Deck 14: Dna and the Gene: Synthesis and Repair

Question 1

What can you infer from the information presented in this table?

A)DNA polymerase I and DNA polymerase III are the same enzyme found in different organisms.
B)DNA polymerase I and DNA polymerase III have different functions.
C)The sliding clamp molecule is a ribozyme.
D)Topoisomerase is involved in proofreading activity.

Answer 1

B

Question 2

Put the following steps of DNA replication in chronological order. 1. Single-stranded binding proteins attach to DNA strands.
2) Hydrogen bonds between base pairs of antiparallel strands are broken.
3) Primase binds to the site of origin.
4) DNA polymerase binds to the template strand.
5) An RNA primer is created.

A)1,2,3,4,5
B)2,1,3,5,4
C)3,2,1,5,4
D)1,2,3,4,4

Answer 2

B

Question 3

The fact that within a double-stranded DNA molecule,adenine forms two hydrogen bonds with thymine and cytosine forms three hydrogen bonds with guanine is known as

A)semi-conservative replication.
B)complementary base pairing.
C)secondary structure of a DNA molecule.
D)a double helix.

Answer 3

B

Question 4

Figure 14.3
Refer to Figure 14.3.Which of the structures in the figure breaks hydrogen bonds between complementary bases?

Question 5

Hershey and Chase set out to determine what molecule served as the unit of inheritance.They completed a series of transduction experiments in which E.coli was infected by a T2 virus.Which molecular component of the T2 virus actually ended up inside the cell?

A)protein
B)carbohydrate
C)lipid
D)DNA

Question 6

What is a major difference between eukaryotic DNA replication and prokaryotic DNA replication?

A)Prokaryotic replication does not require a primer.
B)Prokaryotic chromosomes have a single origin of replication,while eukaryotic chromosomes have multiple origins of replication.
C)DNA polymerase III of eukaryotes has both endonuclease and exonuclease activity,while that of prokaryotes has only exonuclease activity.
D)DNA polymerases of prokaryotes can add nucleotides to both 3′ and 5′ ends of DNA strands,while those of eukaryotes function only in the 5′→3′ direction.

Question 7

Semiconservative replication involves a template.What is the template?

A)single-stranded binding proteins
B)DNA polymerase contains the template needed
C)one strand of the DNA molecule
D)an RNA molecule

Question 8

How does the simple primary and secondary structure of DNA hold the information needed to code for the many features of multicellular organisms?

A)The hydrogen bonding among backbone constituents carries coded information.
B)The base sequence of DNA carries all the information needed to code for proteins.
C)The covalent bonding among backbone constituents contains the information that is passed from generation to generation.
D)The amino acids that make up the DNA molecule contain the information needed to make cellular proteins.

Question 9

Who performed the classic experiments that proved DNA was copied by semiconservative replication?

A)Watson and Crick
B)Meselson and Stahl
C)Hershey and Chase
D)Franklin and Wilkins

Question 10

DNA contains the template needed to copy itself,but as you learned in Chapter 4,it has no catalytic activity.What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed?

A)ribozymes
B)DNA polymerase
C)ATP
D)deoxyribonucleotide triphosphates

Question 11

The transduction experiments done by Hershey and Chase,and the transformation experiments done by Griffith,supported the same conclusion,which was that

A)pathogenic molecules affect the health of all living organisms.
B)DNA is the molecular substance of genetic inheritance.
C)organisms must be sacrificed for science to progress.
D)genetic recombination in living organisms is rare.

Question 12

Figure 14.2
Identify the lagging strand in Figure 14.2.

A)a
B)b
C)c
D)d

Question 13

What provides the energy for the polymerization reactions in DNA synthesis?

