Quiz 5 Bio 285

Which of the following are important in reducing the errors in DNA replication in E. coli organisms? Select one: a. All of these choices minimize errors in DNA replication in E. coli. b. nucleotide excision repair c. mismatch repair d. proofreading activity of the epsilon subunit of DNA polymerase III

a. All of these choices minimize errors in DNA replication in E. coli.

Which nucleotide-bound tubulin would you find at the plus end of a depolymerizing microtubule? Select one: a. GDP-tubulin b. GTP-tubulin

a. GDP-tubulin

What is the function of microtubule-associated proteins (MAPS)? Select one: a. MAPS bind to the surface of microtubules, stabilizing or destabilizing the microtubule structure. b. MAPS digest degraded actin molecules. c. MAPS are motor proteins that transport cargo along microtubules. d. MAPS are enzyme receptors attached to microtubules that are important in several signal transduction pathways.

a. MAPS bind to the surface of microtubules, stabilizing or destabilizing the microtubule structure.

Researchers found E. coli that had mutation rates 100 times higher than normal. What is a possible explanation for these results? Select one: a. The proofreading mechanism of DNA polymerase was not working properly. b. The DNA polymerase was unable to add bases to the 3' end of the growing nucleic acid chain. c. There were one or more mismatches in the RNA primer. d. The single-stranded binding proteins were malfunctioning.

a. The proofreading mechanism of DNA polymerase was not working properly.

When nucleotides polymerize to form a nucleic acid _____. Select one: a. a covalent bond forms between the sugar of one nucleotide and the phosphate of a second b. a hydrogen bond forms between the sugar of one nucleotide and the phosphate of a second c. hydrogen bonds form between the bases of two nucleotides d. covalent bonds form between the bases of two nucleotides

a. a covalent bond forms between the sugar of one nucleotide and the phosphate of a second

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? Select one: a. decreased ability to repair certain DNA mutations b. increased rate of formation of pyrimidine dimers c. decreased rate of repair of pyrimidine dimers d. increased rate of repair of pyrimidine dimers

a. decreased ability to repair certain DNA mutations

Hydrolysis of GTP to GDP on microtubules: Select one: a. leads to depolymerization of the microtubule. b. drives the movement of motor proteins. c. provides the energy for movement of the axoneme. d. is necessary for polymerization of the tubulin subunits.

a. leads to depolymerization of the microtubule. Correct

In a nucleic acid polymer, the hydrogen bonds that help to hold regions of double-strandedness together occur between what parts of the nucleotide monomers? Select one: a. nitrogenous bases b. sugars, phosphates, and nitrogenous bases c. sugars d. sugars and phosphates

a. nitrogenous bases

DNA replication is highly accurate. It results in about one mistake per billion nucleotides. For the human genome (contains about 3 billion base pairs), how often would errors occur? Select one: a. on average, 6 times each time the entire genome of a cell is replicated b. on average, once every 6 cell divisions c. on average, once or twice in the lifetime of an individual d. on average, once a lifetime in 10% of the population

a. on average, 6 times each time the entire genome of a cell is replicated

Nucleotide excision repair _____. Select one: a. recognizes and repairs thymine dimers in DNA b. repairs single-strand breaks in DNA c. recognizes and removes mismatched bases d. corrects errors in nucleotide excision Feedback

a. recognizes and repairs thymine dimers in DNA

What provides the energy for the polymerization reactions in DNA synthesis? Select one: a. the deoxyribonucleotide triphosphate substrates b. breaking the hydrogen bonds between complementary DNA strands c. DNA polymerase d. ATP

a. the deoxyribonucleotide triphosphate substrates

Which of the following would be most likely to cause DNA damage in an individual suffering from xeroderma pigmentosum? Select one: a. ultraviolet lights b. incandescent lightbulbs c. Fluorescent light bulbs Feedback

a. ultraviolet lights

How is the structure of kinesin related to its function? Select one: a. Kinesin has two heads to attach to the vesicle being moved, and a tail region that attaches to microtubules. b. Kinesin has a tail region that binds to vesicles and two heads that can attach to microtubules. c. Kinesin has two intertwined polypeptides that make up the stalk and enable it to contract and shorten. d. The kinesin tail has an ATP binding site to fuel its activities. Feedback

b. Kinesin has a tail region that binds to vesicles and two heads that can attach to microtubules.

The epsilon (ε) subunit of DNA polymerase III of E. coli has exonuclease activity. How does it function in the proofreading process? Select one: a. The epsilon subunit excises a segment of DNA around the mismatched base. b. The epsilon subunit can remove a mismatched nucleotide. c. It adds nucleotide triphosphates to the 3' end of the growing DNA strand. d. The epsilon subunit can recognize which strand is the template or parent strand, and which is the new strand of DNA.

b. The epsilon subunit can remove a mismatched nucleotide.

