exam 3

Refer to VS Map: Cellular Communities—Mitotic Cell Division Tour. At the end of M phase for a single cell, how many daughter cell(s) are present? 4 2 3 1

2

A new nucleotide can only be added to the _____ end of a growing DNA strand. DNA therefore always grows in the _____ direction. 5'; 3' to 5' 5'; 5' to 3' 3'; 5' to 3' 3'; 3' to 5'

3'; 5' to 3'

A diploid plant species has 16 chromosomes. How many chromosomes are in a tetraploid "version" of this plant? In the hexaploid? In the octoploid? 32 in the tetraploid, 48 in the hexaploid, and 56 in the octoploid 16 in the tetraploid, 24 in the hexaploid, and 32 in the octoploid 12 in the tetraploid, 18 in the hexaploid, and 24 in the octoploid 32 in the tetraploid, 48 in the hexaploid, and 64 in the octoploid

32 in the tetraploid, 48 in the hexaploid, and 64 in the octoploid

Approximately what percentage of the human genome consists of repetitive DNA or transposable elements? 25 percent 10 percent 50 percent 5 percent 1 percent

50 percent

Only 2.5 percent of the human genome actually codes for proteins. The other 97.5 percent includes: All of other answer options are correct. introns. repetitive DNA. templates for noncoding RNA.

All of other answer options are correct.

What is the result of DNA ligase's action? DNA transcription occurs.DNA translation occurs. DNA is condensed to chromosomes. DNA is broken up at specific sites. DNA fragments are joined together.

DNA fragments are joined together.

The enzyme responsible for proofreading a growing DNA strand and for replacing mismatched nucleotides is helicase. topoisomerase II. DNA polymerase. DNA replicase. DNA ligase.

DNA polymerase.

Ras is most similar to: the β (beta) subunit of three-subunit G proteins. the α (alpha) subunit of three-subunit G proteins. the γ (gamma) subunit of three-subunit G proteins. ion channels. receptor kinases.

the α (alpha) subunit of three-subunit G proteins.

What is the function of the enzyme DNA polymerase? to synthesize a polypeptide using DNA as a template to synthesize a strand of DNA using a polypeptide as a template to synthesize a strand of mRNA using mRNA as a template to synthesize a strand of DNA using DNA as a template to synthesize a strand of mRNA using DNA as a template

to synthesize a strand of DNA using DNA as a template

Which enzyme relieves the tension on the double helix during DNA replication? helicase a single-stranded binding protein DNA polymerase an RNA primer topoisomerase

topoisomerase

Refer to Animation: Somatic Mutations in Cancer. Mutations arise in which order in the colon cancer example shown in the animation? Ras, APC, p53 p53, Ras, APC APC, p53, Ras APC, Ras, p53

APC, Ras, p53

You are a cancer biologist analyzing a patient's sample of cancer cells and blood. You already sequenced the genes that encode the signaling molecule proteins and detected no mutations associated with cancer (in other words, the proteins fold into the expected tertiary structures). However the cells' signaling transduction cascade is over-active, and as a result they divide rapidly. Which of the following hypotheses regarding your observations would you test? The concentration of a signaling molecule in the patient is higher than usual. The cells taken from the patient exhibit a reduced ability to amplify the signal. The cells taken from the patient have more growth factor receptors than normal. Both A and C A, B and C

Both A and C

Transposable elements are: DNA sequences that can insert themselves into new positions within the genome. proteins that can move between cells. None of the other answer options is correct. proteins that can move in and out of the nucleus. DNA sequences that can insert themselves into RNA.

DNA sequences that can insert themselves into new positions within the genome.

Refer to VS Map: Cellular Communities—Responding to Cellular Signals Tour. Consider the steps in activation of a cellular response.I. Protein kinase A is activated.II. Ligand binds to G protein-coupled receptor.III. ATP is converted into cAMP.IV. The alpha subunit of the G protein activates adenylyl cyclase.V. GDP is replaced by GTP in the G protein.In what order do the steps for the activation of a cellular response take place? V > I > III > II > IV IV > II > V > I > III III > IV > I > V > II II > V > IV > III > I I > III > II > IV > V

II > V > IV > III > I

Refer to Animation: Somatic Mutations in Cancer. When p53 becomes mutant in cells already mutant for APC and Ras, what occurs? These cells survive despite DNA damage and divide extremely rapidly. These cells expand their chromosome number to 53. These cells die. These cells remain benign.

