Complete Test Bank Ch20 Introduction to Molecular Genetics

General, Organic, and Biochemistry, 10e (Denniston)

Chapter 20 Introduction to Molecular Genetics

1) What important discovery about DNA was made by Irwin Chargaff?

A) The structure of DNA was a double-stranded helix.

B) Chromosomes were DNA-containing structures within the cell.

C) The genetic code consisted of a sequence of 3 bases.

D) DNA replication is a semiconservative process.

E) The amounts of adenine and thymine in all DNA were equal, as were the amounts of guanine and cytosine.

2) Who first described the three-dimensional structure of DNA in 1953?

A) Watson and Crick

B) Chargaff

C) Garrow

D) Mendeleev

E) Einstein

3) Which nitrogenous base is normally found in RNA, but not in DNA?

A) pyridine

B) urea

C) thymine

D) uracil

E) purine

4) Which of the following statements concerning nucleic acids is FALSE?

A) Nucleic acids are polymers of repeating monomer units called nucleotides.

B) DNA is responsible for the storage of genetic information.

C) RNA is responsible for the transfer and expression of genetic information.

D) A gene is a sequence of bases on a DNA strand that codes for a particular protein.

E) A chromosome is a complex of 46 DNA molecules intertwined with proteins.

5) What is the name for the nucleotide formed from deoxyribose, adenine, and two phosphoryl groups?

A) adenosine phosphate

B) deoxyadenosine phosphate

C) D-adenine diphosphate

D) deoxyriboadenine diphosphate

E) deoxyadenosine diphosphate

6) One strand of the DNA molecule advances in the 3' → 5' direction. In what direction does its complementary strand advance?

A) 3' → 5'

B) N-terminal to C-terminal

C) 5' → 3'

D) O-terminal to P-terminal

E) There is no set direction for the complementary strand; it depends on the organism.

7) Nucleic acids are polymers of nucleotides.  Which of the following correctly represents a nucleotide that may be found in nucleic acids?

A) I

B) II

C) III

D) I, II, and III

E) I and IV

8) What term is used to describe the point at which new deoxyribonucleotides are added to the growing daughter strand during DNA replication?

A) replication junction

B) transcription point

C) replication fork

D) parental/daughter boundary

E) addition point

9) What is the function of the enzyme DNA polymerase in replication?

A) It unwinds the double helix of DNA and separates the two strands.

B) It reads the sequence of nucleotides on the parental strand of DNA and catalyzes the polymerization of a complementary daughter DNA strand.

C) It reads the codons on a DNA molecule and catalyzes the polymerization of a complementary mRNA strand.

D) It connects the short Okazaki fragments formed in the lagging strand.

E) It carries the amino acids that are necessary to form a new daughter strand.

10) The mechanism of DNA replication is said to be semi-conservative. Which of the following best describes what this term indicates with respect to DNA replication?

A) The daughter DNA strands are formed by complementary, not identical, base pairing.

B) The daughter DNA strands are formed by both complementary as well as identical base pairing.

C) The daughter DNA strands produced in DNA replication each contain one strand of the original parent DNA and one newly synthesized strand.

D) Nucleoside triphosphates as well as nucleoside monophosphates are used to provide the complementary bases.

E) DNA replication proceeds in both the 3'→5' direction as well as the 5'→3' direction.

11) What directional flow of information is referred to as the "central dogma of molecular biology"?

A) DNA → RNA → protein

B) RNA → DNA → protein

C) protein → DNA → RNA

D) protein → RNA → DNA

E) RNA → protein → DNA

12) Which statement concerning DNA is FALSE?

A) DNA stands for diribonucleic acid.

B) DNA molecules are located in the nucleus of the cell.

C) DNA molecules exist tightly wrapped around proteins called histones.

D) The genetic information of an organism is stored in DNA.

E) The four common bases found in DNA are adenine, cytosine, guanine, and thymine.

13) What sequence on a DNA molecule indicates where RNA polymerase should begin transcription?

A) replication fork

B) Okazaki fragment

C) promoter

D) replication origin

E) anticodon loop

14) DNA isolated from human cheek cells was found to contain 21% guanine. What else is true about the base composition of this DNA sample?

A) It contains 79% cytosine.

B) It contains 79% adenine and thymine.

