATAT          C. CAGCAG          D. GAAT

21. ___What is the purpose of poly A tail?

A. to whip mRNA out of the nucleus

B. to show the ribosome where to begin translation

C. to protect the mRNA strand from action of endonucleases

D. to facilitate mRNA modification

22. ___What changes does pre-mRNA undergo during post transcriptional splicing?

A. it gets longer                                 C. sequence of introns and exons rearranged

B. becomes shorter                       D. exons are cleaved and degraded

23. ___Which mRNA sequences exit the nucleus after the post transcriptional modification?

A. introns                                             C. exons

B. long terminal repeats                         D. short tandem repeats            

24. ___Given this strand of DNA, which is the corresponding pre-mRNA strand?

        T A G A C T T G A T C C A A G

A. AUCUGAACUAGGUUC               C. GCUGAGGUCGAAGGU

B. ATCTGAACTAGGTTC                   D. CAAGGUACAAGUCAA

25.____Synthesis of primary RNA transcript:

A. happens in the cytosol

B. utilizes the coding strand of the DNA as template

C. requires RNA primer to initiate its synthesis

D. is initiated with the sigma subunit of RNA polymerase recognizing the promoter sites on the template DNA strand

26.____In the prokaryotes, the first base to be transcribed:

A. is usually a pyrimidine base

B. is about 5 to 10 bases downstream of the Pribnow Box

C. is 25 bases downstream of the  TATA Box

D. is found upstream of the CAAT Box

27.____TRUE of termination of transcription:

A. when the DNA polymerase hits another RNA primer

B. pallindromic sequences seen at the 3’ end of the DNA  template

C. sequence of low G-C near the loop

D. presence of rho protein

28.____RNA polymerase  differs from DNA polymerase in that the FORMER:

A. binds to the DNA template and causes a localized melting  of dsDNA

B. requires a prepriming phase

C. has exonuclease and endonuclease activity

D. brings about polymerization only in a 5’à 3’ direction

29.____All of the following are post-transcriptional events in the eukaryotic mRNA EXCEPT FOR:

A. addition of a 7 methyl guanosine cap at the 5’ end

B. addition of polyadenylic acid tail

C. synthesis of nucleotide sequences that will be incorporated in the RNA

D. splicing of introns

TRUE OR FALSE

Use the table above to answer the following questions (numbers 27 – 36); write True if the statement is correct, write False is the statement is incorrect on the space provided each numbered statements.

T ---30. _____ Some amino acids are coded by more than one codon.

F--- 31. _____ All amino acids are coded by more than one codon.

F ---32. _____ Proteins can start with any amino acid.

T ---33. _____ Codons are located on the mRNA.

F ---34. _____ Only one codon indicates the end of a protein.

F ---35. _____ Anticodons neutralize codons so theyf cannot function properly.

T ---36. _____ Only one codon indicates the start of a protein.

T ---37. _____ When multiple codons code for the same amino acid, the first two

      bases of  the codon are usually the same.

T ---38. _____ The STOP codons are UAA, UGA, and UAG.

T ---39. _____ Every AUG codon indicates the start of a protein.

From what you know of the genetic code, fill in the numbered blanks (numbers 40 – 45) in the following table:

Amino acid	Met	40.      Serine	41.    Isoleucine
Codon	42.          AUG	UCA	43.    AUC
Anticodon	44.          UAC	45.      AGU	UAG

Choose the best answer:

46.  ___With what mRNA codon would the tRNA with anticodon “3’-UAC5’ be able to form a codon-anticodon base pairing interaction? 

A. 5'-GUA-3'       B. 5'-AUG-3'          C. 5'-UAC-3'           D. 5'-CAU-3'

47., 48., 49. ___Three types of RNA involved in comprising the structural and functional core for protein synthesis, serving as a template for translation, and transporting amino acid, respectively, are:

A. mRNA, tRNA, rRNA                          C. rRNA, mRNA , tRNA

B. rRNA, tRNA, mRNA                          D. tRNA, mRNA, rRNA

50. ___A messenger RNA is 333 nucleotides long, including the initiator and termination codons. The number of amino acids in the protein translated from this mRNA is:

A. 999          B. 630          C. 111          D. 110

51. ___What step essential for correct translation of the genetic code occurs during amino acid activation?

A. codon-anticodon base pairing

B. copying of the DNA template strand

C. recognition of the initiator tRNA at the P-site of the ribosome

D. attachment of an amino acid to the correct tRNA

52, 53. ____ During the elongation phase of protein synthesis, the growing peptide chain is attached to the tRNA in the ______________, and the incoming tRNA first base pairs with the mRNA at the ______________.

A. P-site, A-site                          C. P-site, aminoacyl tRNA synthetase

B. A-site, P-site                          D. peptidyl transferase, P-site

54.____This portion of the tRNA recognizes the triplet codon carried by the mRNA:

A. anticodon arm      B. extra arm      C. DHU arm      D. variable arm

55.____This Type I antibiotics bind to beta subunit of RNA polymeerase and inhibits progressive elongation after initiation of the chain:

A. Rifamycin      B. Streptolydigin      C. Actinomycin D      D. Coumermycin

56.____The degeneracy of the genetic code means :

A. only one amino acid is being specified by one triplet codon

B. it is universally used  by both plants and animals

C. one amino acid could have several triplet codons

D. nucleotide sequences are read continuously and grouped by threes in the form of triplet codon

57.____TRUE of charging of the RNA:

A. leads to formation of an aminoacyl-AMP complex followed by transfer of aminoacyl group to tRNA

B. requires energy supplied by GTP

C. catalyzed by aminoacyl mRNA synthetase

D. amino acid added to the 3’ end of the mRNA

58.____ All of the following energy requiring steps utilize  GTP EXCEPT FOR THIS STEP:

 A. Binding of initiator tRNA to P site                         C. charging of the tRNA    

 B. binding of incoming  tRNA  to A site                     D. translocation process

59.____Initiation of translation requires this step:

A. IF-1 is responsible for binding of initiator tRNA  to 30S ribosomal subunit

B. base pairing of nucleotide sequences  in the Shine Dalgarno sequence with the 16 S ribosomal subunit in prokaryotes

C. recognition of Hogness Box

D. addition of 5’cap to the mRNA

60.____ In Eukaryotes, the joining of the 40S initiation complex to 60S is facilitated by this:  

A.  eIF 2a        B.  eIF 3        C. eIF 5        D.  eIF 6

61.____TRUE OF eukaryotic translation:

A. transcription has to be done before translation can be initiated

B. transcription and translation can happen simultaneously

C. gene control is done at the level of transcription

D. happens in the nucleus

62.____Inhibitor of prokaryotic translation that inhibits the binding of the aminoacyl tRNA to A site:   A. Chloramphenicol                       C. erythromycin

         B. tetracycline                                 D. ricin and abrin

Problems on the Genetic Code. Answer numbers 63 –65, using the genetic code.

 63. ___ Based on information provided in the Genetic Code Table, predict which mRNA sequence would have the information for the synthesis of a short peptide of sequence (amino terminus) MET-TYR-PRO-CYS-STOP (carboxyl terminus).

