BIO CH 14

Suppose a new species of bacteria was found that contained a form of DNA polymerase III that can add new nucleotides to either the 5' end or the 3' end of an existing strand. All other properties of the DNA polymerase III enzyme remain unchanged. In addition, these bacteria contain all of the other enzymes and proteins relevant to DNA synthesis that are found in E. coli. How would DNA replication in these new bacteria differ from replication in E. coli? A. Both new strands could be synthesized continuously B. Both new strands could be synthesized discontinuously C. DNA pol I would no longer be required for replication D. DNA ligase would no longer be required for replication

A. Both new strands could be synthesized continuously

During DNA replication, which enzyme removes the RNA primers and then fills in the gap? A. DNA polymerase I B. DNA primase C. DNA polymerase III D. DNA ligase

A. DNA polymerse I

Suppose a new form of DNA polymerase III is discovered that does not require a primer to begin synthesis of a new strand. All other properties of the enzyme remain unchanged. If this new enzyme were to be expressed in the same organism that normally expresses DNA polymerase III, what would no longer be necessary to completely replicate all of the cellular DNA? A. DNA polymerase I B. Telomerase C. DNA ligase D. DNA helicase E. Single-strand binding protein

A. DNA polymerse I

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder. Patients with XP exhibit a cellular hypersensitivity to ultraviolet (UV) radiation, a high incidence of skin cancer and premature aging. Based on these clinical characteristics, what is the most likely cause for this disease? A. Defects in DNA repair B. Defects in DNA replication C. Lack of telomerase activity D. Shortened telomeres

A. Defects in DNA repair

Who demonstrated that phage genetic material is DNA and not protein? A. Hershey and Chase B. Chargaff C. Franklin D. Watson and Crick E. Avery, MacLeod, and McCarty

A. Hershey and Chase

Why does DNA polymerase I carry the number one? A. It was the first polymerase isolated from E. coli. B. It is the first polymerase to be activated during DNA replication. C. It is the only polymerase that has both 3' to 5' and 5' to 3' exonuclease activity. D. It is the smallest polymerase.

A. It was the first polymerase isolated from E. coli

Which enzyme adds new nucleotides to the end of a growing strand? A. Ligase B. Polymerase C. Gyrase D. Helicase E. Endonuclease

A. Ligase

The double helix model of DNA structure was proposed by A. Watson and Crick. B. Griffith. C. Avery. D. Franklin. E. Chargaff.

A. Watson and Crick

The lagging strand is replicated with a series of Okazaki fragments and that is why its synthesis is considered to be A. discontinuous. B. continuous. C. bidirectional. D. antiparallel. E. semiconservative.

A. discontinuous

Information obtained by Franklin from X-ray crystallography on DNA suggested that it is shaped like a A. helix. B. ribbon. C. hollow cylinder. D. pleated sheet. E. icosahedron.

A. helix

Viruses that attack bacteria are called A. phages. B. proviruses. C. virulent. D. lytic.

A. phages

The site where the two original DNA strands are separated and active replication occurs is called the A. replication fork. B. replisome. C. primosome. D. lagging strand. E. sliding clamp subunit.

A. replication fork

If a mutation produced helicase that was unable to hydrolyze ATP, DNA replication would be A. slowed down. B. speeded up. C. unaffected. D. more prone to errors.

A. slowed down

In DNA, a purine must always pair with a pyrimidine and vice versa in order to ensure that A. the distance between the two phosphodiester backbones remains constant. B. the two strands are antiparallel. C. the distance between one base pair and the next remains constant. D. each base pair is held together by three hydrogen bonds.

A. the distance between the two phosphodiester backbones remains constant

The synthesis of a growing strand of DNA is carried out by adding nucleotides to which end of an existing strand? A. 2' B. 3' C. 5' D. 1'

B. 3'

Deoxyribose has a carbon atom that is not part of the pentose ring. In a nucleotide, what is attached to this carbon? A. A nitrogenous base B. A phosphate group C. Three hydrogen atoms D. One hydrogen atom

B. A phosphate group

Chargaff's rules for the pairing of nitrogen bases is A. A = C and G = T. B. A = T and G = C. C. A = G and C = T. D. A+T = G+C.

B. A=T and G=C

Who proposed that in any DNA molecule, A =T and G = C? A. Hershey and Chase B. Chargaff C. Franklin D. Watson and Crick

B. Chargaff

This is the genetic material for all cellular organisms and some viruses. A. RNA B. DNA C. Protein D. Chromatin

B. DNA

In 1952, Hershey and Chase confirmed Avery's (1944) conclusion that A. proteins are the repositories for hereditary information. B. DNA is the repository for hereditary information. C. RNA is the repository for hereditary information. D. each DNA molecule is composed of two strands that are twisted into a double helix. E. the replication of DNA is semiconservative.