C) It contains 21% adenine, 21% cytosine, and 21% thymine.

D) It contains 21% cytosine, 29% adenine, and 29% thymine.

E) It is impossible to say anything specific about the percentages of adenine, cytosine, and thymine without further analysis.

15) RNA splicing involves the removal of nucleotide sequences that do not code for a protein in a newly formed mRNA. What are these nonprotein coding sequences called?

A) caps

B) introns

C) exons

D) operons

E) genes

16) The mRNA codon CAU specifies the amino acid histidine (His). What sequence of nucleotides is found in the anticodon loop of the tRNA molecule that carries His to the ribosomes?

A) CAU

B) CAT

C) GTA

D) GUA

E) GUT

17) The genetic code is composed of triplets using four different bases. How many different codons (triplets) are there?

A) 12

B) 24

C) 36

D) 64

E) 128

18) The genetic code is said to be "degenerate". What does this term indicate about the genetic code?

A) Different triplet codons serve as code words for the same amino acid.

B) The genetic code contains regions of nonprotein coding sequences.

C) The genetic code can easily undergo mutations that can lead to illnesses such as cancer.

D) The genetic code is repetitive, and is identical in all species.

E) The genetic code must be rewritten several times before a functional protein is formed.

19) Hydrogen bonding plays an important role in all but one of the items below. Which one does NOT involve hydrogen bonding?

A) DNA replication

B) DNA double helix

C) DNA primary structure

D) synthesis of mRNA from DNA

E) codon/anticodon recognition

20) Which two amino acids are encoded by only a single codon each?

A) proline and glycine

B) cysteine and arginine

C) phenylalanine and isoleucine

D) tyrosine and proline

E) methionine and tryptophan

21) Where does protein synthesis occur inside the cell?

A) in the cell membrane

B) at the ribosomes

C) inside the mitochondria

D) at the lysosomes

E) in the nucleus

22) What molecule carries the anticodon sequence that is complementary to the codon sequence on messenger RNA?

A) operons

B) restriction enzymes

C) transfer RNA

D) DNA polymerase

E) ribosomal RNA

23) What type of mutation results in the loss of one or more nucleotides from a DNA sequence?

A) omission

B) deletion

C) point

D) silent

E) fragmental

24) What type of mutation involves the substitution of a single base for another in a codon?

A) switch

B) insertion

C) point

D) silent

E) fragmental

25) What is the term used to describe a mutation that does not alter the amino acid sequence of the protein encoded by a gene?

A) nonsense

B) sensible

C) point

D) silent

E) fragmental

26) What commonly results when DNA is damaged by ultraviolet light?

A) cysteine dimers

B) pyrimidine dimers

C) the conversion of purine bases to pyrimidine bases

D) the conversion of pyrimidine bases to purine bases

E) an increased production of DNA

27) What term is used to describe bacterial enzymes that are used to "cut" the sugar-phosphate backbone of DNA molecules at specific nucleotide sequences?

A) DNA polymerases

B) DNA phosphatases

C) restriction enzymes

D) retroviral enzymes

E) reverse transcriptases

28) What is accomplished by the use of gel electrophoresis in DNA analysis?

A) separation of DNA fragments according to size

B) hybridization of DNA fragments

C) formation of daughter DNA molecules

D) identification of base composition

E) rapid DNA synthesis

29) What is the requirement for a radiolabeled DNA or RNA molecule (i.e., a probe) to hybridize to a section of DNA?

A) Both strands must contain a primer.

B) A cloning vector must be present.

C) The strands must have the same bacterial origin.

D) The strands must have complementary sequences.

E) The strands must have identical sequences.

30) Which technique allows scientists to produce unlimited amounts of any gene of interest?

A) gel electrophoresis

B) polymerase chain reaction

C) southern blot hybridization

D) thermo coupling

E) the Ames test

31) What enzyme functions to catalyze the formation of phosphodiester bonds between two fragments of DNA?

A) Thermus aquaticus

B) DNA phosphatase

C) DNA ligase

D) Restriction enzymes

E) Taq polymerase

32) DNA and RNA are polymers of nucleotides. The nucleotides in each of these molecules are joined together by which of the following?

