Deck 11: DNA Structure, Replication, and Repair

Question 1

Which type of molecule was the ³²P used to label in the Hershey Chase experiment?

A) a DNA molecule
B) a protein molecule
C) a RNA molecule
D) a phospholipid molecule

Answer 1

A

Question 2

What happens when living R strain Streptococcus pneumoniae bacteria are mixed with heat-killed S strain Streptococcus pneumoniae bacteria?

A) The S strain bacteria are transformed into R strain bacteria.
B) The S strain bacteria come back to life.
C) The R strain bacteria are killed, and the S strain bacteria remain dead.
D) The R strain bacteria are transformed into S strain bacteria.

Answer 2

D

Question 3

Which nitrogenous bases are considered purines?

A) thymine and cytosine
B) adenine and cytosine
C) thymine and adenine
D) adenine and guanine

Answer 3

D

Question 4

Suppose that the DNA of an organism is studied and found to contain 30% adenine. Based on this information, what percentage of thymine would you predict that the DNA of this organism would also contain?

A) 20%
B) 30%
C) 40%
D) 50%

Question 5

How are adjacent nucleotides on a strand of DNA connected to each other?

A) by a hydrophobic interaction
B) by a phosphodiester bond
C) by a peptide bond
D) by a hydrogen bond

Question 6

What were the T2 bacteriophages used in the Hershey and Chase experiment made of?

A) RNA and protein
B) DNA and protein
C) protein, phospholipid, and DNA
D) DNA

Question 7

Which of the following molecules is a pyrimidine?

A) guanine
B) phosphate
C) uracil
D) adenine

Question 8

Suppose that the DNA of an organism is studied and found to contain 14% guanine. What percentage of thymine would you expect to find?

A) 14%
B) 28%
C) 36%
D) 72%

Question 9

Which nitrogenous bases are considered pyrimidines?

A) adenine and guanine
B) thymine and adenine
C) adenine and cytosine
D) thymine and cytosine

Question 10

If protein was the genetic material, where in the Hershey and Chase experiment would you expect to find radioactivity when phage contained ³⁵S-labelled protein?

A) in the bacterial cell
B) in the phage progeny
C) in the phage spikes
D) in the phage coat

Question 11

Suppose that you performed a version of the Hershey and Chase experiment, this time using ³²P-labelled viruses that insert their DNA into the DNA of the cells that they infect. Also suppose that the viral DNA is then treated as part of the cell's own DNA, and is replicated during DNA replication and passed on to daughter cells when the cell divides. You infect a population of cells with the ³²P-labelled viruses, and then let the infected cells go through two generations of cell divisions. In how many cells should you find ³²P-labelled DNA?

A) 0%
B) about 25%
C) about 50%
D) about 75%

Question 12

Why are fossils of woolly mammoths important for learning about genetic material?

A) They provide useful data about permafrost.
B) They provide useful data to understand extinction.
C) They provide useful morphological data.
D) They provide useful samples of ancient molecules.

Question 13

Prior to 1940, which type of molecule did scientists consider to be the best candidate for the genetic material?

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

Question 14

Which of the following nucleotide sequences represents the complementary sequence that would bind to the DNA strand 5'-GACGTT-3'?

A) 3'-TCATGG-5'
B) 3'-CTGCAA-5'
C) 3'-AGTACC-5'
D) 5'-TCATGG-3'

Question 15

In the Hershey and Chase experiment, why was the pellet radioactive after bacteria had been infected with ³²P-labelled viruses and centrifuged?

A) The bacteria had incorporated radioactive proteins into their cell membranes.
B) The virus particles had incorporated radioactive proteins from the bacterial DNA.
C) The bacteria had incorporated radioactive DNA.
D) The bacteria had incorporated radioactive proteins into their DNA.

Question 16

Which of the following techniques did Wilkins and Franklin use to study the structure of DNA?

A) electron microscopy
B) X-ray diffraction
C) molecular scale models of nucleotides
D) computer-assisted graphics

Question 17

How are the two strands in DNA's double helix held to each other?

A) by hydrophobic interactions
B) by hydrogen bonds
C) by ionic bonds
D) by phosphodiester bonds

Question 18

From his work with Streptococcus pneumoniae bacteria, Griffith described the transforming principle. What did this principle prove to be?

A) a polysaccharide capsule
B) a phospholipid
C) protein
D) DNA

Question 19

The complete genome has been sequenced from an old horse. How old is this genome?

A) 500 000 years
B) 700 000 years
C) 800 000 years
D) 900 000 years

Question 20

Which of the following describes the composition of a nucleotide?