These cells survive despite DNA damage and divide extremely rapidly.

Refer to VS Map: Cellular Communities—Responding to Cellular Signals Tour. Predict what happens if each adenylyl cyclase enzyme is able to convert only one molecule of ATP into cAMP, reducing the amount of cAMP produced. Not enough cAMP is generated and the cell undergoes signal termination. Phosphatases are activated to reduce the competition for the target protein of protein kinase A. Not enough molecules of protein kinase A are activated and the cellular response is dampened. Additional G protein-coupled ligands are expressed to compensate for the reduction in cAMP production.

Not enough molecules of protein kinase A are activated and the cellular response is dampened.

Which of the statements about the strands of a newly replicated DNA molecule is correct? Both strands contain some nucleotides from the original molecule. The base pairs are conserved, and new sugar-phosphate backbones are built up on them. One strand is new, and the other is from the original molecule. The sugar-phosphate chains are conserved, and new bases are inserted between them. Both strands are made up of newly assembled nucleotides.

One strand is new, and the other is from the original molecule.

Why are some mutations of Ras associated with cancer? Ras alters ion flow across the cell membrane. Ras activates the MAP kinase signal transduction pathway that regulates cell division. Ras binds to growth factor receptors. Ras is a type of second messenger.

Ras activates the MAP kinase signal transduction pathway that regulates cell division.

Refer to VS Map: Cellular Communities—Responding to Cellular Signals Tour. What happens if the conversion of GTP into GDP by the G protein is inhibited? The amplification reaction continues until ATP levels are too low. cAMP molecules are degraded into AMP. Polar ligands stop binding G protein-coupled receptors. Phosphatases dephosphorylate the target proteins of protein kinase A.

The amplification reaction continues until ATP levels are too low.

Why are single-stranded binding proteins necessary for DNA replication? None of the answer options is correct. They prevent the two parental strands from coming together again. They provide the energy necessary to separate the two strands of DNA. They direct the primase where to lay down the primer. They direct where replication will start.

They direct where replication will start.

What is the end-result of activating the MAP kinase pathway? a change in gene expression synthesis of second messenger moleculesion flow phosphorylation of multiple cytosolic proteins

a change in gene expression

Sea otters are adorable and also have 38 chromosomes in their somatic cells. If nondisjunction occurs in meiosis I of a male sea otter's chromosomes, the resulting four sperm cells will have the following chromosome numbers: a) 18, 18, 20, 20. b) 38, 38, 37, 39. c) 19, 19, 19, 19. d) 19, 19, 18, 20. e) 37, 37, 39, 39.

a) 18, 18, 20, 20.

Microtubules increase in length: a) All of these choices are correct. b) by lengthening outward from the centrosome. c) in cycles, following rapid depolymerization. d) by adding tubulin dimers to the ends. e) more quickly at one end than the other.

a) All of these choices are correct.

Which statement is true about G proteins? a) All of these choices are correct. b) Some G proteins are composed of three subunits. c) G proteins release GDP and bind GTP when associated with an activated receptor. d) G proteins can deactivate themselves by catalyzing the hydrolysis of bound GTP to produce GDP and inorganic phosphate. e) G proteins are a component of the signal-transduction pathways associate with a G protein-coupled receptor.

a) All of these choices are correct.

Microfilaments increase in length: a) more quickly at one end than the other. b) by assembling outward from the centrosome. c) in cycles of slower polymerization following rapid depolymerization. d) if free tubulin dimers are available. e) All of these choices are correct.

a) more quickly at one end than the other.

