Quiz 9

In a diploid individual, one chromosome carries A and B genes, and the homologous chromosome carries different forms (alleles) of these same genes, a and b. If there is a single crossover between these two genes involving non-sister chromatids during metaphase I of meiosis, the resulting four gametes are: AB, ab, AB, ab. AB, Ab, aB, ab. Ab, Ab, aB, aB. AaBb, AaBb, AaBb, AaBb. AB, AB, ab, ab.

AB, Ab, aB, ab.

Processes that regulate cell division in mammals include: production of cyclin proteins that activate CDK enzymes. different cyclins and CDKs acting at different stages of the cell cycle to promote cell division. All of these choices are correct. rapid degradation of cyclins after CDK activation. activated cyclin-CDK complexes triggering cell cycle events.

All of these choices are correct.

Studies of rapidly dividing embryonic animal cells revealed: that the production of cyclin proteins is followed by activation of CDK enzymes. a cyclic activation of protein kinases in sync with the cell cycle. All of these choices are correct. a cyclic production of certain proteins in sync with the cell cycle. that inhibition of protein production blocks mitosis.

All of these choices are correct.

The M cyclin-CDK complex: All of these choices are correct. controls the cell cycle during the M phase. triggers phosphorylation of certain nuclear proteins, resulting in breakdown of the nuclear envelope during prophase. initiates many events of mitosis. phosphorylates proteins that promote formation of the mitotic spindle.

All of these choices are correct.

The first oncogene to be discovered: All of these choices are correct. is a gene that contributes to uncontrolled cell division or cancer. was discovered in a Rous sarcoma virus that causes cancer. has a less-active normal counterpart called a proto-oncogene. is a protein kinase that acts to promote cell division.

All of these choices are correct.

Tumor suppressors oppose oncogenes by: blocking the action of an oncogene. All of these choices are correct. repairing mutations. slowing cell division. instructing defective cells to die.

All of these choices are correct.

Which of the following is NOT a hallmark of malignant cancer? Metastasis, which allows invasion of local tissues. Cell division in the absence of growth signals. All of these choices are hallmarks of cancer. Resistance to signals that slow cell division or promote death. Ability to stimulate growth of blood vessels to provide nutrients to the rapidly growing tumor.

All of these choices are hallmarks of cancer.

Which major checkpoint delays the cell cycle when DNA replication is incomplete? G1, G2, and the M checkpoints G1 checkpoint None of the checkpoints delays the cell cycle when DNA replication is incomplete. G2 checkpoint M checkpoint

G2 checkpoint

Paramecium is a single-cell eukaryotic organism that can reproduce by mitotic cell division. Prior to the M phase of the cell cycle, which of the following must occur? The cell must replicate its chromosomes. The cell must first be fertilized. The nuclear envelope must disintegrate. The nucleus must divide. Sister chromatids must be separated.

The cell must replicate its chromosomes.

Which of the following is NOT true regarding CDKs? They function to control the cell cycle. They bind to cyclin. The levels of CDK change with the cell cycle. They function as a kinase.

The levels of CDK change with the cell cycle.

What happens to CDKs in the absence of cyclins? They are degraded. They become phosphorylated. They are inactive and become phosphorylated. They are inactive.

They are inactive.

How do new cyclin proteins appear in the cytoplasm? They are made through protein synthesis. All of these choices are correct. They are recycled. They are imported from outside the cell.

They are made through protein synthesis.

How do CDKs promote cell division? They bind to DNA. They phosphorylate other proteins. They regulate the activity of cyclin. They cause cyclin levels to increase and decrease. They change the ability of microtubules to polymerize.

They phosphorylate other proteins.

Which one of the following would MOST likely contribute to uncontrolled cell proliferation (i.e., cancer)? a mutant kinetochore protein that causes reduced microtubule attachment a mutant DNA replication mechanism causing extra chromosome copies a mutant enzyme needed for microtubule synthesis/polymerization a mutant cyclin that cannot bind to its normal CDK binding partner a mutant CDK that was active in the absence of its cyclin binding partner

a mutant CDK that was active in the absence of its cyclin binding partner

What is a cyclin? a kinase a protein that activates kinases a protein that activates kinases and a protein whose levels change with the cell cycle a protein whose levels change with the cell cycle

a protein that activates kinases and a protein whose levels change with the cell cycle

What type of protein is being activated by the G1/S cyclin-CDK complex to promote the expression of histone proteins? a polymerase a synthase a helicase a transcription factor

a transcription factor

Most of the significant changes in activities and functions that accompany passage through a cell cycle checkpoint are regulated by the: activation of DNA polymerase. inhibition of cyclin proteins. activation of kinase enzymes. activation of microtubules. changes in membrane polarization.

activation of kinase enzymes.