A. A. 3'- CAU CAA GGG GCU AUC                C. 5'- AUG UAC CCC UGU UAA

B. 5'- CUA AAC GGG UCG CUA                    D. 5'- UUA ACA GGG GUA CAU

64. ___ A synthetic mRNA of repeating sequence 5'-GACGACGACGACGACGAC... is used for a cell-free protein synthesizing system like the one used by Niremberg. If we assume that protein synthesis can begin without the need for an initiator codon, what product or products would you expect to occur after protein synthesis.

A. one protein, consisting of a single amino acid

B. three proteins, each consisting of a different, single amino acid

C. two proteins, each with an alternating sequence of two different amino acids

D. one protein, with an alternating sequence of three different amino acids

65. ___ What protein sequence is encoded by a mRNA sequence of (by the following RNA sequence) 5'-....CGC GCG CGC GCG CGC GCG CGC GCG...

A. ...Arg-Ala-Arg-Ala-Arg-Ala-Arg-Ala...

B. ...Arg-Arg-Arg-Arg-Arg-Arg-Arg-Arg...

C. ...Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala...

D. Both ...Arg-Arg-Arg-Arg-Arg-Arg-Arg-Arg... and ...Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala...

66. ___ After amino acid activitation, which amino acid would be attached to a tRNA with the anticodon 5'-UAC-3'?

A. PHE          B. LEU          C. ILE          D. MET

67. ___ A(n) _______________ is a piece of DNA with a group of genes that are transcribed together as a unit.

A. promoter          B. repressor          C. operator          D. operon

68. ___ What effect would the addition of lactose have on a repressed lac operon?

A The operator site on the operon would move.

B It would reinforce the repression of that gene.

C The lac operon would be transcribed.

D It would have no effect whatsoever.

69, 70, 71. ___ In the (absence, presence) of lactose, the lac ______________ binds to the lac ____________ site.

A. presence, operator, repressor                   C. absence, operator, repressor

B. presence, repressor, promoter                  D. absence, repressor, operator

72. ___ Which statement characterizes the lac operon?

A. its a repressible system                C. its a constitutive system

B. its an inducible system                 D. none of the choices

73. ___ If lactose-metabolizing enzymes are produced whether or not lactose is present, a mutation in which gene is the likely cause?

A. lac Z(encodes β-galactosidase                            

B. lac Y(encodes β-galactoside permease)

C. lac A(encodes β-galactoside transacetylase)     

D. lac I (encodes the lac repressor protein)

74. ___ True of lac operon, EXCEPT:

A. a catabolite gene activator protein forms a complex with cAMP to enhance transcription of genes

B. high glucose level will decrease CAP-cAMP complex

C. allolactose serves as co-repressor in the operon

D. with low lactose levels-repressor binds to operator site and inhibits transcription of structural genes

75. ___ The trp operon is an example of what kind of system?

A. repressible                                             C. inducible                                

B. constitutive                                             D. none of the choices

76. ___ In the absence of tryptophan, what is the state of the repressor protein?

A. repressor protein is active                           C. repressor protein is inactive

B. repressor protein is not expressed               D. none of the choices

77.____TRUE of repressors EXCEPT:

A. synthesized by promoter genes

B. bind to the operator site of the DNA template

C. inhibits transcription of structural genes

D. their effects can be reversed by the addition of an inducer molecule

78.____Which of the following statements IS NOT TRUE about the TRP Operon:

A. TRP serves as a co-repressor

B. an attenuator sequence controls the length of the mRNA transcribed

C. regulation is done only in the initiation of transcription

D. controls the synthesis of tryptophan

79.____TRUE of  protein synthesis in reticulocytes:

A. heme stimulates adenylate cyclase activitgy

B. eIF-2 is rendered inactive

C. is a typical example of gene regulation

D.adequate supply of heme will ensure the production of globin

Match the enzyme with its function:

80. ____polymerase (E)                                 A. links short DNA chains    

81. ____helicase ( F)                                     B. prevents reannealing

82. ____ligase (A)                                          C. creates RNA primers

83. ____primase (C)                                      D. helps hold polymerase on DNA

84. ____RNAse H(G)                                     E. extends DNA chain

85. ____sliding clamp (D)                              F. separates DNA strands

86. ____SSB (B)                                            G. removes RNA primers

87. ___ A microlesion type of mutation wherein a purine base is replaced by a

pyrimidine base.

A. transition       B. transversion        C. silent        D. deletion

88. ___ A base substitution type of mutation wherein the codon is changed to a

stop codon.

A. silent       B. missense        C.  nonsense        D. spontaneous

89. ___ Causes of spontaneous mutation, EXCEPT.

A. palindromic misalignment           C. transposons

B. tautomeric base mispairs            D. alternating sequence misalignment

90. ___ Indirect effects of ionizing radiation are mediated through:

A. energy transfer to biomolecules     C. diffusible radicals

B. primary lesions                               D. molecular alterations

91. ___ The base most sensitive to effects of ionizing radiations:

A. guanine        B. thymine        C. adenine        D. cytosine

92. ___ An intercalating agent:

A. aflatoxin        B. DMN        C. benzo(a)pyrene        D. trp-p2

93. ___ Part of guanine base most sensitive to alkylating agents:

A. oxygen 6       B. exo-NH₂       C. nitrogen 3        D. nitrogen 7

94. ___ Which statement about transcription is correct?

A. the non-template strand is read in a 3'-to-5' direction.

B. the template strand is read in a 5'-to-3' direction.

C. an RNA is transcribed in the 3'-to-5' direction.

D. an RNA is transcribed in the 5'-to-3' direction.

95. ___ Which three statements below are correct?

A. Both prokaryotic and eukaryotic mRNAs have a 5' cap.

B. Only prokaryotic mRNAs are polyadenylated at the 3' end.

C. In prokaryotes, transcription is coupled to translation.
D. In eukaryotes, RNA splicing occurs after the mRNA is transported into the cytoplasm.

96. ___ What effect would a mutation in an intron section of a gene have on the expression of the gene?
A. will have no effect on gene expression

B. introns are cut out of the mRNA transcript before translation

C. will lead to over gene expression

D. will lead to under expression of gene

97. ___ Which of the following illustrates a missense mutation?