Which of these choices would block the activity of DNA polymerase? a) removal of the 5´ triphosphate from the nucleotides used by DNA polymerase b) removal of ribosomes from the DNA replication process c) removal of the 2´-OH from the last nucleotide of the daughter strand d) All of these choices would inhibit DNA polymerase activity. e) None of these choices are correct.

a) removal of the 5´ triphosphate from the nucleotides used by DNA polymerase

Refer to VS Map: Genetic Variation and Inheritance—Genetic Risk Factors and Breast Cancer Tour. Which events within the genome of a cell lineage can transform the cell type into cancer? Select all that apply. accumulation of successive mutations chromatin compaction DNA replication mutation in a DNA repair protein

accumulation of successive mutations mutation in a DNA repair protein

Refer to VS Map: Cellular Communities—Responding to Cellular Signals Tour. The ligand for a G protein-coupled receptor is added to cells, but they exhibit no cellular response. After some tests, you identify ATP levels are lower than normal but GTP levels are not lower than normal. Which process(es) are likely to be affected by this? Select all that apply. activation of adenylyl cyclase activation of G protein-coupled receptor activation of G proteinactivation of protein kinase A

activation of adenylyl cyclase activation of G proteinactivation of protein kinase A

Lengthening and shortening of microtubules can be affected by important anti-cancer drugs. As a result of treatment with one of these drugs, cell division is blocked and the cell cycle stalls (does not proceed to the next stage). What is happening to dividing cells treated with the anti-cancer drug? a) The cells are unable to divide the cytoplasm in cytokinesis and never complete division into two daughter cells. b) The cells cannot proceed through the spindle assembly checkpoint and stop dividing. c) All of the effects listed are possible results of Taxol treatment. d) The cells are unable to increase cyclin levels required to pass the G1 checkpoint. e) The cells are unable to replicate their chromosomes and stop dividing in S phase.

b) The cells cannot proceed through the spindle assembly checkpoint and stop dividing.

You strip off all proteins on the cell surface by using a protease (an enzyme that destroys proteins). Now, when you add a specific signaling molecule, the cell still responds. What is the most reasonable explanation of this? a) The signal can directly activate the second messenger system and does not need to activate the receptor. b) The receptor for this signal is inside the cell, and the signaling molecule is nonpolar and can diffuse into the cell. c) The receptor is a ligand-gated ion channel. d) The signaling molecule doesn't need a receptor.

b) The receptor for this signal is inside the cell, and the signaling molecule is nonpolar and can diffuse into the cell.

A number of mutations have been described in G proteins that have profound effects on their activity. For example, some mutations greatly increase the affinity of the G protein for GDP, making it very difficult for GDP to be exchanged for GTP. Other mutations prevent the hydrolysis of GTP to GDP. For each of the statements that describe a malfunction in cellular response, indicate the type of mutation that is responsible.A mutation causes an increase in kinase activity in the cytoplasm. Which type of mutation could be responsible for this increase in cytoplasmic kinase activity? a) Neither of the other answer options is correct. b) a Ras mutant that cannot hydrolyze GTP to GDP c) a Ras mutant with high GDP affinity

b) a Ras mutant that cannot hydrolyze GTP to GDP

Which of the processes is most important for passage through the G1 cell cycle checkpoint? a) expression of genes encoding cyclin-dependent kinases b) activation of cyclin-dependent kinases c) activation of DNA polymerase d) inhibition of cyclin proteins e) changes in membrane polarization

b) activation of cyclin-dependent kinases

In meiosis, recombination occurs: a) during both prophases I and II and involves exchange of chromosomes fragments between all four chromatids. b) during only prophase I and involves exchange between chromatids of homologous chromosomes. c) during only prophase II and involves exchange of chromosome fragments between sister chromatids. d) during both prophases I and II and involves exchange of chromosome fragments between sister chromatids.

b) during only prophase I and involves exchange between chromatids of homologous chromosomes.

What enzyme completes the covalent bond connecting the sugar phosphate backbone of adjacent Okazaki fragments together during replication? a) helicase. b) topoisomerase II. c) DNA ligase. d) DNA replicase. e) DNA polymerase.

c) DNA ligase.

What enzyme is capable of proofreading during DNA replication by replacing an incorrectly added nucleotide? a) topoisomerase II. b) helicase. c) None of the listed enzymes have this ability. d) DNA ligase. e) DNA replicase

c) None of the listed enzymes have this ability.

In a normal cell, tumor suppressors are responsible for: a) increasing the rate of cell division. b) signaling that DNA replication should begin. c) allowing the cell to correct replication errors. d) signaling that cells should pass a cell cycle checkpoint.

c) allowing the cell to correct replication errors.

A virus is surrounded by a protein coat known as a(n): protease. reverse transcriptase. surface protein. capsid. integrase.

capsid.