B. DNA is the repository for hereditary information

You are asked to participate in a clinical trial for a new drug that can activate telomerase. What would be a likely risk of taking such a drug? A. Decreased capacity for tissue repair B. Increased vulnerability to cancer C. Premature aging D. Decreased telomere length

B. Increased vulnerability to cancer

You take a sample of bacteria with DNA that contains only 14N and allow these cells to replicate in a medium that contains only 15N. After 3 rounds of replication, what percent of the DNA molecules will contain one strand with only 14N and one strand with only 15N? Enter your answer as a whole number without the percent sign. For example, 5% would be entered as 5 and 37% would be entered as 37. __________

25

Each origin of replication in eukaryotic cells is recognized by an origin recognition complex, which allows the assembly of the pre-replicative complex including the replicative helicase. This complex ultimately allows the recruitment of DNA polymerase. After DNA polymerase is recruited to an origin and replicates the DNA in that region during S phase, the replicative helicase cannot be loaded onto the DNA in that region again until early G1 due to a variety of regulatory mechanisms. Why is it important that, once used, the replicative helicase cannot be loaded onto the DNA again until G1 of the cell cycle? A. This ensures that multiple origins must be used to replicate the DNA in all cellular chromosomes. B. This ensures that DNA cannot be replicated again in that region until the next cell cycle. C. This ensures that telomeres on all chromosomes will be replicated properly. D. This ensures that DNA repair processes can only take place during G1 of the cell cycle.

B. This ensures that DNA cannot be replicated again in that region until the next cell cycle

In DNA, complementary nitrogen bases are held together by A. nitrogen bonds. B. hydrogen bonds. C. hydrophobic bonds. D. peptide bonds. E. phosphodiester bonds.

B. hydrogen bonds

What is the correct sequence for DNA replication in E. coli? A. initiation, termination, elongation B. initiation, elongation, termination C. elongation, termination, initiation D. elongation, initiation, termination

B. initiation, elongation, termination

Genetic analysis indicates that an unknown organism contains a gene that codes for a defective form of telomerase. Based on this information alone, you can conclude that this organism A. is prokaryotic. B. is eukaryotic. C. has unusually long telomeres. D. has an increased risk of developing cancer.

B. is eukaryotic

The method of DNA replication, where each original strand is used as a template to build a new strand, is called the A. conservative method. B. semiconservative method. C. disruptive method. D. continuous method. E. replication and amplification method.

B. semiconservative method

When a mixture of live nonvirulent bacteria and dead virulent bacteria was injected into mice, Griffith unexpectedly found that the injected mice died. He explained this result by suggesting that the nonvirulent bacteria are being A. activated. B. transformed. C. translated. D. transcribed. E. expressed.

B. transformed

DNA replication always proceeds by adding new bases to which end of an existing strand? A. 1' B. 2' C. 3' D. 4' E. 5'

C. 3'

If a short sequence of DNA is 5' AATTGCCGT 3', its complement is A. 5' AAAACGCCA 3'. B. 3' TTAACGGCT 5'. C. 3' TTAACGGCA 5'. D. 3' TTAAGCCGA 5'. E. 5' TTAACGGCA 3'.

C. 3' TTAACGGCA 5'

Nucleotides have a phosphate group attached at which carbon atom of the sugar? A. 2' B. 3' C. 5' D. 1'

C. 5'

Endonucleases and exonucleases are enzymes that can remove nucleotides from a polynucleotide chain. Where do endonucleases and exonucleases remove nucleotides from? A. An endonuclease removes nucleotides from the 5' end of the chain; an exonuclease removes nucleotides from the 3' end of the chain. B. An endonuclease removes nucleotides from the 3' end of the chain; an exonuclease removes nucleotides from the 5' end of the chain. C. An endonuclease removes nucleotides interally; an exonuclease removes nucleotides from the ends of the chain. D. An endonuclease removes nucleotides from the ends of the chain; an exonuclease removes nucleotides internally.

C. An endonuclease removes nucleotides internally; an exonuclease removes nucleotides from the ends of the chain

Avery and his coworkers showed that the agent responsible for changing nonvirulent bacteria into virulent bacteria was A. protein. B. polysaccharide. C. DNA. D. RNA. E. lipid.

C. DNA

Based on their experiment with T2 bacteriophages, Hershey and Chase concluded that A. DNA replication is semiconservative. B. the phage coat contains the genetic material. C. DNA functions as the genetic material. D. A always pairs with T and G always pairs with C. E. virulent bacteria can transform nonvirulent bacteria.