A)ATP
B)DNA polymerase
C)breaking the hydrogen bonds between complementary DNA strands
D)the deoxyribonucleotide triphosphate substrates

Question 14

Watson and Crick elucidated the structure of DNA in 1953.Their research built on and helped explain the findings of other scientists,including

A)X-ray diffraction studies by Rosalind Franklin and Maurice Wilkins.
B)Chargaff's rules: C = G and T = A.
C)Scientists who recognized that a nucleotide consisted of a sugar,a phosphate,and a nitrogen-containing base.
D)All of the above were important considerations in the elucidation of the structure of DNA.

Question 15

What is the difference between the leading strand and the lagging strand in DNA replication?

A)The leading strand is synthesized in the 3′→5′ direction in a discontinuous fashion,while the lagging strand is synthesized in the 5′→3′ direction in a continuous fashion.
B)The leading strand requires an RNA primer,whereas the lagging strand does not.
C)The leading strand is synthesized continuously in the 5′→3′ direction,while the lagging strand is synthesized discontinuously in the 5′→3′ direction.
D)There are different DNA polymerases involved in elongation of the leading strand and the lagging strand.

Question 16

Figure 14.2
In Figure 14.2,which is the template strand?

A)a
B)b
C)c
D)d

Question 17

Figure 14.3
Refer to Figure 14.3.Which structure is responsible for stabilizing DNA in its single-stranded form?

Question 18

In the polymerization of DNA,a phosphodiester bond is formed between a phosphate group of the nucleotide being added and ________ of the last nucleotide in the polymer.

A)ATP
B)C₆
C)the 3′ OH
D)a nitrogen from the nitrogen-containing base

Question 19

Figure 14.1
Refer to Figure 14.1.What bases will be added to the primer as DNA replication proceeds? The bases should appear in the order that they will be added.

A)C,A,G,C,A,G,A
B)T,C,T,G,C,T,G
C)A,G,A,C,G,A,C
D)U,G,U,C,G,U,C

Question 20

DNA is synthesized through a process known as

A)semiconservative replication.
B)conservative replication.
C)dispersive replication.
D)transcription.

Question 21

If DNA repair mechanisms fail,what is the result?

A)a mutation
B)a defective enzyme
C)cancer
D)All of the above can result from the failure of DNA repair mechanisms.

Question 22

In the mismatch repair process,enzyme complexes replace bases that were incorrectly inserted into the newly synthesized DNA strand.To function,they must be able to distinguish between the parent DNA strand and the new strand.How is this accomplished?

A)The new strand contains the diphosphate bases.
B)The parent strand is methylated.
C)The new strand contains ribose sugars.
D)The parent strand is usually radiolabeled.

Question 23

What are pyrimidine dimers?

A)pyrimidines (C and T)that have gained an extra nitrogen-containing ring structure
B)pyrimidines on antiparallel DNA strands that form complementary base pairs
C)adjacent pyrimidines on the same DNA strand that join by covalent bonding
D)pyrimidines formed by demethylation of purines

Question 24

In humans,xeroderma pigmentosum is a disorder of the nucleotide excision repair mechanism.These individuals are unable to repair DNA damage caused by ultraviolet light.Which of the following are the most prominent types of mutations in individuals suffering from xeroderma pigmentosum?

A)mismatch errors
B)telomere shortening
C)methylation of purines
D)pyrimidine dimers

Question 25

Where would Okazaki fragments be found in the image above? Note: The black boxes represent RNA primers and the polarities of the template strands are indicated.

A)A,B
B)C,D
C)A,C
D)B,D
E)A,D

Question 26

In a healthy cell,the rate of DNA repair is equal to the rate of DNA mutation.When the rate of repair lags behind the rate of mutation,what is a possible fate of the cell?

A)The cell can be transformed to a cancerous cell.
B)The cell differentiates to form a different,but vital tissue.
C)The process of differentiation of cells that takes place in embryonic development is dependent on a higher rate of DNA mutation than the rate of DNA repair.
D)DNA synthesis will continue in an attempt to repair itself.

Question 27

Which of the following agents can cause mutations in DNA?

