Deck 9: DNA and Its Role in Heredity

Question 1

The rules formulated by Erwin Chargaff state that

A) A = T and G = C in any molecule of DNA.
B) A = C and G = T in any molecule of DNA.
C) A = G and C = T in any molecule of DNA.
D) A = U and G = C in any molecule of RNA.
E) DNA and RNA are made up of the same four nitrogenous bases.

Answer 1

A

Question 2

The DNA isolated from a newly discovered virus is found to be 32 percent A,18 percent C,18 percent G,and 32 percent T.The base composition of the complementary DNA would be _______ percent A,_______ percent C,_______ percent G,and _______ percent T.

A) 32;17;32;19
B) 19;32;17;32
C) 17;32;32;19
D) 25;25;25;25
E) 32;18;18;32

Answer 2

E

Question 3

A deoxyribonucleoside is a

A) deoxyribose plus a nitrogenous base.
B) sugar and a phosphate.
C) deoxyribose plus a nitrogenous base and a phosphate.
D) ribose plus a nitrogenous base.
E) nitrogenous base bonded at the 5' end to a sugar-phosphate backbone.

Answer 3

deoxyribose plus a nitrogenous base.

Question 4

Which statement about base pairing is false?

A) Purines pair with purines,and pyrimidines pair with pyrimidines.
B) In DNA,T pairs with A.
C) Complementary base pairing plays a role in DNA replication.
D) In DNA,C pairs with G.
E) The base pairs are of equal length.

Question 5

The primary information source used by Watson and Crick to determine the structure of DNA was

A) electron micrographs of individual DNA molecules.
B) light micrographs of bacteriophage particles.
C) light micrographs of individual bacterial chromosomes.
D) nuclear magnetic resonance analysis of DNA.
E) X-ray crystallography of double-stranded DNA.

Question 6

Purines include

A) cytosine,uracil,and thymine.
B) adenine and cytosine.
C) adenine and thymine.
D) cytosine and thymine.
E) adenine and guanine.

Question 7

Double-stranded DNA looks like a ladder that has been twisted into a helix,or spiral.The side supports of the ladder are

A) individual nitrogenous bases.
B) alternating bases and sugars.
C) alternating bases and phosphate groups.
D) alternating sugars and phosphates.
E) alternating bases,sugars,and phosphates.

Question 8

In the 1920s,a dye was developed that binds to DNA and stains nuclei in direct proportion to the amount of DNA present in the cells.The resulting experiments

A) provided circumstantial evidence that DNA is the genetic material.
B) demonstrated that DNA is the genetic material.
C) demonstrated that all species have the same amount of nuclear DNA.
D) demonstrated that diploid and haploid cells cannot have differing amounts of DNA.
E) confirmed that DNA is an important component of mitochondria and chloroplasts.

Question 9

What physical characteristic of DNA is affected by the pairing of purines with pyrimidines?

A) Its length
B) Its width
C) Its parallel nature
D) Its antiparallel nature
E) Its helix length

Question 10

The strands that make up DNA are antiparallel.This means that

A) one strand is positively charged,and the other is negatively charged.
B) the base pairings create unequal spacing between the two DNA strands.
C) the 5'-to-3'direction of one strand runs opposite to the 5'-to-3' direction of the other strand.
D) the twisting of the DNA molecule has shifted the two strands.
E) purines bond with purines and pyrimidines bond with pyrimidines.

Question 11

X-ray crystallography experiments carried out by _______ helped determine the structure of the DNA molecule.

A) Edwin Chargaff
B) Rosalind Franklin
C) James D.Watson
D) Francis Crick
E) Friedrich Miescher

Question 12

An alien DNA-like molecule is isolated from the frozen remains of a life form found beneath the Martian polar ice caps.In this sample,for every base designated Q,there is twice that amount of base R;for every base Z,there is twice that amount of base S.If the molecule contains 33.33 percent R,what percentage of Z would you expect to find?

A) 6 percent
B) 12 percent
C) 24 percent
D) 16.67 percent
E) 54.66 percent

Question 13

If a double-stranded DNA molecule contains 30 percent T,it must contain _______ percent G.

A) 20
B) 30
C) 40
D) 50
E) 60

Question 14

If a mutation changes a G to an A on one strand of a DNA molecule,with a corresponding change in its complement,which property will most likely be affected?