C. DNA functions as the genetic material

As the two strands of DNA are unraveled, which enzyme relieves the strain on the two strands? A. DNA polymerase B. DNA ligase C. DNA gyrase D. DNA endonuclease E. DNA exonuclease

C. DNA gyrase

During replication, which enzyme unwinds the DNA double helix? A. DNA primase B. DNA polymerase I C. DNA helicase D. DNA gyrase E. DNA ligase

C. DNA helicase

Who provided X-ray diffraction photographs of purified DNA fibers that suggested a helical structure with a consistent diameter of about 2 nm and a complete helical turn every 3.4 nm? A. Hershey and Chase B. Chargaff C. Franklin D. Watson and Crick

C. Franklin

In Griffith's experiments, A. mice infected with live nonvirulent bacteria developed pneumonia and died. B. nonvirulent bacteria transformed the virulent bacteria into a nonvirulent variety. C. mice infected with heat-killed virulent bacteria and live nonvirulent bacteria developed pneumonia and died. D. mice infected with heat-killed virulent bacteria and heat-killed nonvirulent bacteria developed pneumonia and died.

C. Mice infected with heat-killed virulent bacteria developed pneumonia and died

You decide to repeat the Meselson-Stahl experiment, except this time you plan to grow the cells on light 14N medium for many generations and then transfer them to heavy 15N medium and allow them to grow for 2 additional generations (2 rounds of DNA replication). If the semiconservative model of DNA replication is correct, what is the expected distribution of DNA in the density gradient after two rounds of replication? A. One band of intermediate density B. One band of intermediate density and one band of light density C. One band of intermediate density and one band of heavy density D. One band of heavy density and one band of light density E. One band of heavy density

C. One band of intermediate density and one band of heavy density

You are performing an experiment to study replication of DNA on a specific yeast chromosome. Yeast cells were synchronized in G1 and were released into S phase. DNA was recovered every five minutes after release into S phase, and an analysis was done to look for DNA replication in specific regions of the yeast chromosome. Assume that these regions of the yeast chromosome are adjacent to each other in the following order: Region A, Region B, Region C, Region D. The data below indicate the times during which DNA replication was observed in each of these regions. Using these data, which region or regions of the yeast chromosome most likely contained an origin of replication? Times When DNA Replication Was Observed in Each Region: Region A: 40 minutes, 45 minutes, and 50 minutes Region B: 35 minutes, 40 minutes and 45 minutes Region C: 30 minutes, 35 minutes, and 40 minutes Region D: 35 minutes, 40 minutes, and 45 minutes A. Region A B. Region B C. Region C D. Region D E. Regions A, B, C and D

C. Region C

The two strands of a DNA molecule contain nitrogen bases which are A. identical. B. parallel. C. complementary. D. proportionate. E. random.

C. complementary

Watson and Crick developed a model of DNA in which the two strands twist into the shape of a ________________. A. circle B. helix C. double helix D. double pleated sheet

C. double helix

After attaching to a bacterial cell, a bacteriophage typically A. injects protein into the cell. B. extracts protein from the cell. C. injects DNA into the cell. D. extracts DNA from the cell. E. transforms the cell into a virulent strain.

C. injects DNA into the cell

After DNA replication is complete, each strand of the original molecule is bound to a new complementary strand. This process is known as A. disruptive replication. B. conservative replication. C. semiconservative replication. D. dispersive replication. E. stabilizing replication.

C. semiconservative replication

After a long week of sunbathing on the beach, what type of DNA damage should you be most concerned about? A. photolyase-induced mutations B. decreased telomere length C. thymine dimers D. activation of uvr A, B, and C genes

C. thymine dimers

If 14% of the nucleotides from a DNA molecule contain the base T, what percent will contain the base G? A. 14% B. 18% C. 28% D. 36% E. 72%

D. 36%

What DNA sequences is complementary to 5' ATGGTCAGT 3'? A. 5' ATGGTCAGT 3' B. 5' TGACTGGTA 3' C. 5' TACCAGTCA 3' D. 5' ACTGACCAT 3'

D. 5' ACTGACCAT 3'

In which cells would you expect to find the highest level of telomerase? A. Muscle cells B. Oocytes C. Neurons D. Cells that replenish the lining of the gut

D. Cells that replenish the lining of the gut

Who originally discovered the process of bacterial transformation? A. Watson and Crick B. Chargaff C. Hershey and Chase D. Griffith E. Meselson and Stahl

D. Griffith

You decide to repeat the Meselson-Stahl experiment, except this time you plan to grow the cells on light 14N medium for many generations and then transfer them to heavy 15N medium and allow them to grow for 2 additional generations (2 rounds of DNA replication). If the conservative model of DNA replication is correct, what is the expected distribution of DNA in the density gradient after one round of replication? A. One band of intermediate density B. One band of light density C. One band of heavy density D. One band of light density and one band of heavy density E. One band of light density and one band of intermediate density