A. GAG àAAG      B. GAG ->GAC       C. GAG ->GAA      D. GAG ->UAG

98. ___ A particular gene sequence GAG CCT ATA AGC TCG was exposed to a potent chemical mutagen that brought about transition in one of the base pairs.  Which mutated sequence will show this effect:

A. GAG CCC ATA AGC TCG            C. GAG CCT ATA AGG TCG

B. GAG CCT ATA AGC TGG            D. GTG CCT ATA AGC TCG

99. ___ The protein product of a gene that is affected by a silent mutation is:

A. incomplete and non-functional

B. abnormal in structure but functional   

C. normal in structure but non-functional

D. normal in  structure and function

100. ___ Which chemical mutagen interferes with the stacking interactions between base pairs of DNA thus causing distortion of the double helix:

A. dimethylnitrosamine                            C. nitrous acid

B. ethidium bromide                                 D. 5-fluorouracil

101. ___ The most commonly involved site on a nitrogenous base when the DNA is exposed to an alkylating substance is:

A. O2 of thymine        B. O4 of thymine      C. N3 of adenine      D. N7 of guanine

102. ___ Exposure of the DNA molecule to UV radiation deforms the DNA double helix by:

A. breaking the phosphodiester backbone

B. creating thymine-thymine dimers             

C. deaminating cytosine to uracil

D. directly damaging the hydrogen bonds

103. ___ In order for DNA repair to guarantee that permanent mutagenic change is prevented, it should occur:

A. before the next replication of DNA

B. after copying the gene into mRNA        

C. immediately following protein synthesis

D. during transcription

104. ___ A form of DNA damage reversal in which methylated bases in DNA are removed by glycosylases is the:

A. excision repair mechanism            C. SOS repair network

B. photoreactivating system               D. photoreactivating system

105. ___ Recombinational repair of damaged DNA is characterized by:

A. patching of the cut damaged DNA fragment

B. removal of the damaged DNA segment

C. cleavage of the phosphodiester backbone of the damaged sequence

D.”sister-strand exchange” with a homologous DNA segment

Nucleotide Metabolism questions:

Choose the best answer:

 1. ___The compound utilized to elucidate the reactions of the de novo purine nucleotide synthesis:    A. urate      B. uridylate      C. adenylate      D. guanylate

2. ___The enzyme that catalyzes the rate limiting step of purine nucleotide de novo synthesis:

A. pyrophosphokinase                                       C. GAR synthetase

B. amidophosphoribosyltransferase                  D. GAR transformylase

3. An important characteristic of the rate limiting step of purine nucleotide de novo synthesis:

A. a revesible step

B. the step subjected to the most regulation                    

C. has not bearing on the future anomeric configuration of future nucleotides

D. does not need hydrolysis of high energy phosphate 

4. ___The first atom acquired in the process of purine nucleotide de novo synthesis:

A. N₇            B. N₁           C. N₉            D. N₃

5. ___The bond created with the acquisition of the first atom in the de novo synthesis of purine nucleotides:

A. O-glycosidic bond                           C. amide bond

B. N-glycosidic bond                           D. phosphoester bond

6. ___The anomeric configuration of the first purine nucleotide synthesized:

A. alpha      B. beta      C. L configuration      D. D configuration

7. ___The rate limiting step of purine nucleotide de novo synthesis is made irreversible by:

A. displacement of NH₂ group            C. hydrolysis of ATP

B. liberation of glutamate                    D. hydrolysis of PPi

8. ___The reaction catalyzed by GAR synthetase in the presence of glycine is unique because:

A. the only step in de novo synthesis wherein more than one atom is acquired

B. it is a flux generating step

C. irreversible

D. ATP hydrolysis drives the reaction to completion

9. ___In GAR synthetase reaction, these atoms are acquired in the presence of glycine:

A. C₆, C₂ & N₇      B. C₄, C₅ & N₇      C. C₂, C₈ & N₉      D. C_4, C₈ & N₃

10. ___The form of tetrahydrofolate from which C₂ of purine ring is derived by the cells:

A. N⁵ N¹⁰ methylene THF                  C. formimino THF

B. N¹⁰ formyl THF                              D. methyl THF

11. ___The fumarate portion of aspartate enters the Kreb’s cycle thru this intermediate:

A. fumarate      B. succinyl CoA      C. oxaloacetate      D. α keto glutarate

12. ___The first purine nucleotide generated in de novo synthesis:

A. AMP           B. GMP           C. XMP           D. IMP

13. ___The energy utilized by adenylosuccinate synthetase enzyme to synthesize AMP from IMP:

 A. ATP           B. CTP            C. GTP            D. UTP

14.  ___Lesh-Nyhan syndrome is caused by a deficiency of this enzyme:

A. hypoxanthine-guanine phosphoribolsyl transferase

B. adenine phosphoribosyl transferase

C. thymidine kinase

D. uridine-cytidine kinase

15. ___In eukaryotes the rate limiting step for pyrimidine nucleotide de novo pathway is catalyzed by:

A. carbamoyl PO₄ synthetase I            C. aspartate transcarbamoylase

B. carbamoyl PO₄ synthetase II        D. dihydroorotase

16. ___The source of nitrogen for the rate limiting step of pyrimidine nucleotide de novo pathway:   A. ammonia      B. amide of D      C. amide of E      D. amino of E

17. ___Which atom of pyrimidine bases is also found in purine bases and shares the same origin, aspartate?      A. N₃             B. N₁             C. N₇              D. N₉

18. ___The first pyrimidine nucleotide generagted in its synthesis:

 A. OMP         B. UMP         C. CMP         D. TMP

19. ___The source of the electrons and protons for the synthesis of deoxynuycleotides:

A. thioredoxin (oxidized)                   C. NADPH + H

B. thioredoxin (reduced)                   D. NADH + H

20. ___The mitochondrial enzyme of pyrimidine nucleotide de novo synthesis:

A. dihydrooratoase                                      C. orotate phosphoribosyl transferase

B. dihydroorotate dehydrogenase           D. aspartate transcarbamoylase

21. ___The final product of purine nucleotide Choose the best answer:

1. ____Semi-conservative replication means that:

A. DNA is copied by a conserved mechanism to ensure the few mutations occur

B. The newly made DNA double helix consists of two new DNA strands, while the

    parental DNA retains the two original strands

C. The two resulting DNA copies each have one strand of parental DNA, and

     one newly constructed strand

D. The copied DNA is almost identical to the original DNA

2. ____A replication fork is:

A. an area where the DNA separates into two strands and new DNA synthesis occurs

B. a molecular utensil required to stab nucleotides needed for DNA synthesis

C. the point when the cell must decide whether to replicate its DNA

D. a “factory” made of many enzymes that bind DNA for replication

 3. ____ The antiparallell nature of the double-stranded DNA means that:

A. the two strands run from 5’ to 3’ in opposite directions

B. the 5’ ends of the two strands are on the same ends of the DNA molecule

C. the two DNA strands twist around each other in a helical pattern

D. the 3’ ends of the two strands are on the same ends of the DNA molecule

4. ____True of the lagging strand:

A. is synthesized as one continuous strand, making it lag behind the other strand, which is

     made in many pieces at once

B. is synthesized as a series of Okasaki fragments

C. is more heavily coated with SSB proteins, slowing down synthesis

D. is synthesized more slowly due to the presence of the sliding clamp

5. ____ RNAase H aids DNA replication by:

A. removing RNA primers so that they can be resued

B. creating RNA primers for DNA polymerase to extend

C. degrading RNA bound to a DNA template

D. turning RNA into DNA

6. ____In the factory model of DNA replication:

A. DNA moves through a complex of stationary DNA-replicating enzymes

B. the “factory” of DNA-replicating enzymes moves along the DNA like a train on a railroad track

C. DNA is the only critical commodity produced by the cell

D. DNA replication enzymes are compared to a factory because they continuously produce new DNA for the cell

7. ____If one strand of a DNA molecule has the base sequence ATTGCAT, its complementary strand will have the sequence:

A. ATTGCAT      B. TAACGTA      C. GCCATGC      D. CGGTACG

 

8. ____DNA is made up of building blocks called:

 A. proteins        B. bases        C. nucleotides        D. deoxyribose

9. ____X-ray diffraction experiments conducted by _____________ led to the determination of the structure of DNA:

A. Francis Crick      B. James Watson      C. Erwin Chargaff      D. Rosalind Franklin

10. ____Meselson and Stahl proved that

A.  DNA is the genetic materia

B.  DNA is made from nucleotides

C.  DNA replicates in a semiconservative manner

D.  DNA is a double helix held together with base-pairing

  

11. ____DNA polymerase III can only add nucleotides to an existing chain, so _________________ is required.

