Deck 13: Dna Structure and Replication

Question 1

How were the rough locations of genes and chromosomal processes such as crossing over first visualized in detail?

A) by X-ray mutagenesis of Neurospora chromosomes
B) by isolating chromosomes from the pea plants used by Mendel
C) using unusual, abnormally large chromosomes from Drosophila
D) using X-ray crystallography to examine chromosome structure
E) by examining mutations in sperm and egg chromosomes

Answer 1

using unusual, abnormally large chromosomes from Drosophila

Question 2

How are X rays used in the technique of X-ray crystallography?

A) The scattering of X rays by a purified form of a molecule reveals its structure.
B) DNA strands are separated by X-ray energy, revealing the order of bases.
C) Cells are broken open to release chromosomes by being bombarded with X rays.
D) The X rays are used to mutate DNA, to determine the location of genes.
E) Enzymes are destroyed by X rays, revealing the order of steps in metabolism.

Answer 2

The scattering of X rays by a purified form of a molecule reveals its structure.

Question 3

Watson and Crick:

A) relied heavily on the experimental results of others.
B) did extensive experimentation.
C) were unaware that others were also seeking the structure of DNA.
D) had strong evidence that DNA was a protein.
E) were hired by laboratories specifically to study DNA.

Answer 3

relied heavily on the experimental results of others.

Question 4

Watson and Crick discovered:

A) that DNA is made of nucleotides.
B) that DNA is the genetic material.
C) X-ray crystallography.

Question 5

All of the following are bonds found in DNA molecules except:

A) phosphate to deoxyribose.
B) deoxyribose to adenine.
C) cytosine to guanine.
D) cytosine to phosphate.
E) thymine to adenine.

Question 6

What parts of a chromosome specify the amino acid sequence of a protein?

A) the types of bonds
B) the pattern of sugars
C) the sequence of bases
D) the pattern of phosphates

Question 7

What units are bonded together to make a strand of DNA?

A) proteins
B) enzymes
C) cells
D) nucleotides
E) chromatids

Question 8

What is the relationship between DNA and proteins?

A) Genes are made of proteins that encode the base sequence of DNA.
B) DNA encodes for proteins, and protein enzymes replicate and maintain DNA.
C) DNA makes up the individual sugar-phosphate-base units of a protein.
D) DNA molecules are the enzymes that maintain chromosomes made of protein.
E) Proteins make up the individual sugar-phosphate-base units of DNA.

Question 9

What is one way that incorrect nucleotides are removed from a newly synthesized molecule of DNA?

A) Crossing over replaces regions with DNA errors with new segments of DNA.
B) DNA ligases both remove and replace incorrectly positioned nucleotides.
C) Any DNA strand with an error is destroyed, and an entire new strand is synthesized.
D) DNA polymerases remove incorrect nucleotides and replace them with correct ones.
E) DNA ligases remove incorrect nucleotides for replacement by DNA polymerases.

Question 10

Imagine that the DNA replication error rate for a repair-deficient E. coli is 1 in 10 million. If the E. coli genome is 5 million nucleotide pairs, how often will the E. coli genome sustain a mutation in this strain, keeping in mind that both strands of a DNA molecule are replicated at once?

A) once every five cell divisions
B) once per cell division
C) twice per cell division
D) four times per cell division
E) once every ten cell divisions

Question 11

What is the relationship between any two strands of DNA?

A) An A base on one always pairs with a G base on the other.
B) They are a pair of sister chromatids.
C) They are connected to each other by sugar-phosphate bonds.
D) One was the template for the synthesis of the other.
E) They have identical base sequences.

Question 12

One strand of DNA is the template for the synthesis of another strand. What does this mean?

A) A strand of DNA is taken apart to supply nucleotides for synthesis of a new strand.
B) One strand of DNA acts as a wedge to separate other strands before replication.
C) The template specifies the bases on the nucleotides of the strand being made.
D) The new strand will have exactly the same base sequence as the template strand.
E) A strand of DNA is the enzyme that connects nucleotides in replication.

Question 13

What happens to the two strands of a DNA molecule that gets replicated?

A) After serving as replication templates, the two old strands are rejoined.
B) After serving as replication templates, the two old strands are destroyed.
C) Nucleotides from the old strands are randomly incorporated into the new strands.
D) Incomplete segments of the old strands end up in each newly synthesized strand.
E) Each old strand ends up paired with a newly synthesized strand.

Question 14

Refer to the figure above and then answer the question that follows.

-What are the base pairing rules of DNA?