A) The width of the DNA molecule
B) The length of the DNA molecule
C) The nature of protein-DNA interactions
D) The number of purines in the double-stranded molecule
E) All of the above are equally likely.

Question 15

Early transformation experiments demonstrated that adding DNA from bacterium strain B to bacterium strain A could

A) produce bacterium strain C.
B) produce bacterium strain A.
C) produce bacterium strain B.
D) produce an equal mixture of strain A and strain B.
E) kill bacterium strain A.

Question 16

Which molecular model best describes the structure of the DNA molecule?

A) Single-stranded,with varying shapes
B) Straight and antiparallel
C) Triple-stranded,with varying shapes
D) Helical,double-stranded,and parallel
E) Helical,double-stranded,and antiparallel

Question 17

Which statement about infection of E.coli cells by bacteriophage T2 is true?

A) Proteins are the only phage components that enter the infected cell.
B) Both proteins and nucleic acids enter the cell.
C) Only protein from the infecting phage can be detected in progeny phage.
D) Nucleic acids,but not protein,enter the cell.
E) More than one phage particle is required to produce infection.

Question 18

Recall that two hydrogen bonds bind A and T,but three hydrogen bonds bind G and C.Because the stability of DNA is affected by the number of hydrogen bonds,with more bonds promoting more stability,which double-stranded DNA molecule would likely have the greatest stability?

A) A molecule with 20 percent A
B) A molecule with 26 percent G
C) A molecule with 32 percent C
D) A molecule with 38 percent T
E) More information is required to answer this question.

Question 19

Which molecule(s)function(s)to transfer information from one generation to the next in eukaryotes?

A) DNA
B) mRNA
C) tRNA
D) Proteins
E) Lipids

Question 20

Chargaff's rule states that

A) DNA must be replicated before a cell can divide.
B) viruses enter cells without their protein coat.
C) only protein from the infecting phage can also be detected in progeny phage.
D) only nucleic acids enter the cell during infection.
E) the amount of cytosine equals the amount of guanine.

Question 21

Suppose a new type of replicating molecule (TNA)is found.At the end of TNA replication,two TNA molecules are produced,each one consisting of a parental TNA strand and a new TNA strand.This is an example of

A) semiconservative replication.
B) conservative replication.
C) dispersive replication.
D) fission.
E) the transforming principle.

Question 22

A strand of DNA with the sequence 5'-ATTCCG-3'would have a complementary strand with the sequence

A) 5'-TAAGGC-3'.
B) 5'-ATTCCG-3'.
C) 5'-ACCTTA-3'.
D) 5'-CGGAAT-3'.
E) 5'-GCCTTA-3'.

Question 23

The energy necessary for making a DNA molecule comes directly from

A) sugar.
B) ATP.
C) the formation of phosphate ions.
D) NADPH.
E) NADH.

Question 24

The structure of DNA explains which three major properties of genes?

A) They contain genetic information,direct the synthesis of proteins,and are contained in the cell nucleus.
B) They contain nitrogenous bases,direct the synthesis of RNA,and are contained in the cell nucleus.
C) They replicate exactly,are contained in the cell nucleus,and direct the synthesis of cellular proteins.
D) They contain genetic information,can replicate exactly,and are susceptible to stable mutations.
E) They encode the organism's phenotype,are passed on from one generation to the next,and contain nitrogenous bases.

Question 25

Who first suggested a mode of replication for DNA?

A) Erwin Chargaff
B) Hershey and Chase
C) Rosalind Franklin
D) Watson and Crick
E) Gregor Mendel

Question 26

Which statement about the molecular architecture of the standard configuration of DNA is false?

A) The two strands run in opposite directions.
B) The molecule's twist is left-handed.
C) The molecule is a double-stranded helix.
D) It has a uniform diameter.
E) The helix has major and minor grooves.

Question 27

In DNA replication,each newly made strand is

A) identical in DNA sequence to the strand from which it was copied.
B) an incomplete copy of one of the parental strands.
C) oriented in the same 3'-to-5'direction as the strand from which it was copied.
D) complementary in sequence to the strand from which it was copied.
E) a hybrid molecule consisting of both ribo- and deoxyribonucleotides.