A. an RNA primer      B. DNA polymerase I      C. helicase      D. a DNA primer

12. ____Okazaki fragments are:

A.  synthesized in the 3' to 5' direction           C. found on the leading strand     

B.  found on the lagging strand                      D. assembled as continuous replication

13.____Which of the following is NOT TRUE about replication?

A. utilizes ssDNA as template for DNA synthesis

B. catalyzed by DNA directed DNA polymerase

C. requires RNA primer to initiate the process

D. happens in the cytosol

14.____Semi-conservative replication involves this:

A. synthesizing an entirely new double helix using the old double helix as the template

B. the resulting strands will be mixtures of the old and new DNA material

C. each parent strand of DNA serves as template for the synthesis of a new strand

D. the new DNA strand would contain none of the original DNA

15.____All of the following happened during the pre-priming stage of replication EXCEPT:

A. rep proteins binding to DNA forcing the 2 strands apart

B. DNA swivelase introducing negative supertwisting

C. helix destabilizing proteins prevent reannealing

D. hydrogen bonds between base pairs are cleaved

16.____TRUE of polymerization process of replication:

A. catalyzed by DNA Pol III_α

B. it is bidirectional – either in a 5’à 3’ or 3’ à 5’ direction

C. is inhibited by 2’ deoxy nucleoside triphosphate

D. involves the incorporation of a nucleoside triphosphate into the growing  DNA strand

17.____This  function of DNA Pol I makes it capable of nick translation:

A. 5’ à 3’ polymerization                          C. 5’ à 3’ exonuclease activity

B. 3’ à 5’ exonuclease activity                 D. repair function

18.____This inhibitor of DNA replication binds to the DNA by intercalation:

A. novobiocin      B. actinomycin D       C. ara – A      D. nalidixic acid

19.____Timing of initiation of replication involves all of the following EXCEPT:

A. synthesis of RNA primer on the leading strand by primase

B. methylation of  ori C by DAM methylase

C. sequestration of nonmethylated strand of DNA in the bacterial plasma membrane

D. activation of DNA protein A by phosphorylation

20. ___What is one of the common DNA sequences recognized by a promoter?

A. TATA          B. ATAT          C. CAGCAG          D. GAAT

21. ___What is the purpose of poly A tail?

A. to whip mRNA out of the nucleus

B. to show the ribosome where to begin translation

C. to protect the mRNA strand from action of endonucleases

D. to facilitate mRNA modification

22. ___What changes does pre-mRNA undergo during post transcriptional splicing?

A. it gets longer                                 C. sequence of introns and exons rearranged

B. becomes shorter                       D. exons are cleaved and degraded

23. ___Which mRNA sequences exit the nucleus after the post transcriptional modification?

A. introns                                             C. exons

B. long terminal repeats                         D. short tandem repeats            

24. ___Given this strand of DNA, which is the corresponding pre-mRNA strand?

        T A G A C T T G A T C C A A G

A. AUCUGAACUAGGUUC               C. GCUGAGGUCGAAGGU

B. ATCTGAACTAGGTTC                   D. CAAGGUACAAGUCAA

25.____Synthesis of primary RNA transcript:

A. happens in the cytosol

B. utilizes the coding strand of the DNA as template

C. requires RNA primer to initiate its synthesis

D. is initiated with the sigma subunit of RNA polymerase recognizing the promoter sites on the template DNA strand

26.____In the prokaryotes, the first base to be transcribed:

A. is usually a pyrimidine base

B. is about 5 to 10 bases downstream of the Pribnow Box

C. is 25 bases downstream of the  TATA Box

D. is found upstream of the CAAT Box

27.____TRUE of termination of transcription:

A. when the DNA polymerase hits another RNA primer

B. pallindromic sequences seen at the 3’ end of the DNA  template

C. sequence of low G-C near the loop

D. presence of rho protein

28.____RNA polymerase  differs from DNA polymerase in that the FORMER:

A. binds to the DNA template and causes a localized melting  of dsDNA

B. requires a prepriming phase

C. has exonuclease and endonuclease activity

D. brings about polymerization only in a 5’à 3’ direction

29.____All of the following are post-transcriptional events in the eukaryotic mRNA EXCEPT FOR:

A. addition of a 7 methyl guanosine cap at the 5’ end

B. addition of polyadenylic acid tail

C. synthesis of nucleotide sequences that will be incorporated in the RNA

D. splicing of introns

TRUE OR FALSE

Use the table above to answer the following questions (numbers 27 – 36); write True if the statement is correct, write False is the statement is incorrect on the space provided each numbered statements.

T ---30. _____ Some amino acids are coded by more than one codon.

F--- 31. _____ All amino acids are coded by more than one codon.

F ---32. _____ Proteins can start with any amino acid.

T ---33. _____ Codons are located on the mRNA.

F ---34. _____ Only one codon indicates the end of a protein.

F ---35. _____ Anticodons neutralize codons so theyf cannot function properly.

T ---36. _____ Only one codon indicates the start of a protein.

T ---37. _____ When multiple codons code for the same amino acid, the first two

      bases of  the codon are usually the same.

T ---38. _____ The STOP codons are UAA, UGA, and UAG.

T ---39. _____ Every AUG codon indicates the start of a protein.

From what you know of the genetic code, fill in the numbered blanks (numbers 40 – 45) in the following table:

Amino acid	Met	40.      Serine	41.    Isoleucine
Codon	42.          AUG	UCA	43.    AUC
Anticodon	44.          UAC	45.      AGU	UAG

Choose the best answer:

46.  ___With what mRNA codon would the tRNA with anticodon “3’-UAC5’ be able to form a codon-anticodon base pairing interaction? 

A. 5'-GUA-3'       B. 5'-AUG-3'          C. 5'-UAC-3'           D. 5'-CAU-3'

47., 48., 49. ___Three types of RNA involved in comprising the structural and functional core for protein synthesis, serving as a template for translation, and transporting amino acid, respectively, are:

A. mRNA, tRNA, rRNA                          C. rRNA, mRNA , tRNA

B. rRNA, tRNA, mRNA                          D. tRNA, mRNA, rRNA

50. ___A messenger RNA is 333 nucleotides long, including the initiator and termination codons. The number of amino acids in the protein translated from this mRNA is:

A. 999          B. 630          C. 111          D. 110

51. ___What step essential for correct translation of the genetic code occurs during amino acid activation?

