Chapter 11

An enzyme that catalyzes the addition of a phosphate group from ATP to another molecule is called a:

kinase.

Prokaryotic cells and eukaryotic cells reproduce by mitotic cell division. Regardless of the type of cell, all cells must _____ before they divide.

make a copy of their genetic information

Homologous chromosomes separate from each other in:

meiosis I.

The amount of _____ is fairly constant throughout the cell cycle, but the amount of _____ varies.

cyclin-dependent kinase/DNA

In meiosis, recombination occurs:

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

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

Which of the following is NOT true about the eukaryotic cell cycle?

Interphase is typically the shortest of the two stages of the cell cycle.

Which one of the following would MOST likely contribute to uncontrolled cell proliferation (i.e., cancer)?

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

Most of the significant changes in activities and functions that accompany passage through a cell cycle checkpoint are regulated by the:

activation of kinase enzymes.

CDKs are important in the regulation of the cell cycle. They carry out their function by:

adding phosphate groups to target proteins.

Proto-oncogenes:

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

Cancer-causing genes found in some viruses are called:

oncogenes.

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:

phosphorylation of specific proteins.

The CORRECT sequence of steps in the M phase of the cell cycle is:

prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis.

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

p53 is an example of a(n):

tumor suppressor.

Sister chromatids are BEST described as two DNA molecules that have:

virtually identical sequences of nucleotides.

How many copies of each gene are present in human skin cells at G2 of interphase?

4

The CORRECT sequence of steps in the eukaryotic cell cycle is:

G1 → S phase → G2 → mitosis → cytokinesis.

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

How would the loss of p53 activity affect a cell?

The G1/S checkpoint would not be functional. DNA damage could accumulate. CDK activity would not be appropriately regulated.

Which of the following statements is TRUE if a cell has a mutation in the p53 gene such that the p53 protein is no longer able to be phosphorylated?

The cell would proceed through the cell cycle even in the presence of DNA damage.

What would happen if a chromosome only connected to the mitotic spindle at one of its kinetochores?

The chromosome would not line up properly at metaphase. The sister chromatids would not separate. One of the daughter cells would have an extra copy of that chromosome.

Which of the following steps in prokaryotic binary fission is CORRECT?

The two replicated chromosomes remain attached to the plasma membrane. Cell wall material is laid down at the midpoint to separate the two daughter cells. All of these choices are correct. DNA is replicated bidirectionally from a single point on the circular chromosome. The cell continues to grow outward symmetrically, separating the two chromosomes.

Which one of the following is capable of phosphorylating key proteins involved in regulating the cell cycle?

cyclin-CDK complex

Sexual reproduction results:

in offspring that are not genetically identical. in a new generation with the same number of chromosomes as each parent. All of these choices are correct. in a new generation that is not genetically identical to its parents. from combining genetic material from two gametes.

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:

proto-oncogenes.

All of the following happen during mitosis EXCEPT:

synthesis of DNA.

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

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

12

Recall the experiments of Rous and colleagues. If he had found that filtered cancer cell extract could not cause cancer when injected into healthy animals, what could he have deduced?

All of these choices are correct.

What would happen to a cell if cyclin was always present in the cell? (Select all that apply.)

Cell cycle proteins would be always phosphorylated. The cell cycle would not stop at checkpoints. The cell would divide rapidly. Cyclin-dependent kinases would be always activated.

Which of the following statements is NOT true about sister chromatids?

They are formed when the prokaryotic circular chromosome attaches at the plasma membrane.

Which of the following is NOT true about gametes?

They are genetically identical to other gametes formed during meiosis.

During meiosis, two rounds of DNA synthesis are required to form four gametes from one parent cell.

false

The first oncogene to be discovered:

is a protein kinase that acts to promote cell division. is a gene that contributes to uncontrolled cell division or cancer. has a less-active normal counterpart called a proto-oncogene. was discovered in a Rous sarcoma virus that causes cancer.

Malignancies develop stepwise over time because:

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