Question 28

Pyrophosphate is a

A) building block for DNA synthesis.
B) by-product of DNA synthesis.
C) precursor to DNA synthesis.
D) radioactive phosphate used in nucleic acid metabolism.
E) link between sugar molecules.

Question 29

During eukaryotic DNA replication

A) one template strand must be degraded to allow the other strand to be copied.
B) the template strands must separate so that both can be copied.
C) the template strands come back together after passing the replication fork.
D) origins of replication can give rise to multiple replication forks.
E) two replication forks diverge from each origin but one always lags behind the other.

Question 30

The characteristic of DNA that allows it to make an exact copy of itself is

A) its sugar-phosphate backbone.
B) its complementary base pairing.
C) the phosphodiester bonding of the helices.
D) the twisting of the molecule to form an $\alpha$ helix.
E) its antiparallel strands.

Question 31

The antiparallel relationship of the two strands of DNA refers to the

A) twisted configuration of the strands.
B) alternative branching pattern of the strands.
C) alignment of the strands,such that one strand starts with a 3' carbon and the other starts with a 5' carbon.
D) view at one end of the molecule-one strand has an A wherever the other has a T,and one has a G wherever the other has a C.
E) the different number of bonds between A and T versus G and C.

Question 32

Which statement about the semiconservative replication of DNA is true?

A) Each of the original strands acts as a template for a new strand.
B) Only one of the original strands acts as a template for a new strand.
C) It involves the complete separation of the original strands,the synthesis of new strands,and the reassembly of double-stranded molecules.
D) The intact double-stranded molecule is used as a template.
E) RNA is used as a template for DNA.

Question 33

What accounts for the uniform diameter of the DNA molecule?

A) The two sides of the molecule are held together by hydrogen bonds.
B) The alternating sugar and phosphate backbone coils around the outside of the helix.
C) One side of the molecule has an unconnected 5' phosphate group,and the opposite end has an unconnected 3'hydroxyl group.
D) The 3' carbon of one deoxyribose and the 5' carbon of another deoxyribose bond together.
E) A purine always bonds with a pyrimidine.

Question 34

In a growing DNA strand,each monomer is added to which carbon of the deoxyribose?

A) 1'
B) 2'
C) 3'
D) 4'
E) 5'

Question 35

Double-stranded DNA looks like a ladder that has been twisted into a helix,or spiral.The rungs of the ladder are

A) individual nitrogenous bases.
B) pairs of bases.
C) alternating bases and phosphate groups.
D) alternating sugars and bases.
E) alternating bases,sugars,and phosphates.

Question 36

DNA is held together in a double helix by the force of

A) the twist.
B) covalent bonds.
C) ionic bonds.
D) ionic interactions.
E) hydrogen bonds.

Question 37

Which element is not found in DNA?

A) Carbon
B) Oxygen
C) Nitrogen
D) Hydrogen
E) Sulfur

Question 38

Which feature of the Watson and Crick model of DNA structure explains its ability to function in replication and gene expression?

A) Each strand contains all the information present in the double helix.
B) There are structural and functional similarities between DNA and RNA.
C) The double helix is right-handed,not left-handed.
D) DNA replication does not require enzyme catalysts.
E) Bases are exposed in the major groove of the double helix.

Question 39

Although DNA is made up of only four different bases,it can encode the information necessary to specify the workings of an entire organism.It can do this because DNA

A) molecules are extremely long.
B) molecules are found in the nucleus.
C) is transcribed into RNA and then into proteins with specific functions.
D) is eventually translated into proteins,which are made up of 20 different amino acids.
E) uses the sugar deoxyribose.

Question 40

The nitrogenous bases (and the two strands of the DNA double helix)are held together by

A) weak van der Waals forces.
B) covalent bonds.
C) hydrogen bonds.
D) phosphate bonds.
E) All of the above

Question 41

Which event does not occur during DNA replication?

A) Unwinding of the parent double helix
B) Formation of short pieces that are connected by DNA ligase
C) Complementary base pairing
D) Use of a primer
E) Polymerization in the 3'-to-5' direction

Question 42

A research laboratory uses a cancer cell line that has undergone thousands of cell cycle divisions in the laboratory without any change in the length of its chromosomes.The cancer cell line is therefore likely to express

A) high levels of RNA polymerase.
B) very low levels of telomerase.
C) high levels of telomerase.
D) DNA polymerases with high fidelity.
E) high levels of ligase activity.