A) A pairs with T; G pairs with C.
B) A pairs with C; T pairs with G.
C) A pairs with G; T pairs with C.

Question 15

Refer to the figure above and then answer the question that follows.

-If DNA were a single-stranded molecule instead of a double-stranded one, what function(s) of DNA would be much more difficult to carry out?

A) the ability to use DNA sequences to code for amino acids
B) replication
C) repair of mistakes in DNA sequence

Question 16

If two alleles are possible for a single gene,

A) the sequences of the DNA for each allele would be different and produce different proteins.
B) the sequences of the DNA would be different for each allele, but they would produce identical proteins.
C) the sequences of the DNA would be identical for each allele, but they would produce different proteins.
D) the sequences of the DNA would be identical for each allele and would produce identical proteins.

Question 17

If you could add a colored label to each strand of a DNA molecule then follow the colored label in the DNA molecules that result from replication of the original DNA, in the two new molecules you would see:

A) colored label on both strands of one of the DNA molecules and no label on either strand of the other DNA molecule.
B) colored label in one strand only of each of the DNA molecules.
C) no colored label in either DNA molecule.
D) a zebra-striped pattern of some patches with color and some patches without on each molecule.
E) colored label on both stands of both DNA molecules.

Question 18

Given all the bad things that mutations do, it seems counterintuitive that a low rate of mutation is actually good. What good could possibly come of mutation?

A) Mutation is essential if populations are to evolve over time.
B) Mutation is needed for DNA to encode proteins.
C) Mutation is needed when we are fighting an infection.
D) Mutation is essential to prevent cancer.
E) Mutation is needed if DNA is ever to be replicated.

Question 19

The average mutation rate for DNA replication is 1 mutation for every 10 billion (10,000,000,000) nucleotides of DNA replicated. Yet DNA polymerase makes a mistake during replication at an average of 1 in 100,000 nucleotides. What does this say about DNA replication?

A) Most errors in DNA replication become mutations.
B) The base pairing rules (A pairs with T and G pairs with C) prevent any mutations.
C) Cells are extraordinarily proficient at repairing errors made during DNA replication.
D) No errors in DNA replication become mutations
E) All errors in DNA replication become mutations.

Question 20

Cancer is a disease caused by mutations. Yet in most instances if one of your parents tragically died from cancer, this does not put you at greater risk than a person whose parents do not develop cancer. How can cancer be caused by mutations and yet not be heritable?

A) Mutations caused by environmental agents such a tobacco smoke cannot be inherited.
B) The mutations that cause cancer are special and cannot be passed on regardless of what type of cell they occur in.
C) Most cancers arise from mutations in germ line cells.
D) Most cancers arise from mutations in somatic cells.
E) Cancer-causing mutations are repaired in offspring but not in parents.

Question 21

The observation that cancer incidence increases sharply with age was one of the first clues that multiple mutations had to accumulate in one cell before cancer arose. If only one mutation were needed to occur in a single cell for cancer to develop, and if the probability of acquiring a mutation is assumed to be a constant that does not change with age, what would you predict to be the relationship between cancer incidence and age?

A) Cancer rate would be higher at younger ages and lower at older ages.
B) Cancer incidence would increase even more sharply with age than it actually does.
C) Cancer rate would increase linearly with age (a plot of cancer incidence versus age would give a straight line with positive slope; the line "goes uphill").
D) Cancers would never occur.
E) Cancer rate would not change with age.

Question 22

If mutations lead to cancerous cells, why don't most point mutations immediately make a cell cancerous?

A) Cancer-causing changes are accompanied by compensating cancer-reducing changes.
B) Point mutations are not passed from parent to daughter cells in cell division.
C) All point mutations occur in germ-line cells, which do not become cancerous.
D) Multiple mutations are required to make a malignant cancer cell.
E) Point mutations rarely occur in genes.

Question 23

Refer to the figure above and then answer the question that follows.

-Which of the following choices is an example of a point mutation?

A) failure of a chromosome to complete replication
B) pairing of a G on one strand of DNA with a C on the other
C) loss or gain of a chromosome
D) pairing of a G on one strand of DNA with a T on the other
E) failure of a chromosome to be replicated

Question 24

Refer to the figure above and then answer the question that follows.

-Which of the following choices is an example of a mutation?

A) a place in DNA where the base sequence has been permanently changed
B) an altered compound in the Neurospora pathway that synthesizes amino acids
C) an incompletely replicated piece of DNA
D) an agent that damages DNA, such as X rays
E) a strand of DNA that is not paired with a complementary strand

Question 25

Refer to the figure above and then answer the question that follows.