What is the difference between the leading strand and the lagging strand in bacterial DNA replication? Select one: 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 is synthesized continuously in the 5`->3` direction, while the lagging strand is synthesized discontinuously in the 5`->3` direction. c. There are different types of DNA polymerases involved in elongation of the leading strand and the lagging strand. d. The leading strand requires an RNA primer, whereas the lagging strand does not.

b. The leading strand is synthesized continuously in the 5`->3` direction, while the lagging strand is synthesized discontinuously in the 5`->3` direction.

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? Select one: a. These mutations have resulted from translocation of gene segments. b. There are several enzymes involved in the nucleotide excision repair process. c. There are seven genes that produce the same protein. d. These seven genes are the most easily damaged by ultraviolet light. Feedback

b. There are several enzymes involved in the nucleotide excision repair process.

Dynein and kinesin: Select one: a. create the crawling motion typical of amoeba. b. are motor proteins that generate movements associated with microtubules. c. are the two subunits of microtubules. d. are motor proteins that generate sliding of the sarcomere.

b. are motor proteins that generate movements associated with microtubules. Correct

The condensation reaction that forms nucleic acid polymers occurs between a _____ group on one nucleotide and a _____ group on a second nucleotide. Select one: a. nitrogenous base, nitrogenous base b. phosphate, hydroxyl c. carbon, carbon d. nitrogenous base, sugar

b. phosphate, hydroxyl

DNA is synthesized through a process known as _____. Select one: a. transcription b. semiconservative replication c. conservative replication d. translation

b. semiconservative replication

The primers used for DNA synthesis are _____. Select one: a. proteins that bind to single-stranded DNA b. short RNA sequences c. short amino acid sequences (peptides) d. short DNA sequences

b. short RNA sequences

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. Select one: a. 1, 2, 3, 4, 5 b. 3, 2, 1, 5, 4 c. 2, 1, 3, 5, 4 d. 3, 1, 2, 4, 5

c. 2, 1, 3, 5, 4

Nucleic acids have a definite polarity, or directionality. Stated another way, one end of the molecule is different from the other end. How are these ends described? Select one: a. One end has a hydroxyl group on the 2 carbon; the other end has a hydrogen atom on the 2 carbon. b. One end contains a nitrogenous base; the other end lacks it. c. One end has an unlinked 3 carbon; the other end has an unlinked 5 carbon. d. One end has one phosphate group; the other end has two phosphate groups. Feedback

c. One end has an unlinked 3 carbon; the other end has an unlinked 5 carbon.

What does it mean to say that strands in a double helix are antiparallel? Select one: a. They each have a 5' -> 3' directionality b. They each have a sugar-phosphate backbone. c. They have an opposite directionality, or polarity. d. Their primary sequences consist of a sequence of complementary bases.

c. They have an opposite directionality, or polarity.

Cytoskeletal filaments that display "dynamic instability:" Select one: a. move around in the cytoplasm with a whip-like motion. b. constantly slide past each other. c. change in length due to polymerization or depolymerization. d. tend to make the cytoplasm dynamically unstable.

c. change in length due to polymerization or depolymerization. Correct

If a segment of DNA contains 28 percent T nucleotides, then the percentage of A nucleotides in that segment will be _____. Select one: a. 22 percent b. 56 percent c. 44 percent d. 28 percent

d. 28 percent

Microtubule Structure, Function and Dynamics) What happens to the end of a microtubule causing it to change from a state of polymerization to depolymerization? Select one: a. GDP binding b. GTP binding c. GDP hydrolysis d. GTP hydrolysis

d. GTP hydrolysis

Microtubules serve all of the following functions in cells, EXCEPT: Select one: a. Microtubules mediate the movements of chromosomes during mitosis. b. They help to control movements of subcellular particles. c. They are the primary structural component of flagella. d. Microtubules are the "thick filaments" of sarcomeres.

d. Microtubules are the "thick filaments" of sarcomeres.

Which statement about motor proteins is false? Select one: a. Kinesin moves along the microtubule in the plus direction, whereas dynein moves in the minus direction. b. The rate of movement of kinesin and dynein along the microtubule is determined primarily by the ATPase domain of the proteins. c. Motor proteins are the driving force behind movements generated by cilia and flagella. d. There is very little diversity in motor proteins within the animal kingdom.

d. There is very little diversity in motor proteins within the animal kingdom.

Kinesin is a(n) ____________ Select one: a. enzyme b. GTPase c. ATPase d. more than one of the choices given

d. more than one of the choices given Correct

The _________ end of the microtubule binds the gamma-tubulin ring complex. Select one: a. Both b. Plus c. Minus

minus

Taxol is a chemotherapeutic drug that _______________ microtubules. Select one: a. stabilizes b. prevents polymerization of c. destabilizes Feedback

stabilizes

The error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair Select one: True False

True

Which nucleotide-bound tubulin would you find at the microtubule "cap"? Select one: a. GTP-tubulin b. GDP-tubulin

a. GTP-tubulin

Which nucleotide-bound tubulin would you find at the plus end of a growing microtubule? Select one: a. GTP-tubulin b. GDP-tubulin

a. GTP-tubulin

The mitotic spindle is composed of actin filaments Select one: True False

false

MAPs and motors can both stabilize and destabilize microtubules. Select one: True False

true