Question 43

Individual cells do not survive for the entire lifetime of an organism because

A) the enzyme telomerase is readily destroyed by the environment,resulting in cell death.
B) DNA replication is subject to errors that cause cell death.
C) Okazaki fragments disrupt protein synthesis,resulting in cell death.
D) the repeating telomeric sequence of TTAGGG interferes with normal DNA replication and leads to cell death.
E) the removal of the RNA primer following DNA replication leads to a shortening of the chromosome and eventual cell death.

Question 44

The primer used for DNA replication

A) is a short strand of RNA added to the 5'end of the template strand.
B) is needed only once on a leading strand.
C) remains on the DNA after replication.
D) ensures that there will be a free 5' end to which nucleotides can be added.
E) is added to only one of the two template strands.

Question 45

The stem cells in your intestinal walls divide frequently.Therefore,these cells are likely to

A) have high levels of telomerase.
B) have very low levels of telomerase.
C) undergo the polymerase chain reaction.
D) lack DNA polymerase.
E) lack Okazaki fragments.

Question 46

Which statement about a eukaryotic DNA replication primer is true?

A) It is a short strand of RNA added to the 3'end of the leading strand.
B) It is needed only once on a lagging strand.
C) It remains on the DNA after replication.
D) It ensures that there will be a free 5' end to which nucleotides can be added.
E) It is added to only one of the two template strands.

Question 47

In eukaryotes,the error rate of incorrect bases following proofreading and mismatch repair is approximately one in _______ per cell cycle.

A) 10
B) 10^-3
C) 10^-5
D) 10^-10
E) 10^-15

Question 48

What prevents the DNA repair system from "repairing" telomeres?

A) Telomerase is bound to telomeres,and thus blocks the repair system from binding to telomeres.
B) Telomerase catalyzes reactions that interfere with the repair system.
C) DNA polymerase blocks the repair system from accessing the telomere DNA.
D) Telomeres are at the end of the chromosome,and DNA is replicated in only one direction.
E) Protective proteins bind to telomeres,and therefore the repair system does not recognize telomeres as breaks.

Question 49

Which statement about Okazaki fragments is true?

A) They occur because DNA polymerase operates in only one direction along a strand of DNA.
B) They act as a primer that initiates DNA replication.
C) If they did not exist,the ends of chromosomes would get shorter with every replication.
D) It they did not exist,bases would pair with their complementary bases.
E) They reduce the mutation rate during DNA replication.

Question 50

The role of DNA ligase in DNA replication is to

A) add more nucleotides to the growing strand,one at a time.
B) open up the two DNA strands to expose template strands.
C) ligate base to sugar to phosphate in a nucleotide.
D) bond Okazaki fragments to one another.
E) remove incorrectly paired bases.

Question 51

What local effect would an RNA synthesis inhibitor have on DNA replication?

A) Primase would not be able to add bases to the DNA.
B) Primase would not be able to use DNA as a template.
C) Primase would be blocked from joining the holoenzyme complex.
D) Primase would not be able to provide primers for DNA polymerases.
E) There would be no effect on DNA replication.

Question 52

Why is RNA incorporated into the DNA molecule during DNA replication?

A) DNA polymerases can only add on to an existing strand.
B) RNA primase is able to use DNA as a template.
C) RNA primase must be incorporated into the holoenzyme complex.
D) DNA polymerase first synthesizes RNA.
E) RNA serves as the template for DNA synthesis.

Question 53

Fragments like those now called Okazaki fragments might have been hypothesized even before they were discovered by Reiji Okazaki because

A) DNA replicates in the 3'-to-5' direction.
B) single-stranded 5'-to-3' DNA appears behind DNA polymerase.
C) DNA nucleotides are added to the 5' end of the primer on the lagging strand.
D) RNA primase places short RNA primer sequences along the DNA molecule.
E) DNA polymerase I can connect short segments.

Question 54

The molecules that function to replicate DNA in the cell are

A) DNA nucleoside triphosphates.
B) DNA polymerases.
C) nucleoside polymerases.
D) DNAses.
E) ribonucleases.

Question 55

In what way does DNA replication differ in eukaryotes versus prokaryotes?