A) complementary base pairing

B) hydrogen bonding

C) β-N-glycosidic linkages

D) 3'-5' phosphodiester bonds

E) peptide bonds

33) Which of the following is NOT a product of recombinant DNA technology that is used in medicine?

A) insulin

B) aspirin

C) human growth hormone

D) influenza vaccine

E) hepatitis B vaccine

34) What is the key function of a DNA primer in the polymerase chain reaction (PCR)?

A) It hybridizes to the beginning of a gene, creating a site for DNA polymerase to initiate DNA synthesis of the selected gene.

B) It aids in winding the newly produced DNA molecule with proteins to form a chromosome.

C) It catalyzes the separation of the two strands of DNA being copied.

D) It is the source of the four nucleotides needed in PCR.

E) It acts as a buffer to main a constant pH in the PCR solution.

35) What key role does the bacterium Thermus aquaticus play in the polymerase chain reaction (PCR)?

A) It is the source of the four nucleotides needed in PCR.

B) It serves as the platform on which PCR proceeds.

C) It provides the heat-stable DNA polymerase used in PCR.

D) It aids in winding the newly produced DNA molecule with proteins to form a chromosome.

E) It acts as a buffer to maintain a constant pH in the PCR solution.

36) Approximately how many base pairs make up the human genome?

A) 3 million

B) 64 million

C) 3 billion

D) 10 billion

E) It is still unknown.

37) DNA is a double-stranded nucleic acid that exists as a double helix. Which of the following is responsible for holding the double helix of DNA together?

A) Phosphodiester bonds between the two strands.

B) N-glycosidic linkages between the sugar-phosphate backbone on each strand.

C) Hydrogen bonding between complementary base pairs on the two strands.

D) Disulfide bonds between the nucleotides on the two strands.

E) Thymine dimers between the two strands.

38) Which of the following is NOT a base common to both DNA and RNA?

A) adenine

B) thymine

C) guanine

D) cytosine

E) All of the choices are bases common to both DNA and RNA.

39) Which structure correctly represents the dinucleotide sequence GC that is found in DNA?

A)

B)

C)

D)

40) Which pyrimidine bases are found in DNA?

A) adenine and thymine

B) thymine and guanine

C) adenine and guanine

D) cytosine and thymine

E) cytosine and adenine

41) Which of the following represents the backbone structure of a DNA polymer?

A) base-sugar (ribose)

B) phosphate-sugar (deoxyribose)

C) base-sugar (deoxyribose)

D) phosphate-base

E) phosphate-sugar (ribose)

42) Base pairing between guanine and cytosine is more stable than base pairing between adenine and thymine. Which of the following best explains why?

A) G/C base pairing involves two large purine bases, while A/T base pairing involves two smaller pyrimidine bases.

B) G/C base pairing involves three hydrogen bonds, while A/T base pairing involves only two hydrogen bonds.

C) G/C base pairs are smaller and more compact than A/T base pairs.

D) G/C base pairs are more widely separated and not as crowded as A/T base pairs.

E) G/C base pairs appear in DNA and RNA, while A/T base pairs appear only in DNA.

43) What is the term used to describe the relationship between the nucleotide sequences on the two strands of DNA?

A) They are enantiomers.

B) They are cooperative.

C) They are complementary.

D) They are mirror images.

E) They are identical.

44) What enzyme is responsible for reading a parental strand of DNA and catalyzing the polymerization of a complementary daughter strand?

A) peptide polymers

B) DNA isomerase III

C) DNA polymerase

D) transferase coenzyme A

E) None of the choices are correct.

45) Which type of RNA carries the needed amino acids to the ribosomes for use in protein synthesis?

A) transfer RNA

B) messenger RNA

C) ribosomal RNA

D) RNA polymerase

E) None of the choices are correct.

46) Which enzyme catalyzes the transcription of DNA?

A) transfer RNA

B) messenger RNA

C) DNA ligase

D) RNA polymerase

E) DNA polymerase

47) Which term represents the process in which the genetic information stored in DNA is read and copied into an mRNA molecule?

A) replication

B) translation

C) transcription

D) cloning

E) mutation

48) Which of the following correctly describes a triplet codon?

A) An RNA molecule that contains three ribonucleotides.

B) A sequence of three amino acids in a protein that signals for transcription.