The concept of reverse transcription was at first very controversial because it: showed that viruses could function with an RNA genome suggested that RNA could sometimes function as an enzyme. contradicted the "central dogma" that the direction of expression of genetic information is always from DNA to RNA to protein. All of these choices are correct. implied that DNA could be translated into protein.

contradicted the "central dogma" that the direction of expression of genetic information is always from DNA to RNA to protein.

Refer to VS Map: Cellular Communities—Responding to Cellular Signals Tour. Which type of reaction is carried out by adenylyl cyclase? cyclization of ATP into cAMP phosphorylation of a protein target hydrolysis of ATP into ADP phosphorylation of GDP into GTP

cyclization of ATP into cAMP

The polymerase chain reaction (PCR) that has generated 128 copies of a region of amplified DNA has undergone how many cycles? a) 8 b) 6 c) 5 d) 7 e) 4

d) 7

The size of the wheat genome is about 22 times bigger than the human genome. Which of the following likely explains this difference? a) The wheat genome is polyploid. b) The wheat genome contains many repetitive DNA elements like transposons. c) The wheat genome likely contains many more genes. d) A and B e) A, B and C

d) A and B

When a ligand binds to a G protein-coupled receptor, which of the answer choices would you expect to happen before any of the others? a) The amount of cAMP in the cytoplasm increases. b) Protein kinase activity increases. c) Phosphodiesterase activity to break down cAMP increases. d) Adenylyl cyclase activity increases. e) None of the other answer options is correct.

d) Adenylyl cyclase activity increases.

Dynein motor proteins use the energy from ATP to: a) carry vesicles along a microtubule within a cell in a minus-to-plus direction. b) carry vesicles along a microfilament within a cell in a minus-to-plus direction. c) carry vesicles along a microfilament within a cell in a plus-to-minus direction. d) carry vesicles along a microtubule within a cell in a plus-to-minus direction. e) slide along microfilaments to contract muscle cells.

d) carry vesicles along a microtubule within a cell in a plus-to-minus direction.

Replication of linear DNA differs from circular DNA in that linear DNA: a) produces Okazaki fragments. b) produces a replication bubble. c) occurs at two replication forks. d) has multiple origins of replication. e) All of these choices are correct.

d) has multiple origins of replication.

Platelet-derived growth factor (PDGF) is a signaling molecule released by platelets at wound sites to cause nearby cells to undergo cell division, promoting healing. What type of signaling does this represent? a) endocrine signaling b) contact-dependent signaling c) autocrine signaling d) paracrine signaling e) All of these choices are correct.

d) paracrine signaling

Which of the following is most similar in the nucleotide sequence of DNA? a) homologous chromosomes b) the X and the Y chromosomes c) nonhomologous chromosomes d) sister chromatids e) non-sister chromatids

d) sister chromatids

During DNA replication in a cell, Primase synthesizes a primer that is complementary to the region in the sequence shown in bold: ​ 5´-CACAGCAGAACCCTACAACTCATG-3´ ​ What is the primer sequence? a) None of the answer options are primers synthesized by Primase. b) 5´-CUUGGGAUGUUG-3´ c) 5´-GTTGTAGGGTTC-3´ d) 5´-CTTGGGATGTTG-3´ e) 5´-GUUGUAGGGUUC-3´

e) 5´-GUUGUAGGGUUC-3´

Sexual reproduction results: a) in offspring that are not genetically identical. b) from combining genetic material from two gametes. c) in a new generation that is not genetically identical to its parents. d) in a new generation with the same number of chromosomes as each parent. e) All of these choices are correct.

e) All of these choices are correct.

You attach a yellow or blue fluorescent marker to nucleotides of DNA. Chromosomes composed of yellow nucleotides in both strands glow yellow under a microscope. When both strands are composed of blue nucleotides the DNA glows blue. When one strand is labeled yellow and the other blue the chromosomes glow green. You first grow yeast cells in the presence of "yellow" nucleotides until both DNA strands of all chromosomes glow yellow. Then, you allow cells with yellow labeled DNA undergo two rounds of replication in the presence of "blue" nucleotides so that newly synthesized strands are composed entirely of blue nucleotides. What color would you expect to see for sister chromatids following the second replication? a) All of these are possible outcomes for chromatids following two rounds of replication. b) Both chromatids will be green. c) One chromatid will be yellow, and the other will be blue. d) One chromatid will be yellow, and the other will be green. e) One chromatid will be blue, and the other will be green.

e) One chromatid will be blue, and the other will be green.