A) In eukaryotes,synthesis of the new DNA strand is from 3' to 5',whereas in prokaryotes it is from 5' to 3'.
B) In eukaryotes,synthesis of the new DNA strand is from 5' to 3',whereas in prokaryotes it is from 3' to 5'.
C) There are many origins of replication in each eukaryotic chromosome and only one in bacterial DNA.
D) In eukaryotes,synthesis of the new DNA strand is from 5' to 3',whereas in prokaryotes it is random.
E) Okazaki fragments are produced in eukaryotic DNA replication but not in prokaryotic DNA replication.

Question 56

In DNA replication,the processive nature of DNA polymerase

A) increases the number of nucleotides that can be polymerized per enzymatic cycle.
B) holds open the two strands of the DNA molecule for access to the bonds.
C) allows it to jump from one DNA strand to another.
D) temporarily holds the nucleotides together until phosphodiester bonds can form.
E) unwinds the double helix to allow the DNA polymerase to bind.

Question 57

A deoxyribonucleotide is a

A) deoxyribose plus a nitrogenous base.
B) sugar and a phosphate.
C) nitrogenous base bonded at the 5' end to a sugar-phosphate backbone.
D) ribose plus a nitrogenous base.
E) deoxyribose plus a nitrogenous base and a phosphate group.

Question 58

The enzyme DNA ligase is required continuously during DNA replication because

A) fragments of the leading strand must be joined together.
B) fragments of the lagging strand must be joined together.
C) the parental strands must be joined back together.
D) 3'-deoxynucleoside triphosphates must be converted to 5'-deoxynucleoside triphosphates.
E) the complex of proteins that work together at the replication fork must be prevented from falling apart.

Question 59

DNA polymerase lengthens a polynucleotide strand by

A) building short DNA fragments and linking them together.
B) adding lost DNA sequences to the 3' end.
C) linking purines with pyrimidines.
D) threading the existing DNA through a replication complex.
E) covalently linking new nucleotides to a previously existing strand.

Question 60

In eukaryotes,Okazaki fragments are about _______ base pairs long.

A) 5-10
B) 100-200
C) 500-1,000
D) 1,000-2,000
E) 10,000-20,000

Question 61

Starting with a single double-stranded DNA molecule,_______ double-stranded DNA molecules will exist after five rounds of PCR (assuming that the PCR works perfectly).

A) 5
B) 10
C) 16
D) 32
E) 1,024

Question 62

Recall that two hydrogen bonds bind A and T,but three hydrogen bonds bind G and C.The stability of DNA is affected by the number of hydrogen bonds,with more bonds promoting more stability.Double-stranded DNA molecules that have greater stability require more heat to be broken into single strands.Which double-stranded DNA molecules would likely require the lowest temperature in PCR?

A) A molecule with 16 percent A
B) A molecule with 23 percent G
C) A molecule with 30 percent C
D) A molecule with 35 percent T
E) More information is required to answer this question.

Question 63

Mutations are

A) heritable changes in the sequence of DNA bases that always produce an observable phenotype.
B) changes in the nucleotide sequence of DNA that is passed on from one organism to another.
C) mistakes in the incorporation of amino acids into proteins.
D) heritable changes in the mRNA of an organism.
E) nucleotide changes that occur only in gametes.

Question 64

Without DNA repair,the error rate of DNA polymerase is about one for every hundred thousand bases replicated.If an organism has a haploid genome of 2 billion base pairs,how many mutations are likely to occur each time a diploid cell replicates its DNA?

A) 20
B) 40
C) 80
D) 20,000
E) 40,000

Question 65

New sequencing techniques reveal that a child is heterozygous for a new mutation.This mutation appears in all of the cells tested from a variety of tissues (including skin,blood,and hair).The mutation is not found in either the mother or the father.Most likely,this is a new _______ mutation that occurred in _______.

A) somatic;one of the parents
B) somatic;the child
C) germline;one of the parents
D) germline;both of the parents
E) germline;the child

Question 66

Which type of DNA repair system can repair errors in single-stranded DNA?

A) Excision
B) Mismatch
C) Proofreading
D) Telomerase
E) No existing system

Question 67

Under ideal conditions,each round of replication in PCR results in

A) one more double-stranded DNA molecule.
B) two more double-stranded DNA molecules.
C) a doubling of the existing number of DNA molecules.
D) a tripling of the existing number of DNA molecules.
E) no change in the number of DNA molecules.