C) A sequence of three nucleotides on mRNA that codes for a specific amino acid.

D) A sequence of three reactions that leads to protein synthesis.

E) A DNA molecule that contains three genes that each code for a different protein.

49) Which of the following correctly describes a chromosome?

A) The location inside the cell where protein synthesis occurs.

B) A segment of a DNA molecule that codes for a specific protein.

C) A complex of 46 DNA molecules wrapped tightly together in a bundle.

D) A sequence of three nucleotides that code for a specific amino acid.

E) A complex of proteins and a single DNA molecule wrapped tightly together in a bundle.

50) Phosphate groups can be esterified at any hydroxyl group on a pentose nucleotide. What position is the most common?

A) 1'

B) 2'

C) 3'

D) 4'

E) 5'

51) Which of the following components is bonded to the backbone chain of DNA by N-glycosidic bonds?

A) phosphoryl groups

B) nucleotides

C) pentoses

D) nitrogenous bases

E) ammonia

52) Adenine present in one strand of a DNA molecule is always hydrogen bonded to what base in the other strand?

A) thymine

B) guanine

C) cytosine

D) uracil

E) adenine

53) How many turns of the DNA double helix correspond to twenty base pairs?

A) one

B) six

C) ten

D) two

E) twenty

54) Which of the following best describes the primary function of mRNA in a cell?

A) to serve as an enzyme in the formation of the DNA double helix

B) to serve as an enzyme in DNA replication

C) to transport amino acids to the ribosomes for protein synthesis

D) to transcribe the instructions for protein synthesis from DNA and carry this information to the ribosomes

E) to serve as the structural site for protein synthesis

55) Meselson and Stahl (1958) reported experimental results involving nitrogen-labeling relevant to which of the following?

A) the helical structure of DNA

B) the role of RNA in DNA transcription

C) the basis for DNA fingerprinting

D) the mechanism of the polymerase chain reaction

E) the semiconservative mechanism of DNA replication

56) Which term describes the process by which a single strand of DNA serves as a template for the synthesis of an RNA molecule?

A) translation

B) transcription

C) initiation

D) elongation

E) replication

57) Which term describes the process by which a message from DNA in the form of mRNA is converted into the primary sequence of amino acids in a protein?

A) translation

B) transcription

C) initiation

D) elongation

E) translocation

58) Which of the following molecules carries the genetic information for a protein from DNA to the ribosome?

A) mRNA

B) tRNA

C) amino acids

D) coenzyme A

E) ATP

59) Which of the following is a structural and functional component of the ribosome?

A) mRNA

B) tRNA

C) rRNA

D) DNA

E) ATP

60) Which term refers to the sequence of three nucleotides at the base of the cloverleaf of a tRNA molecule?

A) codon

B) promoter

C) P-site

D) anticodon

E) A-site

61) What is the term used to describe complexes of many ribosomes all simultaneously translating a single mRNA?

A) carcinogens

B) promoters

C) polysomes

D) codons

E) mutagens

62) A DNA strand has the partial sequence 5'-GACTGA-3'. What would be the sequence of its complementary strand?

A) 5'-AGUCAG-3'

B) 3'-AGTCAG-5'

C) 5'-CTGACT-3'

D) 3'-CTGACT-5'

E) 5'-CUGACU-3'

63) Which of the statements concerning the nucleotide with the name adenosine-5'-monophosphate (AMP) is FALSE?

A) It is a ribonucleotide.

B) It is composed of ribose, adenine, and a single phosphate group.

C) It is found in RNA only.

D) The phosphate group is attached to the 5' carbon of adenine.

E) All of the statements are true.

64) Which of the following changes in a DNA molecule may have no effect on the protein for which the DNA codes?

A) a deletion mutation

B) formation of a thymine dimer

C) changing the first base in a triplet

D) changing the second base in a triplet

E) changing the third base in a triplet

65) A gene contains the sequence 3'-GACTGA-5' on its template strand. What would be the sequence of the transcribed mRNA molecule?

A) 3'-GACUGA-5'

B) 5'-GACUGA-3'

C) 5'-CTGACT-3'

D) 5'-CUGACU-3'

E) 3'-AGTCAG-5'

66) How are the correct amino acids brought to the ribosomes for protein synthesis?