D. One band of light density and one band of heavy density

If a mutation prevented synthesis of the beta subunit of DNA pol III, which would be most affected? A. DNA unwinding B. Formation of RNA primers C. Formation of the replication fork D. Processivity E. Removal of RNA primers

D. Processivity

If we think of the DNA double helix as a twisted ladder, what makes up the rungs or steps of the ladder? A. Phosphate groups only B. Alternating phosphate groups and sugars C. Sugars only D. Purines and pyrimidines E. Phosphate groups and bases

D. Purines and pyrimidines

You are working with a strain of E. coli that has a mutation in the DNA polymerase II gene, such that the encoded protein is exonuclease deficient, but is otherwise normal. How do you predict that this would most likely affect the activity of this enzyme? A. This mutation would prevent the ability of DNA polymerase II to engage in lagging strand synthesis. B. This mutation would prevent the ability of DNA polymerase II to form phosphodiester bonds between nucleotides. C. This mutation would prevent the ability of DNA polymerase II to remove RNA nucleotides in the 5' to 3' direction. D. This mutation would prevent the ability of DNA polymerase II to remove DNA nucleotides that are damaged.

D. This mutation would prevent the ability of DNA polymerse II to remove DNA nucleotides that are damaged

Who proposed that the structure of DNA is a double helix with two polynucleotide chains running in opposite directions and held together by hydrogen bonding between pairs of nitrogenous bases? A. Hershey and Chase B. Chargaff C. Franklin D. Watson and Crick E. Meselson and Stahl

D. Watson and Crick

Either strand of a DNA molecule can be used as a template to reconstruct the other because the two strands of a DNA molecule are ________ . A. identical B. antiparallel C. bound D. complementary

D. complementary

Griffith, a British microbiologist, used bacteria and mice to demonstrate the process of transformation. During transformation, A. a bacterial chromosome produces an exact copy of itself. B. the nucleus of a mouse cell repairs itself when damaged by bacterial infection. C. DNA from an infected mouse cell changes bacteria from a non-pathogenic to a pathogenic form. D. genetic material is transferred from one bacterial cell to another. E. a bacterial cell is transformed into a spore during unsuitable environmental conditions.

D. genetic material is transferred from one bacterial cell to another

DNA consists of two antiparallel strands of nucleotides held together by A. peptide bonds. B. covalent bonds. C. ionic bonds. D. hydrogen bonds.

D. hydrogen bonds

The chemical bond connecting one nucleotide with the next along one strand of a DNA molecule is called a A. glycosidic bond. B. hydrogen bond. C. phosphate bond. D. phosphodiester bond. E. peptide bond.

D. phosphodiester

Replication of DNA is A. conservative. B. redundant. C. dispersive. D. semiconservative. E. semidispersive.

D. semiconservative

You are asked to give a classroom demonstration of DNA supercoiling. To do so, you take two different colored pieces of rubber tubing, twist them very tightly and excessively around each other and join the ends of the tubing appropriately. Next, you relieve the supercoiling by breaking one strand and unwinding it. In this demonstration, the breaking and unwinding to relieve the supercoiling simulates the action of A. exonucleases. B. polymerases. C. ligases. D. topoisomerases. E. primases.

D. topoisomerases

Eukaryotic organisms speed up the process of DNA replication by A. shortening the initiation phase. B. producing several sliding clamp complexes which provide more binding sites for DNA pol III. C. using DNA gyrase to unravel the double helix rather than DNA helicase. D. using multiple origins of replication on each chromosome.

D. using multiple origins of replication on each chromosome

If 16% of the nucleotides in one strand of a DNA molecule contain the base G, what percent of the nucleotides on the complementary strand will also contain the base G? A. 16% B. 8% C. 34% D. 32% E. Impossible to determine from the information given.

E. Impossible to determine from the information given

During DNA replication, DNA pol III synthesizes the lagging strand in segments, called A. replication fragments. B. Chargaff's segments. C. repeating primers. D. replisomes. E. Okazaki fragments.

E. Okazaki fragments

During DNA replication, each new strand begins with a short A. amino acid primer. B. lipid primer. C. hydrophilic primer. D. DNA primer. E. RNA primer.

E. RNA primer

DNA primase A. creates a short RNA primer that is complementary to an RNA template. B. creates a short DNA primer that is complementary to an RNA template. C. creates a short DNA primer that is complementary to a DNA template. D. creates a short DNA template that is complementary to an RNA primer. E. creates a short RNA primer that is complementary to a DNA template.

E. creates a short RNA primer that is complementary to a DNA template.

The replisome has two main subcomponents. They are A. the replication fork and the sliding clamp subunit. B. the primosome and the sliding clamp subunit. C. the replication fork and the DNA pol III enzymes. D. the DNA pol III enzymes and the sliding clamp subunits. E. the primosome and the DNA pol III enzymes.

E. the primosome and the DNA pol III enzymes