The development of cancer requires both the _____ of an oncogene and the _____ of a tumor suppressor. inhibition; inhibition inhibition; activation activation; inhibition activation; activation

activation; inhibition

CDKs are important in the regulation of the cell cycle. They carry out their function by: degrading cyclin proteins. removing phosphate groups from target proteins. adding phosphate groups to target proteins. preventing the progression of a cell from one stage of the cell cycle to the next.

adding phosphate groups to target proteins.

Proto-oncogenes: None of the answer options is correct. can be mutated by cigarette smoke to become triggers for cancer. are mutated forms of genes involved in cell division that are hyperactive. encode for abnormal growth factors, cell surface receptors, or members of a signal transduction pathway.

can be mutated by cigarette smoke to become triggers for cancer.

The two strands in a molecule of DNA are: diploid. exact copies of each other. sister chromatids. homologous. complementary.

complementary

Which one of the following is capable of phosphorylating key proteins involved in regulating the cell cycle? p53 protein CDK cyclin phosphatase cyclin-CDK complex

cyclin-CDK complex

The division of the cell's cytoplasm in a eukaryotic cell is known as: cytokinesis. both cytokinesis and mitosis.. mitosis. cell fission.

cytokinesis.

Malignancies develop stepwise over time because: cells keep leaving the benign tumor and are destroyed in lymph nodes. it takes multiple mutations of multiple genes to allow cancer cells to develop. it takes time for a benign tumor to be able to dissolve through its encapsulation before it can invade neighboring tissues. benign tumor cells divide slowly and in a stepwise pattern. All of these choices are correct.

it takes multiple mutations of multiple genes to allow cancer cells to develop.

The FoxP2 gene is thought to be involved in language in humans. At prophase I, how many copies of the FoxP2 gene are present in a cell? Keep in mind that humans are diploid. two copies, one on each homologous chromosome four copies, one on each sister chromatid in a pair of homologous chromosomes eight copies, one on each strand of each chromatid per homologous pair eight copies, one on each sister chromatid in a pair of homologous chromosomes

four copies, one on each sister chromatid in a pair of homologous chromosomes

Paired chromosomes in a cell that share the same set of genes are called: bivalent chromosomes sister chromatids non-sister chromatids homologous chromosomes

homologous chromosomes

An enzyme that catalyzes the addition of a phosphate group from ATP to another molecule is called a: phosphorylase. phosphatase. kinase. cyclase.

kinase.

A malignant cancer differs from a benign cancer in that: benign cancers are lethal and malignant ones are not. malignant cancers are caused by viruses and benign cancers are not. malignant cancers invade surrounding tissue and benign cancers do not. malignant cancers are lethal and benign cancers are not.

malignant cancers invade surrounding tissue and benign cancers do not

Sister chromatids are separated during: mitosis. meiosis II. meiosis I and mitosis. meiosis II and mitosis. meiosis I.

meiosis II and mitosis.

In which phase of mitosis do chromosomes line up at the middle of the cell? metaphase prophase telophase anaphase

metaphase

Cancer-causing genes found in some viruses are called: oncogenes. tumor suppressor genes. proto-oncogenes. viral genes.

oncogenes.

Synapsis is best described as the: pairing of homologous chromosomes in prophase I. alignment of non-sister chromatids at the metaphase plate. exchange of genetic information between non-sister chromatids. exchange of genetic information between sister chromatids.

pairing of homologous chromosomes in prophase I.

Many of the specific functions that are triggered when a cell passes one of the cell cycle checkpoints result from activation of enzymes and other proteins. A common mechanism for this activation is: signal transduction. polymerization of tubulin. phosphorylation of specific proteins. ATP synthesis.

phosphorylation of specific proteins.

Colchicine is a drug that is used in plant breeding to create polyploids. It blocks the assembly of microtubules. If dividing cells are treated with colchicine, at what stage of mitosis would you predict the arrest would occur? prophase G1 of interphase metaphase late anaphase telophase

prophase

Taxol is an anti-cancer drug that prevents uncontrolled cell proliferation by stabilizing microtubules, which causes arrest of the cell cycle. If dividing cells are treated with Taxol, at what stage of the cell cycle would you predict the arrest would occur? prophase telophase anaphase metaphase G1 of interphase

prophase

Many normal genes that have important functions in cells sometimes acquire mutations that cause the products of these genes to have negative effects, including the development of cancer. These genes are called: oncogenes. viral genes. proto-oncogenes. tumor suppressor genes.

proto-oncogenes.