A. codon-anticodon base pairing

B. copying of the DNA template strand

C. recognition of the initiator tRNA at the P-site of the ribosome

D. attachment of an amino acid to the correct tRNA

52, 53. ____ During the elongation phase of protein synthesis, the growing peptide chain is attached to the tRNA in the ______________, and the incoming tRNA first base pairs with the mRNA at the ______________.

A. P-site, A-site                          C. P-site, aminoacyl tRNA synthetase

B. A-site, P-site                          D. peptidyl transferase, P-site

54.____This portion of the tRNA recognizes the triplet codon carried by the mRNA:

A. anticodon arm      B. extra arm      C. DHU arm      D. variable arm

55.____This Type I antibiotics bind to beta subunit of RNA polymeerase and inhibits progressive elongation after initiation of the chain:

A. Rifamycin      B. Streptolydigin      C. Actinomycin D      D. Coumermycin

56.____The degeneracy of the genetic code means :

A. only one amino acid is being specified by one triplet codon

B. it is universally used  by both plants and animals

C. one amino acid could have several triplet codons

D. nucleotide sequences are read continuously and grouped by threes in the form of triplet codon

57.____TRUE of charging of the RNA:

A. leads to formation of an aminoacyl-AMP complex followed by transfer of aminoacyl group to tRNA

B. requires energy supplied by GTP

C. catalyzed by aminoacyl mRNA synthetase

D. amino acid added to the 3’ end of the mRNA

58.____ All of the following energy requiring steps utilize  GTP EXCEPT FOR THIS STEP:

 A. Binding of initiator tRNA to P site                         C. charging of the tRNA    

 B. binding of incoming  tRNA  to A site                     D. translocation process

59.____Initiation of translation requires this step:

A. IF-1 is responsible for binding of initiator tRNA  to 30S ribosomal subunit

B. base pairing of nucleotide sequences  in the Shine Dalgarno sequence with the 16 S ribosomal subunit in prokaryotes

C. recognition of Hogness Box

D. addition of 5’cap to the mRNA

60.____ In Eukaryotes, the joining of the 40S initiation complex to 60S is facilitated by this:  

A.  eIF 2a        B.  eIF 3        C. eIF 5        D.  eIF 6

61.____TRUE OF eukaryotic translation:

A. transcription has to be done before translation can be initiated

B. transcription and translation can happen simultaneously

C. gene control is done at the level of transcription

D. happens in the nucleus

62.____Inhibitor of prokaryotic translation that inhibits the binding of the aminoacyl tRNA to A site:   A. Chloramphenicol                       C. erythromycin

         B. tetracycline                                 D. ricin and abrin

Problems on the Genetic Code. Answer numbers 63 –65, using the genetic code.

 63. ___ Based on information provided in the Genetic Code Table, predict which mRNA sequence would have the information for the synthesis of a short peptide of sequence (amino terminus) MET-TYR-PRO-CYS-STOP (carboxyl terminus).

A. A. 3'- CAU CAA GGG GCU AUC                C. 5'- AUG UAC CCC UGU UAA

B. 5'- CUA AAC GGG UCG CUA                    D. 5'- UUA ACA GGG GUA CAU

64. ___ A synthetic mRNA of repeating sequence 5'-GACGACGACGACGACGAC... is used for a cell-free protein synthesizing system like the one used by Niremberg. If we assume that protein synthesis can begin without the need for an initiator codon, what product or products would you expect to occur after protein synthesis.

A. one protein, consisting of a single amino acid

B. three proteins, each consisting of a different, single amino acid

C. two proteins, each with an alternating sequence of two different amino acids

D. one protein, with an alternating sequence of three different amino acids

65. ___ What protein sequence is encoded by a mRNA sequence of (by the following RNA sequence) 5'-....CGC GCG CGC GCG CGC GCG CGC GCG...

A. ...Arg-Ala-Arg-Ala-Arg-Ala-Arg-Ala...

B. ...Arg-Arg-Arg-Arg-Arg-Arg-Arg-Arg...

C. ...Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala...

D. Both ...Arg-Arg-Arg-Arg-Arg-Arg-Arg-Arg... and ...Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala...

66. ___ After amino acid activitation, which amino acid would be attached to a tRNA with the anticodon 5'-UAC-3'?

A. PHE          B. LEU          C. ILE          D. MET

67. ___ A(n) _______________ is a piece of DNA with a group of genes that are transcribed together as a unit.

A. promoter          B. repressor          C. operator          D. operon

68. ___ What effect would the addition of lactose have on a repressed lac operon?

A The operator site on the operon would move.

B It would reinforce the repression of that gene.

C The lac operon would be transcribed.

D It would have no effect whatsoever.

69, 70, 71. ___ In the (absence, presence) of lactose, the lac ______________ binds to the lac ____________ site.

A. presence, operator, repressor                   C. absence, operator, repressor

B. presence, repressor, promoter                  D. absence, repressor, operator

72. ___ Which statement characterizes the lac operon?

A. its a repressible system                C. its a constitutive system

B. its an inducible system                 D. none of the choices

73. ___ If lactose-metabolizing enzymes are produced whether or not lactose is present, a mutation in which gene is the likely cause?

A. lac Z(encodes β-galactosidase                            

B. lac Y(encodes β-galactoside permease)

C. lac A(encodes β-galactoside transacetylase)     

D. lac I (encodes the lac repressor protein)

74. ___ True of lac operon, EXCEPT:

A. a catabolite gene activator protein forms a complex with cAMP to enhance transcription of genes

B. high glucose level will decrease CAP-cAMP complex

C. allolactose serves as co-repressor in the operon

D. with low lactose levels-repressor binds to operator site and inhibits transcription of structural genes

75. ___ The trp operon is an example of what kind of system?

A. repressible                                             C. inducible                                

B. constitutive                                             D. none of the choices

76. ___ In the absence of tryptophan, what is the state of the repressor protein?

A. repressor protein is active                           C. repressor protein is inactive

B. repressor protein is not expressed               D. none of the choices

77.____TRUE of repressors EXCEPT:

A. synthesized by promoter genes

B. bind to the operator site of the DNA template

C. inhibits transcription of structural genes

D. their effects can be reversed by the addition of an inducer molecule

78.____Which of the following statements IS NOT TRUE about the TRP Operon:

A. TRP serves as a co-repressor

B. an attenuator sequence controls the length of the mRNA transcribed

C. regulation is done only in the initiation of transcription

D. controls the synthesis of tryptophan

79.____TRUE of  protein synthesis in reticulocytes:

A. heme stimulates adenylate cyclase activitgy

B. eIF-2 is rendered inactive

C. is a typical example of gene regulation

D.adequate supply of heme will ensure the production of globin

Match the enzyme with its function:

80. ____polymerase (E)                                 A. links short DNA chains    

81. ____helicase ( F)                                     B. prevents reannealing

82. ____ligase (A)                                          C. creates RNA primers

83. ____primase (C)                                      D. helps hold polymerase on DNA

84. ____RNAse H(G)                                     E. extends DNA chain

85. ____sliding clamp (D)                              F. separates DNA strands

86. ____SSB (B)                                            G. removes RNA primers

87. ___ A microlesion type of mutation wherein a purine base is replaced by a

pyrimidine base.