Question 68

The first repair of mistakes during DNA replication is made by

A) the mismatch repair system.
B) DNA polymerase.
C) excision repair.
D) SOS repair.
E) post-replication repair.

Question 69

Suppose that for a certain gene,nearly 100 percent of the normal level of expression is required to produce the normal phenotype.Based on this requirement,one could predict that a _______ mutation would be _______.

A) gain-of-function;recessive
B) loss-of-function;dominant
C) loss-of-function;recessive
D) nonsense;recessive
E) loss-of-function;a conditional mutation

Question 70

DNA production during PCR can be calculated by the rule of 2ⁿ,where n equals the number of rounds of amplification.Approximately how many rounds of PCR are required to produce a billion DNA molecules from a single molecule,assuming that the PCR works perfectly?

A) 10
B) 20
C) 30
D) 100
E) 1,000

Question 71

The fidelity of eukaryotic DNA replication is astounding.During DNA synthesis,the frequency of errors is about 1 incorrect base in _______ nucleotides inserted.

A) 1,000
B) 5,000
C) 10,000
D) 50,000
E) 100,000

Question 72

In PCR,_______ results in single-stranded DNA template molecules.

A) heat
B) a high salt concentration
C) DNA polymerase
D) an exonuclease
E) a primer

Question 73

You are studying DNA replication using a strain of yeast whose DNA polymerase is reported to have an error rate of 10^-6 bases per cell cycle.However,your analyses of DNA sequences after DNA replication indicate that the error rate is closer to 10^-10.What may explain your results?

A) The yeast expresses high levels of DNA ligase.
B) The yeast has a mismatch repair system.
C) RNA polymerase has high fidelity.
D) The DNA polymerase can tolerate high temperatures.
E) The DNA polymerase is processive.

Question 74

A single hair is found at the scene of a crime.Which technology would you use first to determine if the hair could have come from a certain suspect?

A) PCR
B) DNA sequencing
C) Fragment cloning
D) Probing
E) Antisense RNA

Question 75

Both the father and husband of Queen Victoria of England were not affected by the X-linked disease hemophilia,but her son Leopold was affected,as were many of the royal grandsons and great grandsons who were descended from her daughters.The mutation that caused hemophilia in Leopold and other male descendants probably arose as a _______ mutation in _______.

A) somatic;Victoria's husband,Prince Albert
B) somatic;Queen Victoria
C) germline;Queen Victoria
D) germline;Leopold
E) somatic;Leopold

Question 76

The polymerase chain reaction

A) is a method for sequencing DNA.
B) is used to transcribe specific genes.
C) amplifies specific DNA sequences.
D) does not require DNA replication primers.
E) uses a DNA polymerase that denatures at 55°C and above.

Question 77

Human germline mutations are often considered more worrisome than somatic ones because germline mutations

A) have phenotypic effects,whereas somatic mutations do not.
B) affect more nucleotides than somatic mutations do.
C) are transitions,whereas somatic mutations are transversions.
D) are transmitted to offspring,whereas somatic mutations are not.
E) occur more frequently than somatic mutations.

Question 78

Silent mutations have no effect on amino acid sequences because

A) silent mutations are usually found in noncoding regions of DNA.
B) the genetic code is ambiguous.
C) silent mutations are recessive,and the presence of the dominant allele will result in a functional protein.
D) silent mutations are conditional mutagens,and their phenotypes are altered only under very restrictive conditions.
E) only a single base is involved in a series of thousands of nucleotides.

Question 79

What is the correct order for the following events in excision repair of DNA? (1)DNA polymerase I adds correct bases by 5'to 3' replication.
(2)Damaged bases are recognized.
(3)DNA ligase seals the new strand to existing DNA.
(4)Part of a single strand is excised.

A) 1,2,3,4
B) 2,1,3,4
C) 2,4,1,3
D) 3,4,2,1
E) 4,2,3,1

Question 80

Which statement concerning somatic mutations or germline mutations is true?

A) Somatic mutations occur during sex cell formation.
B) Germline mutations occur during mitosis.
C) Somatic mutations are passed on to sexually produced offspring.
D) Germline mutations are passed on to gametes.
E) Germline mutations are always lethal.