A) The amino acids are synthesized directly at the ribosomes by the hydrolysis of dietary protein.

B) Acetyl-CoA carries the amino acids that match the codon on DNA.

C) Amino transport proteins called lipoproteins bring the correct amino acids to the ribosomes.

D) Transfer RNA molecules, whose anticodon loop contains the complementary sequence of an mRNA codon, carry the amino acids.

E) Amino acids are carried in the interior of the DNA double helix, then carried to the ribosomes.

67) Which of the following correctly describes what occurs in the biological process of translation?

A) The two strands of the DNA double helix separate, and two new complementary strands are formed.

B) The genetic code of DNA is rewritten in mRNA, which leaves the nucleus and carries the information to the ribosomes.

C) The genetic code contained in mRNA is interpreted by tRNA, and the specific amino acids are brought to the ribosomes for protein synthesis.

D) Complementary base pairing between mRNA and the template strand of DNA occurs.

E) A new mRNA molecule is synthesized from the information contained in DNA.

68) Which of the following is NOT a component of a nucleotide?

A) nitrogenous base

B) five-carbon sugar

C) phosphoryl group

D) amino acid

E) A nucleotide consists of all of these components.

69) Which statement properly describes the difference between ribose and deoxyribose?

A) Ribose is an L-sugar and deoxyribose is a D-sugar.

B) Deoxyribose has one less oxygen atom than ribose.

C) Ribose has an α-arrangement and deoxyribose has a β-arrangement.

D) Ribose is a five-carbon sugar and deoxyribose is a six-carbon sugar.

E) Deoxyribose has two more hydroxyl groups than ribose.

70) A DNA template strand having the sequence shown below would produce an mRNA molecule with what sequence?

3'-CGATCA-5'

A) 3'-CGATCA-5'

B) 3'-CGAUCA-5'

C) 5'-CGAUCA-3'

D) 5'-GCUAGU-3'

E) 5'-GCTAGT-3'

71) What type of bond connects the phosphate group to the sugar in a nucleotide?

A) phosphoester bond

B) phosphoether bond

C) glycosidic bond

D) hydrogen bond

E) ionic bond

72) Which statement concerning the double helix structure of DNA is FALSE?

A) The helix completes one turn every 10 base pairs.

B) Base pairs in the double helix are attached by way of hydrogen bonding.

C) The two strands of the double helix are called parallel strands.

D) The base pairs are directed in toward the middle of the double helix.

E) In the double helix, adenine connects to thymine and cytosine connects to guanine.

73) Which of the following are correct base pairs in DNA?

1. adenine and thymine

2. adenine and cytosine

3. thymine and guanine

4. cytosine and guanine

A) 1 and 4

B) 2 and 3

C) 1, 2, and 3

D) 1, 3, and 4

E) All of the choices are correct.

74) Which statement is FALSE concerning the RNA structure?

A) RNA is usually single-stranded.

B) RNA contains ribose instead of deoxyribose.

C) RNA has a phosphoester linkage connecting the sugar to the phosphate group.

D) Thymine is not in RNA.

E) RNA and DNA are approximately the same size.

75) Which term is used to describe the process in which a double stranded DNA molecule unwinds, separates, and each strand serves as a template in the synthesis of its complement?

A) cloning

B) replication

C) duplication

D) transcription

E) mutation

76) The two strands of the DNA molecule are antiparallel to one another.

77) E. coli contains a single circular piece of DNA as its genetic material.

78) Transfer RNA (tRNA) is a complementary copy of a gene on DNA.

79) All tRNA molecules have a CCA sequence at their 3' ends.

80) Point mutations always result in a change in the amino acid sequence of the protein encoded by the gene.

81) The peptidyl tRNA binding site holds a tRNA molecule bonded to the growing peptide chain.

82) In eukaryotes, the initiator tRNA is bonded to methionine.

83) In protein synthesis, new amino acids are attached to the N-terminus of the growing peptide chain.

84) Xeroderma pigmentosum is a genetic disease of DNA repair that results in a high incidence of skin cancer.

85) The only important requirement for hybridization of DNA fragments is the presence of complementary nucleic acid sequences.

86) RNA can hybridize both to DNA and to other RNA molecules.

87) A DNA fingerprint requires 25-60 DNA strands that are unique to an individual.