Deck 12: Dna Structure, Replication, and Organization

Question 1

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

Answer 1

B

Question 2

Which nitrogenous bases are considered purines?

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

Answer 2

D

Question 3

For which discovery are Watson and Crick famous?

A)determining the presence of nuclein (DNA) in pus cells
B)determining the three-dimensional structure of DNA
C)determining the role of DNA as the genetic material
D)determining what chemical components are in DNA

Answer 3

B

Question 4

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

Question 5

Which of the following describes the composition of a nucleotide?

A)a five-carbon sugar, a phosphate group, and one of four amino acids
B)a five-carbon sugar, a nitrogenous base, and one of twenty amino acids
C)a five-carbon sugar, a phosphate group, and one of four nitrogenous bases
D)a six-carbon sugar, a phosphate group, and one of twenty amino acids

Question 6

Who was first scientist to identify and characterize DNA?

A)Rosalind Franklin
B)Linus Pauling
C)Francis Crick
D)Friedrich Miescher

Question 7

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 8

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)in none of them
B)in about one-quarter of them
C)in about one-half of them
D)in about three-quarters of them

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

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 11

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 12

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 13

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 14

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 15

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 16

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 17

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 18

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.

Question 19

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 20

Which of the following molecules is a pyrimidine?

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

Question 21

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 22

In the figure, what does the structure labelled C represent?

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

Question 23

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 24

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)three
B)two
C)one
D)none

Question 25

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' ? 5' direction for the leading strand, and the 5' ? 3' direction on the lagging strand
B)in the 5' ? 3' direction only
C)in the 5' ? 3' direction for the leading strand, and the 3' ? 5' direction on the lagging strand
D)in either the 5' ? 3' direction or the 3' ? 5' direction on both strands, depending on where replication begins

Question 26

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 27

In the figure, what does the structure labelled A represent?

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

Question 28

In the figure, what does the structure labelled D represent?

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

Question 29

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 30

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

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

Question 31

In the figure, what does the structure labelled B represent?

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

Question 32

In the figure, what does the structure labelled E represent?

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

Question 33

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 34

Why is DNA replication said to be semiconservative?
a.because half of the DNA in a cell comes from one parent and half comes from the other parent
b.because the number of nucleotides within genes remains constant
c.because each new DNA molecule is composed of one old strand and one new strand
d.because the same process of DNA replication is used by all organisms

Question 35

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' ? 5' direction.
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 36

The figure depicts the results of an experiment to determine how DNA replication occurs. What is the apparent composition of each DNA molecule after replication?

A)one old DNA strand and one new DNA strand
B)entirely old DNA
C)some DNA helix regions that are old DNA, alternating with some DNA regions that are new DNA
D)entirely new DNA

Question 37

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 38

Suppose that a cell has a genetic mutation such that the primase enzyme is unable to make RNA primers. Also, assume that all of the other enzymes directly involved in DNA replication are still functional in these cells. How much of the process of DNA replication would you expect to see in these cells?
a.None; no part of the DNA replication process could occur.
b.Both the leading and lagging strand would be synthesized, but Okazaki fragments would not be joined together.
c.The DNA helix would be unwound by helicase, but no new strands would be produced.
d.The leading strand would be synthesized, but not the lagging strand.

Question 39

Why do many antiviral drugs resemble nucleotides?

A)because they inhibit DNA ligase
B)because they are easily obtained
C)because they inhibit DNA polymerase
D)because they are isolated from plants

Question 40

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 41

Which phrase best describes nucleosomes?

A)eukaryotic DNA associated with histone proteins
B)eukaryotic DNA associated with nonhistone proteins
C)prokaryotic DNA associated with nonhistone proteins
D)prokaryotic DNA associated with histone proteins

Question 42

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 43

Individuals with Xeroderma pigmentosum inherit a faulty DNA repair mechanism. How does this disorder manifest in a patient?

A)The patient is sterile.
B)The Okazaki fragments produced during DNA replication cannot join.
C)No proofreading occurs during DNA replication.
D)The patient easily develops skin cancer when exposed to sunlight.

Question 44

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 45

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 46

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 47

Which enzymes perform proofreading during DNA replication?

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

Question 48

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 49

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 50

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 51

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

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

Question 52

What does chromatin consist of?

A)RNA and protein
B)DNA and protein
C)DNA and RNA
D)DNA only

Question 53

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 54

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 55

How do histones bind to DNA?

A)by an ionic attraction to the nitrogenous bases of DNA
B)by hydrogen bonding with the nitrogenous bases of DNA
C)by hydrogen bonding to the deoxyribose sugars of DNA
D)by an ionic attraction to the phosphate groups of DNA

Question 56

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 57

Which cells in a multicellular organism generally contain inactive telomerases?

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

Question 58

What is the length of the DNA contained in the nucleus of a typical human cell?

A)about 2 km
B)about 100 m
C)about 2 m
D)about 10 mm

Question 59

What type of charge do histones tend to carry?

A)a mixture of positive and negative charges
B)no charge
C)a negative charge
D)a positive charge

Question 60

What is the ultimate source of variability in offspring?

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

Question 61

Why do prokaryotic genomes not require telomerases?

A)because they are circular
B)because they contain fewer genes
C)because they are small
D)because they are relatively simple

Question 62

Match each researcher or set of researchers with the discovery or experiment each is associated with.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 63

Acyclovir is a chemical analogue of a DNA nucleoside that is used to treat people who are infected by herpes simplex viruses (HSV). How does acyclovir work as a treatment without harming the patient?

Question 64

Match each researcher or set of researchers with the discovery or experiment each is associated with.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

Question 65

What does the rolling circle model of replication refer to?

A)transfer of plasmid DNA from one cell to another
B)transfer of genomic DNA from one cell to another
C)all bacterial DNA replication
D)the multiple replication bubbles seen in prokaryotes

Question 66

What type of condensed DNA are Barr bodies (inactivated X chromosomes) composed of?

A)nucleosomes
B)heterochromatin
C)euchromatin
D)10-nm chromatin fibres

Question 67

Match each researcher or set of researchers with the discovery or experiment each is associated with.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 68

The electron micrograph in the figure shows chromatin organized like beads on a string. Which histone protein is usually associated with the "string" portion?

A)histone H1
B)histone H2A
C)histone H3
D)histone H4

Question 69

What is the nucleosome core particle composed of?

A)histones H2A, H2B, H3, and H4
B)single-stranded binding proteins
C)histones H1 and H2A
D)histones H3 and H4

Question 70

Which of the following items associated with DNA packaging is the thickest?

A)an H2A histone protein
B)a nucleosome
C)a DNA double helix
D)a solenoid

Question 71

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 72

Match each researcher or set of researchers with the discovery or experiment each is associated with.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 73

Which structure is formed when histone H1 associates with linker DNA and the nucleosome?
a.euchromatin
b.the 10-nm chromatin fibre
c.heterochromatin
d.the solenoid

Question 74

Match each researcher or set of researchers with the discovery or experiment each is associated with.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