A. transition       B. transversion        C. silent        D. deletion

88. ___ A base substitution type of mutation wherein the codon is changed to a

stop codon.

A. silent       B. missense        C.  nonsense        D. spontaneous

89. ___ Causes of spontaneous mutation, EXCEPT.

A. palindromic misalignment           C. transposons

B. tautomeric base mispairs            D. alternating sequence misalignment

90. ___ Indirect effects of ionizing radiation are mediated through:

A. energy transfer to biomolecules     C. diffusible radicals

B. primary lesions                               D. molecular alterations

91. ___ The base most sensitive to effects of ionizing radiations:

A. guanine        B. thymine        C. adenine        D. cytosine

92. ___ An intercalating agent:

A. aflatoxin        B. DMN        C. benzo(a)pyrene        D. trp-p2

93. ___ Part of guanine base most sensitive to alkylating agents:

A. oxygen 6       B. exo-NH₂       C. nitrogen 3        D. nitrogen 7

94. ___ Which statement about transcription is correct?

A. the non-template strand is read in a 3'-to-5' direction.

B. the template strand is read in a 5'-to-3' direction.

C. an RNA is transcribed in the 3'-to-5' direction.

D. an RNA is transcribed in the 5'-to-3' direction.

95. ___ Which three statements below are correct?

A. Both prokaryotic and eukaryotic mRNAs have a 5' cap.

B. Only prokaryotic mRNAs are polyadenylated at the 3' end.

C. In prokaryotes, transcription is coupled to translation.
D. In eukaryotes, RNA splicing occurs after the mRNA is transported into the cytoplasm.

96. ___ What effect would a mutation in an intron section of a gene have on the expression of the gene?
A. will have no effect on gene expression

B. introns are cut out of the mRNA transcript before translation

C. will lead to over gene expression

D. will lead to under expression of gene

97. ___ Which of the following illustrates a missense mutation?

A. GAG àAAG      B. GAG ->GAC       C. GAG ->GAA      D. GAG ->UAG

98. ___ A particular gene sequence GAG CCT ATA AGC TCG was exposed to a potent chemical mutagen that brought about transition in one of the base pairs.  Which mutated sequence will show this effect:

A. GAG CCC ATA AGC TCG            C. GAG CCT ATA AGG TCG

B. GAG CCT ATA AGC TGG            D. GTG CCT ATA AGC TCG

99. ___ The protein product of a gene that is affected by a silent mutation is:

A. incomplete and non-functional

B. abnormal in structure but functional   

C. normal in structure but non-functional

D. normal in  structure and function

100. ___ Which chemical mutagen interferes with the stacking interactions between base pairs of DNA thus causing distortion of the double helix:

A. dimethylnitrosamine                            C. nitrous acid

B. ethidium bromide                                 D. 5-fluorouracil

101. ___ The most commonly involved site on a nitrogenous base when the DNA is exposed to an alkylating substance is:

A. O2 of thymine        B. O4 of thymine      C. N3 of adenine      D. N7 of guanine

102. ___ Exposure of the DNA molecule to UV radiation deforms the DNA double helix by:

A. breaking the phosphodiester backbone

B. creating thymine-thymine dimers             

C. deaminating cytosine to uracil

D. directly damaging the hydrogen bonds

103. ___ In order for DNA repair to guarantee that permanent mutagenic change is prevented, it should occur:

A. before the next replication of DNA

B. after copying the gene into mRNA        

C. immediately following protein synthesis

D. during transcription

104. ___ A form of DNA damage reversal in which methylated bases in DNA are removed by glycosylases is the:

A. excision repair mechanism            C. SOS repair network

B. photoreactivating system               D. photoreactivating system

105. ___ Recombinational repair of damaged DNA is characterized by:

A. patching of the cut damaged DNA fragment

B. removal of the damaged DNA segment

C. cleavage of the phosphodiester backbone of the damaged sequence

D.”sister-strand exchange” with a homologous DNA segment

Nucleotide Metabolism questions:

Choose the best answer:

 1. ___The compound utilized to elucidate the reactions of the de novo purine nucleotide synthesis:    A. urate      B. uridylate      C. adenylate      D. guanylate

2. ___The enzyme that catalyzes the rate limiting step of purine nucleotide de novo synthesis:

A. pyrophosphokinase                                       C. GAR synthetase

B. amidophosphoribosyltransferase                  D. GAR transformylase

3. An important characteristic of the rate limiting step of purine nucleotide de novo synthesis:

A. a revesible step

B. the step subjected to the most regulation                    

C. has not bearing on the future anomeric configuration of future nucleotides

D. does not need hydrolysis of high energy phosphate 

4. ___The first atom acquired in the process of purine nucleotide de novo synthesis:

A. N₇            B. N₁           C. N₉            D. N₃

5. ___The bond created with the acquisition of the first atom in the de novo synthesis of purine nucleotides:

A. O-glycosidic bond                           C. amide bond

B. N-glycosidic bond                           D. phosphoester bond

6. ___The anomeric configuration of the first purine nucleotide synthesized:

A. alpha      B. beta      C. L configuration      D. D configuration

7. ___The rate limiting step of purine nucleotide de novo synthesis is made irreversible by:

A. displacement of NH₂ group            C. hydrolysis of ATP

B. liberation of glutamate                    D. hydrolysis of PPi

8. ___The reaction catalyzed by GAR synthetase in the presence of glycine is unique because:

A. the only step in de novo synthesis wherein more than one atom is acquired

B. it is a flux generating step

C. irreversible

D. ATP hydrolysis drives the reaction to completion

9. ___In GAR synthetase reaction, these atoms are acquired in the presence of glycine:

A. C₆, C₂ & N₇      B. C₄, C₅ & N₇      C. C₂, C₈ & N₉      D. C_4, C₈ & N₃

10. ___The form of tetrahydrofolate from which C₂ of purine ring is derived by the cells:

A. N⁵ N¹⁰ methylene THF                  C. formimino THF

B. N¹⁰ formyl THF                              D. methyl THF

11. ___The fumarate portion of aspartate enters the Kreb’s cycle thru this intermediate:

A. fumarate      B. succinyl CoA      C. oxaloacetate      D. α keto glutarate

12. ___The first purine nucleotide generated in de novo synthesis:

A. AMP           B. GMP           C. XMP           D. IMP

13. ___The energy utilized by adenylosuccinate synthetase enzyme to synthesize AMP from IMP:

 A. ATP           B. CTP            C. GTP            D. UTP

14.  ___Lesh-Nyhan syndrome is caused by a deficiency of this enzyme:

A. hypoxanthine-guanine phosphoribolsyl transferase

B. adenine phosphoribosyl transferase

C. thymidine kinase

D. uridine-cytidine kinase

15. ___In eukaryotes the rate limiting step for pyrimidine nucleotide de novo pathway is catalyzed by:

A. carbamoyl PO₄ synthetase I            C. aspartate transcarbamoylase

B. carbamoyl PO₄ synthetase II        D. dihydroorotase

16. ___The source of nitrogen for the rate limiting step of pyrimidine nucleotide de novo pathway:   A. ammonia      B. amide of D      C. amide of E      D. amino of E

17. ___Which atom of pyrimidine bases is also found in purine bases and shares the same origin, aspartate?      A. N₃             B. N₁             C. N₇              D. N₉

18. ___The first pyrimidine nucleotide generagted in its synthesis:

 A. OMP         B. UMP         C. CMP         D. TMP

19. ___The source of the electrons and protons for the synthesis of deoxynuycleotides:

A. thioredoxin (oxidized)                   C. NADPH + H

B. thioredoxin (reduced)                   D. NADH + H

20. ___The mitochondrial enzyme of pyrimidine nucleotide de novo synthesis:

A. dihydrooratoase                                      C. orotate phosphoribosyl transferase

B. dihydroorotate dehydrogenase           D. aspartate transcarbamoylase

21. ___The final product of purine nucleotide degradation:

A. urea        B. ammonia        C. orotic acid        D. uric acid

22.  ___β amino isobutyrate will enter the Kreb’s cycle thru this intermediate:

A. α ketoglutarate       B. fumarate       C. succinyl CoA       D. malate

23.  ___A drug used to treat urinary tract infections & inhibits dihydrofolate reductase:

A. methotrexate       B. aminopterin       C. trimethoprim       D. allopurinol

24. ___Uric acid is the degradation product of:

A. cytosine        B. adenine        C. thymine        D. uracil

25. ___A chemotherapeutic agent that inhibits steps in purine nucleotide de novo pathway that utilizes glutamine as source of nitrogen:

A. azaserine      B. aminopterin      C. azidothymidine      D. hydroxyurea

 :

A. urea        B. ammonia        C. orotic acid        D. uric acid

22.  ___β amino isobutyrate will enter the Kreb’s cycle thru this intermediate:

A. α ketoglutarate       B. fumarate       C. succinyl CoA       D. malate

23.  ___A drug used to treat urinary tract infections & inhibits dihydrofolate reductase:

A. methotrexate       B. aminopterin       C. trimethoprim       D. allopurinol

24. ___Uric acid is the degradation product of:

A. cytosine        B. adenine        C. thymine        D. uracil

25. ___A chemotherapeutic agent that inhibits steps in purine nucleotide de novo pathway that utilizes glutamine as source of nitrogen:

A. azaserine      B. aminopterin      C. azidothymidine      D. hydroxyurea


How often will cells divide under ideal growing conditions?
a. Every 20 minutes
b. every 45 minutes
c. every 2 hours
d. every 12 hours 
A

How do DNA molecules vary from one species to another?
a. the type of nitrogenous bases they contain
b. number of genes and non-coding regions
c. the way nitrogenous bases pair
d. the directionality of the strands 
B

All of the following regulate gene expression in eukaryotes except:
a. enhancers
b. transcription factors
c. Histone-DNA complexes
d. Operators 
D

What is a possible outcome of site-specific mutagenesis?
a. additions or deletions to DNA 
b. improved protein function
c. cell death
d. all of the above 
D


What enabled the onset of recombinant DNA technology?
a. the ability to identify similarities and differences between individuals
b. the Biotechnology Industry Organization
c. The ability to cut and paste pieces of DNA together 
d. the beginning of research findings getting published in scientific journals
C


Which of the following is an example of a product easily found in nature?
a. antibiotic
b. GMO 
c. recombinant DNA 
d. all of the above
A

Recombinant DNA is the term used for
a. DNA that has been cut with restriction enzymes
b. DNA molecules composed of DNA from different sources
c. Molecules that have undergone DNA fingerprinting analysis
d. GEnetic information from selectively bred organisms
B


One type of ribonucleic acid coded for by the "junk DNA" is
a. mRNA
b. siRNA 
c. tRNA 
d. rRNA
e. none of these
B

The type of ribonucleic acid that is translated into proteins is
a. mRNA
b. siRNA 
c. tRNA 
d. rRNA
e. none of these
A

Which of the following structures are found in prokaryotic cells? 
a. nucleus
b. mitochondria
c. plasma membrane 
d. none of these
C

The order of amino acids on a polypeptide chain is encoded by
a. DNA 
b. mRNA
c. rRNA
d. regulatory proteins
B

Nucleotides are connected together in a DNA molecule by
a. hydrogen bonds
b. antiparallel bonds
c. peptide bonds
d. phosphodiester bonds
D

How is gene expression controlled in prokaryotic cells?
a. Operons
b. Ribosomes 
c. Enhancers
d. All of the above
A

All of the following may be used to induce changes at a particular locus on a DNA molecule except:
a. Exposure to chemicals
b. Exposure to radiation
c. Exposure to low temperatures
d. Viral infection
C

How many hydrogen bonds hold base pairs together
a. two hydrogen bonds for each pair
b. three hydrogen bonds for each pair
c. two hydrogen bond between A and T, and three for G and C 
d. three hydrogen bond between A and T, and two for G and C
C



All of the following are reasons some people need recombinant protein therapeutics except:
a. They need stronger nails and hair
b. their body doesn't synthesize that protein at the right time
c. the protein their body synthesizes is defective
d. their body doesn't synthesize enough of that protein 
A

Prokaryotic DNA is contained in 
a. the cytoplasm
b. the nucleus
c. membrane-bound organelles
d. multiple chromosomes 
A


A typical E. coli genome contains about ____ genes.
a. 2
b. 5-10
c. 2000
d. 4000 
C

In eukaryotic cells, after an mRNA has been transcribed
a. the operon turns off
b. it immediately gets translated into a polypeptide
c. exons are removed
d. introns are removed 
D

All of the following are reasons to use TRIS during an electrophoresis except 
a. to stabilize the pH
b. to conduct electricity
c. to maintain the shape of molecules
d. to stain molecules 
D

R plasmids are useful for both bacteria and scientists because they contain 
a. ribosomal RNA genes
b. one or more antibiotic resistance genes
c. recombinant DNA products
d. all of the above 
B

A linear piece of DNA was cut with a restriction enzyme and four bands were visualized after electrophoresis. How many cuts were made? 
a. 1
b. 2
c. 3
d. 4 
C

Eukaryotic gene expression can be increased by
a. operators
b. introns
c. enhancer molecules
d. all of the above 
C

When a regulatory molecule binds to an operator,
a. gene expression is turned on
b. gene expression is turned off
c. RNA polymerase may bind to the promoter region
d. enhancer molecules fall off 
B

MOst of the DNA in humans is 
a. coding sequence
b. spacer DNA within and between genes
c. for regulatory processing

d. for transcription factor gene regulation 
B

How is the packaging of DNA different in eukaryotes and prokaryotes?
a. eukaryotes have more chromosomes and each is linear
b. eukaryotes have more chromosomes and each is circular
c. eukaryotes have some carbohydrate molecules attached to their chromosomes
d. eukaryotes have less chromosomes than prokaryotes 
A