Insulin signaling through its receptor kinase enables virtually every cell in our body to transport glucose across the plasma membrane into the cytosol. In the next set of questions, select the appropriate event in the cellular response to insulin.Activated proteins in the nucleus that cause transcription (and eventually translation in the cytosol) of proteins needed for cell division is an example of: a) receptor activation. b) receptor binding. c) termination. d) signal transduction and amplification. e) response.

e) response.

Refer to VS Map: Cellular Communities—Responding to Cellular Signals Tour. A specific ligand is polar in nature. Where is the ligand-binding portion of the receptor most likely to be located? extracellular side of the cell membrane cytoplasm of the cell lumen (interior) of the endoplasmic reticulum cytoplasmic side of the cell membrane

extracellular side of the cell membrane

During DNA replication, the leading strand contains Okazaki fragments. false true

false

There is no correlation between genome size and complexity of an organism. false true

false

Refer to Animation: Nondisjunction. If nondisjunction occurs in the first meiotic division, how many of the four possible gametes produced from meiosis will have the wrong number of chromosomes? three four one two

four

What enzyme moves outward from the origin of replication and breaks hydrogen bonds between DNA nucleotides? DNA polymerase topoisomerase II RNA primase helicase

helicase

These enzymes play important roles in DNA replication: DNA polymerase, primase, ligase, helicase. In what order do they work during replication? ligase, helicase, DNA polymerase, primase helicase, primase, DNA polymerase, ligase DNA polymerase, helicase, primase, ligase primase, helicase, ligase, DNA polymerase DNA polymerase, primase, ligase, helicase

helicase, primase, DNA polymerase, ligase

A cell in which viral reproduction occurs is called a: host cell. daughter cell. sex cell. somatic cell. None of the other answer options is correct.

host cell

Cellular responses that result from receptor kinase activation tend to: involve changes in metabolism. involve ion channels. be short term. involve changes in gene expression.

involve changes in gene expression.

A eukaryotic chromosome has _____ origin(s) of replication, and a bacterial chromosome has ______ origin(s) of replication. many; many one; one one; many many; one

many; one

Refer to VS Map: Cellular Communities—Mitotic Cell Division Tour. Which stages of mitosis are correctly matched with the events that occur in the stage? Select all that apply. metaphase; chromosomes line up in the middle of the cell prometaphase; nuclear envelope reforms cytokinesis; a contractile ring of actin filaments forms at the cell equator anaphase; chromosomes start to condense telophase; nuclear envelope breaks down

metaphase; chromosomes line up in the middle of the cell cytokinesis; a contractile ring of actin filaments forms at the cell equator

Refer to Animation: Motor Proteins. Contraction of muscles is an example of how the motor protein _______ interacts with the cytoskeletal elements called _____________ to produce movement. myosin; dynein myosin; actin filaments actin; dynein kinesin; microtubules dynein; microtubules

myosin; actin filaments

Refer to Animation: Nondisjunction. In which type of nondisjunction could the two copies of a chromosome in a gamete be heterozygous? nondisjunction in the first meiotic division nondisjunction in the second meiotic division Nondisjunction in either meiotic division could produce gametes with two copies of a chromosome that are heterozygous.

nondisjunction in the first meiotic division

The point at which DNA synthesis is initiated is called the: start codon. origin of replication. replication fork. primase. primer.

origin of replication.

Many agricultural crops, like wheat, have more than two copies of the genome and are called: diploid. unicellular. polyploid. haploid. prokaryotic.

polyploid.

Which of the choices is not needed for DNA replication? DNA ribosomes nucleotides enzymes None of the answer options is correct.

ribosomes

Refer to VS Map: Cellular Communities—Mitotic Cell Division Tour. Which cell type(s) are not the result of mitosis? Select all that apply. epithelial cell sperm cell skin cell egg cell muscle cell

sperm cell egg cell

What feature of double-stranded DNA makes it necessary to have a leading strand and a lagging strand during replication? the hydrogen bonding between bases the base stacking of the basesthe negative charge on the sugar-phosphate backbone the antiparallel orientation of the strands

the antiparallel orientation of the strands