A) a 5-carbon sugar, a phosphate group, and 1 of 4 amino acids
B) a 5-carbon sugar, a nitrogenous base, and 1 of 20 amino acids
C) a 5-carbon sugar, a phosphate group, and 1 of 4 nitrogenous bases
D) a 6-carbon sugar, a phosphate group, and 1 of 20 amino acids

Question 21

Figure 11-2
In Figure 11-2, what does the structure labelled D represent?

A) single-stranded binding protein
B) DNA ligase
C) primase
D) helicase

Question 22

Which of the following is correct about DNA replication?

A) DNA on a chromosome is never replicated continuously along its entire length.
B) DNA on a chromosome is replicated discontinuously at both ends of the replication fork.
C) DNA on a chromosome is replicated continuously at both ends of the replication fork.
D) DNA on a chromosome is replicated continuously at one fork but discontinuously at the other fork.

Question 23

What is meant by the term antiparallel, when applied to DNA structure?

A) The 5' end of one strand is directly paired with the 5' end of the other strand.
B) The double helix twists; it is not perfectly parallel.
C) The 5' end of one strand is directly paired with the 3' end of the other strand.
D) One strand has a negative charge, and the other strand has a positive charge.

Question 24

Reiji Okazaki discovered that "Okazaki fragments" are produced during DNA replication. What are Okazaki fragments?

A) short lengths of new DNA on the leading strand
B) RNA primers on both the lagging and leading strand
C) RNA primers on the lagging strand
D) short lengths of new DNA on the lagging strand

Question 25

Figure 11-2
In Figure 11-2, what does the structure labelled A represent?

A) single-stranded binding protein
B) helicase
C) DNA polymerase
D) DNA ligase

Question 26

Which process provides the energy needed for DNA replication?

A) the breaking of the hydrogen bonds between base pairs
B) the DNA polymerase
C) the unwinding of the DNA double helix
D) the hydrolysis of pyrophosphate

Question 27

What closes nicks between DNA fragments, forming a covalent bond that ties or joins the fragments together?

A) DNA ligase
B) helicase
C) topoisomerase
D) primase

Question 28

Which sentence describes the width of a DNA double helix?

A) The width is greater where purines are present than where pyrimidines are present.
B) The width is narrower where adenine is present than where cytosine is present.
C) The width is constant.
D) The width varies randomly.

Question 29

Figure 11-2
In Figure 11-2, what does the structure labelled E represent?

A) primase
B) single-stranded binding protein
C) DNA ligase
D) helicase

Question 30

Suppose that a mistake made during DNA replication in a cell is not corrected, but instead the mutation remains in the single strand where it occurred. Then suppose that after the cell divides, both daughter cells survive, and those cells then go on to have DNA replication, and ultimately cell division. Four cells now exist where there once was one cell. Assume that the mistake was never corrected and that no other mistakes occurred. How many of the four cells will have the mutation in their DNA?

A) 3
B) 2
C) 1
D) 0

Question 31

Figure 11-2
In Figure 11-2, what does the structure labelled C represent?

A) helicase
B) single-stranded binding protein
C) primase
D) DNA ligase

Question 32

Figure 11-2
In Figure 11-2, what does the structure labelled B represent?

A) primase
B) helicase
C) DNA polymerase
D) DNA ligase

Question 33

Which sentence best explains why, during DNA replication, DNA ligase is most active on the lagging strand?

A) The lagging strand requires DNA ligase to couple the RNA primer to the Okazaki fragments.
B) The lagging strand synthesizes DNA in the 3'
C) The lagging strand is synthesized more slowly, and DNA ligase speeds up the DNA polymerase.
D) The lagging strand contains more short DNA segments than the leading strand, and these short segments are joined together by DNA ligase.

Question 34

Which of the following describes the direction in which nucleotides are added onto a growing DNA strand during DNA replication in cells?

A) in the 3'
B) in the 5'
C) in the 5'
D) in either the 5'

Question 35

What catalyzes the unwinding of the DNA double helix during DNA replication?

A) topoisomerase
B) primase
C) DNA polymerase
D) helicase

Question 36

When RNA primers are added, what do they provide to DNA polymerase that is essential to its function?

A) a free 3' OH
B) partially double stranded DNA
C) RNA
D) a free 5' phosphate

Question 37

Which of the following acts to remove twisting and strain ahead of the replication fork during DNA replication?

A) primase
B) topoisomerase
C) helicase
D) DNA polymerase

Question 38

Which of the following assembles a short RNA chain as the first nucleotides in a new DNA strand?

A) DNA polymerase
B) primase
C) topoisomerase
D) helicase

Question 39

What adds individual nucleotides to the 3' end of an existing strand to build a new DNA strand during DNA replication?