A)aflatoxins that are found in moldy grains
B)free radicals that are formed as by-products of aerobic respiration
C)ultraviolet radiation from sunlight
D)All of the above are mutagenic agents.

Question 28

Researchers found E.coli that had mutation rates 100 times higher than normal.What is a possible explanation for these results?

A)The single-stranded binding proteins were malfunctioning.
B)There were one or more mismatches in the RNA primer.
C)The proofreading mechanism of DNA polymerase was not working properly.
D)The DNA polymerase was unable to add bases to the 3′ end of the growing nucleic acid chain.

Question 29

DNA replication is highly accurate.It results in about one mistake per billion nucleotides.For the human genome,how often would errors occur?

A)on average,once or twice in the lifetime of an individual
B)on average,6 times each time the entire genome of a cell is replicated
C)on average,once every 6 cell divisions
D)on average,once a lifetime in 10% of the population

Question 30

If during the process of DNA replication,the enzyme topoisomerase was not functioning (i.e.it was mutated)what do you expect will happen to the replication process?

A)The double helix would not begin to unwind at all.
B)The double helix would begin to unwind but this unwinding would stop prematurely due to over-twisting of the DNA.
C)The double helix would unwind completely but no primers would be added to the template strand.
D)The double helix would unwind completely but no new strand would be created due to the formation of secondary structures.

Question 31

The epsilon (ε)subunit of DNA polymerase III of E.coli has exonuclease activity.How does it function in the proofreading process?

A)The epsilon subunit can remove a mismatched nucleotide.
B)The epsilon subunit excises a segment of DNA around the mismatched base.
C)The epsilon subunit can recognize which strand is the template or parent strand,and which is the new strand of DNA.
D)It adds nucleotide triphosphates to the 3′ end of the growing DNA strand.

Question 32

What is a telomere?

A)the mechanism that holds two sister chromatids together
B)the reorganization of the cell nucleus that takes place during telophase
C)the site of origin of DNA replication
D)the ends of linear chromosomes

Question 33

Which of the following cells do not have active telomerase activity?

A)most normal somatic cells
B)most normal germ cells
C)most cancer cells

Question 34

Hereditary nonpolyposis colorectal cancer (HNPCC)is an inherited disorder.The genetic defect identified is an error in the mismatch repair mechanism.Which of the following would be an expected result of this mutation?

A)increased rate of errors by wild-type DNA polymerase
B)increased rate of formation of pyrimidine dimers
C)increased rate of repair of pyrimidine dimers
D)decreased ability to repair certain DNA mutations

Question 35

Bodnar et al.(1998)used telomerase to extend the life span of normal human cells.Telomere shortening puts a limit on the number of times a cell can divide.How might adding telomerase affect cellular aging?

A)Telomerase will speed up the rate of cell proliferation.
B)Telomerase ensures that the ends of the chromosomes are accurately replicated and eliminates telomere shortening.
C)Telomerase shortens telomeres and thus delays cellular aging.
D)Telomerase would have no effect on cellular aging.

Question 36

Recent studies have shown that xeroderma pigmentosum (an error in the nucleotide excision repair process)can result from mutations in one of seven genes.What can you infer from this finding?

A)There are seven genes that produce the same protein.
B)These seven genes are the most easily damaged by ultraviolet light.
C)There are several enzymes involved in the nucleotide excision repair process.
D)These mutations have resulted from translocation of gene segments.

Question 37

Which of the following would be least likely to cause DNA damage in an individual suffering from xeroderma pigmentosum?

A)natural lighting
B)low-level ultraviolet lights
C)incandescent light bulbs
D)reflected sunlight

Question 38

Telomere shortening is a problem in which types of cells?

A)prokaryotes
B)eukaryotes
C)both prokaryotes and eukaryotes

Question 39

Which of the following are important in reducing the errors in DNA replication in E.coli organisms?

A)proofreading activity of the epsilon subunit of DNA polymerase III
B)mismatch repair
C)nucleotide excision repair
D)All of the above minimize errors in DNA replication in E.coli.