-How do most mutations affect an organism?

A) They affect a single cell but are not passed on to other cells.
B) They have no effect or are harmful.
C) They kill the organism.
D) They create cancerous cells.
E) They are beneficial and create a more adapted organism.

Question 26

Refer to the figure above and then answer the question that follows.

-What is the difference between whole-chromosome aberrations and point mutations?

A) Point mutations are not permanent changes in the DNA; aberrations are permanent.
B) Aberrations are not permanent changes in the DNA; point mutations are permanent.
C) Point mutations are the loss of parts of chromosomes; aberrations are the loss of whole chromosomes.
D) Point mutations affect a single location in the genome; aberrations affect a large section.

Question 27

What is the relationship between mutations and cancer?

A) Cells do not require mutations to become cancerous but acquire them as they divide.
B) Cells lose the ability to mutate their DNA and evolve once they become cancerous.
C) Some mutations cause cells to lose control over cell division.
D) Any point mutation will cause a cell to start proliferating without control.
E) Only a mutation can stop a cell once it becomes cancerous.

Question 28

A point mutation:

A) always harms the cell that has one.
B) occurs at the end of chromosomes.
C) involves only one base or base pair.
D) cannot be repaired.
E) is a rare event.

Question 29

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L. The following data are generated by providing these compounds to the mutants.
Data: All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.

-How many enzymes are in the pathway, from the one that modifies the first compound to the one whose product is amino acid L?

A) 4
B) 7
C) 5
D) 3
E) 6

Question 30

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L. The following data are generated by providing these compounds to the mutants.
Data: All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.

-The order in which the molecules are converted in the pathway is:

A) A, C, B, L.
B) B, C, A, L.
C) C, B, A, L.
D) B, A, C, L.
E) C, A, B, L.

Question 31

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L. The following data are generated by providing these compounds to the mutants.
Data: All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.

-Beadle and Tatum's accomplishment was to show that:

A) DNA is a double helix.
B) amino acids are synthesized by metabolic pathways.
C) genes encode for the production of protein enzymes.
D) chromosomes are made of DNA.
E) DNA nucleotides have four different bases.

Question 32

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L. The following data are generated by providing these compounds to the mutants.
Data: All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.

-George Beadle and Edward Tatum were awarded the Nobel prize for their work on:

A) crossing over in the large chromosomes of Drosophila.
B) how X rays damage DNA to cause mutations.
C) genetics of pea plants.
D) the structure of DNA.
E) the one-gene, one-enzyme hypothesis.

Question 33

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L. The following data are generated by providing these compounds to the mutants.
Data: All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.

-Beadle and Tatum:

A) realized that mutations in genes caused defective enzymes.
B) experimented with a fungus called Neurospora.
C) formulated the "one-gene, one enzyme"hypothesis.
D) used X rays to cause mutations.
E) did all of the above.

Question 34

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L.
The following data are generated by providing these compounds to the mutants.
Data:
All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.

-Each strain has a mutation in a different gene whose product is an enzyme in the production of amino acid L.

Question 35

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L.
The following data are generated by providing these compounds to the mutants.
Data:
All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.

-The compound B requires only one modification, by one enzyme, to be converted to L.

Question 36

Match the scientist and the approximate time frame (decades) of their work with their achievements.

-Modeled the molecular structure of DNA

A) James Watson and Francis Crick, 1950s
B) George Beadle and Edward Tatum, 1930s and 1940s
C) Rosalind Franklin and Maurice Wilkins, 1950s

Question 37

Match the scientist and the approximate time frame (decades) of their work with their achievements.

-Generated X-ray crystallography images of DNA

A) James Watson and Francis Crick, 1950s
B) George Beadle and Edward Tatum, 1930s and 1940s
C) Rosalind Franklin and Maurice Wilkins, 1950s

Question 38

Match the scientist and the approximate time frame (decades) of their work with their achievements.

-Correlated the production of one enzyme with one gene

A) James Watson and Francis Crick, 1950s
B) George Beadle and Edward Tatum, 1930s and 1940s
C) Rosalind Franklin and Maurice Wilkins, 1950s

Question 39

Suppose covalent bonds where used to hold two DNA strands together. What sort of problem would this pose for the double helix?

Question 40

How do new gene alleles appear?

Question 41

A certain organism's genetic material is composed of 21 percent thymine. What percentage of guanine does this organism have?

Question 42

Individuals who have a disease such as melanoma do not necessarily have offspring with melanoma. Why is this?