A) topoisomerase
B) primase
C) helicase
D) DNA polymerase

Question 40

Why does DNA replication proceed continuously on the leading strand and discontinuously on the lagging strand?

A) because DNA polymerase synthesizes DNA in only one direction
B) because DNA ligase operates in only one direction
C) because DNA polymerase contains more than one subunit
D) because DNA polymerase synthesizes DNA in two directions

Question 41

Match each researcher or set of researchers with the discovery or experiment each is associated wit
h.
a.Watson and Crick
b.Avery, MacLeod, and McCarty
c.Frederick Griffith
d.Hershey and Chase
e.Meselson and Stahl
showed that DNA is the transforming principle, from heat-killed S strain Streptococcus pneumoniae that can make the R strain virulent

Question 42

What is the ultimate source of variability in offspring?

A) Okazaki fragments
B) DNA repairs
C) nucleosomes
D) mutations

Question 43

Suppose that DNA repair enzymes cut out part of a DNA strand that had an incorrect nucleotide. Which two enzymes are needed to complete the repair?

A) DNA polymerase and primase
B) DNA polymerase and DNA ligase
C) primase and sliding clamp
D) primase and DNA ligase

Question 44

More than 90% of cancer cells have fully active telomerase enzymes. Explain how that might play a role in enabling cancer cells to keep rapidly dividing.

Question 45

What are replisomes? Explain their function.

Question 46

How do DNA repair enzymes typically find mismatched base pairs?

A) by scanning for Okazaki fragments
B) by scanning for distortions in the newly synthesized chain
C) by scanning for missing hydrogen bonds
D) by scanning for unsealed nicks in the DNA strands

Question 47

Match each researcher or set of researchers with the discovery or experiment each is associated wit
h.
a.Watson and Crick
b.Avery, MacLeod, and McCarty
c.Frederick Griffith
d.Hershey and Chase
e.Meselson and Stahl
worked out the double helix model for DNA structure

Question 48

During normal DNA replication, why is part of the DNA at the ends of linear chromosomes NOT copied into the new DNA strands?

A) because DNA ligase cannot join pieces at the end of a chromosome
B) because RNA primers at the beginning of a new strand cannot be replaced with DNA
C) because those ends are Okazaki fragments that are lost
D) because cells do not need the DNA at the ends of chromosomes

Question 49

What is the function of telomerase in humans?

A) to add telomere repeats in all human cells
B) to add telomere repeats in some human cells
C) to remove telomere repeats in all human cells
D) to remove telomere repeats in some human cells

Question 50

What would be the error rate in DNA replication if the proofreading ability of DNA polymerase were to be removed?

A) 1 error in 10 000 000 to 100 000 000 nucleotides
B) 1 error in 100 000 to 1 000 000 nucleotides
C) 1 error in 1000 to 10 000 nucleotides
D) 1 error in 10 to 100 nucleotides

Question 51

Match each researcher or set of researchers with the discovery or experiment each is associated wit
h.
a.Watson and Crick
b.Avery, MacLeod, and McCarty
c.Frederick Griffith
d.Hershey and Chase
e.Meselson and Stahl
showed that DNA replication in Escherichia coli is semiconservative

Question 52

Which enzymes perform proofreading during DNA replication?

A) DNA ligase
B) DNA polymerase
C) primase
D) telomerase

Question 53

Suppose you take a cell from an adult cow and attempt to produce a clone of that cow. Also suppose that, for some reason, telomerase is NOT functioning in that cell or in any cell that comes from it. What would you expect to happen with the clone?

A) The lack of telomerase should have no effect on the clone.
B) When the clone grows up, it will most likely have cancer.
C) The cell will never be able to divide at all.
D) The cell may divide, but after a certain number of divisions, cell division will stop.

Question 54

Which cells in a multicellular organism most likely contain inactive telomerases?

A) somatic cells
B) embryonic cells
C) germ line cells
D) immune cells

Question 55

Match each researcher or set of researchers with the discovery or experiment each is associated wit
h.
a.Watson and Crick
b.Avery, MacLeod, and McCarty
c.Frederick Griffith
d.Hershey and Chase
e.Meselson and Stahl
showed that the genetic material of bacteriophage T2 is DNA

Question 56

Where are telomeres located?

A) within genes
B) in the middle of chromosomes
C) at the ends of a chromosome
D) at replication origins

Question 57

Match each researcher or set of researchers with the discovery or experiment each is associated wit
h.
a.Watson and Crick
b.Avery, MacLeod, and McCarty
c.Frederick Griffith
d.Hershey and Chase
e.Meselson and Stahl
showed that a transforming principle from heat-killed S strain Streptococcus pneumoniae could be used to make the R strain virulent