Several years ago, a man noticed a small mole on his wrist. Years later, the mole grew in size and the man was diagnosed as having metastatic melanoma. This was likely the result of: None of the other answer options is correctcancers arise spontaneously, independent of mutations. a single mutation affecting one proto-oncogene in a cell. a single mutation inactivating a tumor suppressor gene. several mutations affecting proto-oncogenes and/or tumor suppressor genes.

several mutations affecting proto-oncogenes and/or tumor suppressor genes.

The epithelial cells in the skin of an animal have 24 chromosomes. How many chromosomes are present in the gametes of this animal? 12 24 6 48

12

Consider a diploid organism with a haploid complement of four chromosomes. At prophase I, how many total chromosomes will be present in a cell? 8, four pairs of homologous chromosomes 4, one complete set of chromosomes 12, four pairs of homologous chromosomes and their haploid complement 16, four pairs of homologous chromosomes and two sister chromatids per chromosome

8, four pairs of homologous chromosomes

A graduate student is planning an experiment to evaluate the expression of PDGF-related genes in her cell population of interest. As a control, she hopes to confirm the expression of genes that are present in all dividing cells. For her controls, she should evaluate the expression of: Notch. G proteins. PDGF. laminin. CDKs.

CDKs.

Predict what would happen if crossing over between homologous chromosomes occurred as part of mitosis. There would be no effect because sister chromatids separate in anaphase. Daughter cells would not be genetically identical. Daughter cells could contain two copies of the same allele. Daughter cells would not be genetically identical, and they could contain two copies of the same allele.

Daughter cells would not be genetically identical, and they could contain two copies of the same allele.

Look carefully at the image of the human karyotype shown in Figure 11.3. What is the significance of the small differences between homologous chromosomes? Chromosomes may not be completely replicated during S phase. The differences are a result of the way the material was prepared. Some of this person's DNA is mutated, possibly causing disease. Each homologous chromosome in a pair is from a different parent.

Each homologous chromosome in a pair is from a different parent.

Which of the following statements regarding tumor suppressors is TRUE? None of the other answer options is correct. Tumor suppressors include PDGF and cyclins. Mutations affecting tumor suppressors can contribute to the development of cancers. Tumor suppressors promote cell division. Tumor suppressors act synergistically with proto-oncogenes.

Mutations affecting tumor suppressors can contribute to the development of cancers.

What would happen if crossing over occurred between sister chromatids? Nothing would happen because sister chromatids are genetically identical or nearly identical. Genetic diversity would decrease due to the loss of gene combinations. Genetic diversity would increase due to the addition of gene combinations. Gene rearrangement would lead to changes in gene expression.

Nothing would happen because sister chromatids are genetically identical or nearly identical.

When in the cell cycle would you find sister chromatids? G1 S and G2 G2 S

S and G2

How does meiosis generate genetic diversity? random alignment at metaphase I crossing over both crossing over and random alignment at metaphase I synapsis

both crossing over and random alignment at metaphase

Which of the following would be MOST likely to lead to the development of cancer? the activation of an oncogene and the inactivation of a tumor suppressor gene the activation of a tumor suppressor gene the activation of a proto-oncogene the activation of an oncogene and the activation of a tumor suppressor gene

the activation of an oncogene and the inactivation of a tumor suppressor gene

A homologous chromosome pair is best described as two chromosomes that have: different alleles of the same genes arranged in a different order. the same genes in the same order but possibly with different alleles of some of the genes. the same alleles of the same genes in the same order. identical sequences of nucleotides. the same genes possibly arranged in a different order with potentially different alleles of some of the genes.

the same genes in the same order but possibly with different alleles of some of the genes.

. Why are the X and Y chromosomes NOT considered homologous? they do not carry the same set of genes they do not carry the same set of genes, and mammalian males carry two very different sex chromosomes mammalian males carry two very different chromosomes they come from different parents

they do not carry the same set of genes, and mammalian males carry two very different sex chromosomes

What is the function of the centromere? to attach the DNA to the plasma membrane to attach the chromosome to the spindle to attach the sister chromatids to each other to organize the microtubules to form a spindle

to attach the sister chromatids to each other