Genes code for
a. Enzymes
b. polypeptides
c. RNA 
d. all of these
e. none of these 
D


Semi-conservative replication means: 
a. the old DNA is completely broken down
b. only half of the DNA is replicated
c. each new DNA molecule has half of the old one
d. the old DNA remains completely intact. 
C

A replication fork is
a. an area where DNA separates into two strands and new DNA synthesis occurs 
b. a molecule utensil required to stab nucleotides for DNA synthesis 
c. A point where cell must decide whether to replicate DNA
d. A "factory" made of many enzymes to bind DNA for replication 
A

The antiparallel nature of double stranded DNA means
a. the two strand run from 5' to 3' in opposite directions
b. the 5' end of the two strands are on opposite ends of the molecule
c. the two DNA strands twist around each other in a helical pattern
d. both a and b are correct
e. both a and c are correct 
D


The sequence of nitrogenous bases on one strand of DNA may determine the sequence of 
a. fatty acids in a fat molecule
b. amino acids in a protein molecule
c. sugars in a polysaccharide molecule
d. bases in a protein molecule 
B

What genetic modification was made to roundup ready soybeans?
a. they contain the gene Roundup to produce toxins that poison insects
b. They contain a gene that makes soybeans resistant to herbicide Roundup
c. They contain a gene to produce a growth hormone gene that decrease the time until the soybeans mature 
d. They contain a gene for frost tolerance so that soybeans may be grown year round in cold climates 
B


Prolonged use of a particular antibiotic might result in
a. bacterial sensitivity or intolerance to the molecule 
b. antimicrobial properties exhibited by the bacterium
c. bacterial resistance to the molecule
d. increased antibiotic specificity 
C
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How are Chinese Hamster Ovary cells used in process development of a biotechnology product?
a. they are used during clinical trials to help determine the efficacy of the pharmaceutical
b. they are used during clinical trials to help determine the proper dosage of the pharmaceutical
c. they are part of the protein purification step 
d. They are transfected with recombinant DNA to produce large quantities of a specific protein 
D
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What extra effort might be taken to extract DNA or protein from a plant cell?
a. Addition of vitamin solution to increase cell activity
b. Treating it with an enzyme to break down cellulose in the cell walls
c. mixing sample with iron sulfate to increase molarity
d. Incubation of sample at 4 degree C with glass beads 
B
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Herbal therapies have been used in some cultures for hundreds of years, however cautions must be taken when using herbal remedies for all of the following reasons except
a. Herbal products are not subject to FDA approval
b. Adverse effects may occur if the wrong concentration is taken 
c. Herbal remedies often taste better than other medicines 
d. Certain combinations of herbal therapies may be harmful 
C
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New antibiotics are in big demand because
a. new methods need to be devised for large scale production
b. the flu virus infects many people each year.
c. bacteria mutate quickly and become resistant to the antibiotics
d. all of the above 
C


Recombinant DNA
a. is used to produce hundreds of other DNA products
b. can be found in fungus cells
c. is produced by pasting DNA together from two sources
d. is larger than a typical chromosome 
C
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What is amylase? 
a. an enzyme
b. a sugar 
c. a polysaccharide
d. a starch 
A

A piece of DNA that results from being spliced into a vector is called
a. a sticky end
b. recombinant DNA
c. an endonuclease
d. an RFLP 
B
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Why are plasmid preparations done?
a. to verify that transformants received the rDNA and to store plasmids for future transformations
b. to collect mini, midi or mega quantities of protein product and perform assays to check for enzyme activity
c. to perform an ethidium bromide dot blot test for DNA

d. to verify protein purity in transformed cells 
A


After doing plasmid prep the presence of DNA can be confirmed by
a. doing an sodium chloride dot test
b. cutting the plasmid with restriction enzymes and confirming the fragment sizes.
c. checking the concentration with a pH meter.
d. Biuret testing 
B

What does it mean to probe DNA
a. performing an ethanol precipitation and then spooling the DNA with a glass rod 
b. locating a gene of interest using a short complementary piece of DNA 
c. treat with restriction enzymes and ligate the sticky ends 
d. spin the DNA in a centrifuge and collect the supernatant 
B
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Cutting DNA into fragments and then figuring out their order is called
a. restriction fragment length polymorphism (RFLP)
b. restriction enzyme mapping
c. restriction digest 
d. rDNA probing 
B

What treatment encourages cells to incorporate rDNA plasmids during a bacterial transformation? 
a. Heat shock in warm water bath followed by ice bath
b. Plating on nutrient agar with antibiotic
c. Achieving exponential cell growth
d. Assaying for recombinant proteins 
A
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Example of DNA vector is a(n)
a. ribosome
b. fungus
c. algae
d. plasmid 
D
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After the gene for protein of interest has been identified, there are several methods for locating it. Which of the following is not one of those methods?
a. Fluorescent DNA probes can be used to hybridize to the DNA sequence of interest and be detected 
b. Protein assays can be performed
c. DNA fragments can be electrophoresed through a gel and the DNA fragment of interest can be detected by Southern blotting 
d. PCR products can be generated with the use of primers and a thermal cycler 
B

After cell lysis the cell contents are removed from solutions, leaving DNA, by using all the reagents listed except:
a. RNA
b. Solvents
c. Centrifugation
d. Enzymes 
A

Which of the following will work to extract and isolate chromosomal DNA from bacterial cells?
a. Add lysozyme to cells in buffered solution, treat with detergent and enzymes to remove proteins, centrifuge and then collect DNA in the supernatant 
b. Add enzyme cocktail containing lysozyme, RNase, and proteases to burst cells, then salts and detergent to remove proteins, followed by centrifugation, where supernatant is dumped and the pellet is resuspended in buffer to collect DNA
c. Add NaOH and SDS to burst cells, precipitate out proteins, and isolate DNA through a series of ethanol and isopropanol precipitations
d. Centrifuge cell mixture to burst cells, collect supernatant, precipitate out proteins with TE buffer, centrifuge again and add lysozyme 
A

A new _____ is an example of a product that could have been derived from genetic engineering
a. Pharmaceutical
b. Vitamin 
c. Metal
D. Centrifuge 
A
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Form of selection used to identify transformed cells?
a. the green fluorescent protein gene is included on the vector plasmid
b. suspected transformed cells are spun in a centrifuge
c. an antibiotic resistance gene is added to the vector
d. the target gene is recombined into a plasmid with the beta-galactosidase gene C
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Purpose of adding cations, (Ca+2 or Mg+2) to host cells before transformation? 
a. increase transformation efficiency
b. allows for selection of transformed cells
c. gets rid of sticky ends
d. all of the above 
A
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How is DNA spliced?
a. PCR
b. Scalpel
c. Restriction enzymes
d. Probes 
C

In a mini-prep, how is DNA extracted in the final step?
a. alcohol precipitation
b. potassium acetate precipitation
c. TE buffer precipitation
d. treatment with SDS-NaOH 
A