cell bio

The number of cells in an adult tissue or animal depends on cell proliferation. What else does it depend on? a) Apoptosis b) Necrosis

a) Apoptosis

Which of the following statements about the cell cycle is false? a) Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells b) A cell has more DNA during G2 than it did in G1. c) An unfavorable environment can cause cells to arrest in G1.

a) Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? a) The cell would enter M phase under conditions when normal cells would not. b) The cell would pass through M phase more slowly than normal cells c) The cell would be unable to enter G2. d) The cell would be unable to enter M phase.

a) The cell would enter M phase under conditions when normal cells would not.

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? a) The cells produced would get smaller and smaller b) Cells would get larger and larger c) The mitotic spindle could not assemble

a) The cells produced would get smaller and smaller

If cells that have started mitosis are treated with nocodazole, a drug that depolymerizes microtubules, what would you expect to happen? a) The cells would arrest in prometaphase. b) The cells would arrest in telophase. c) The cells would immediately enter anaphase, finish mitosis, and enter G1. d) The cells would arrest in metaphase.

a) The cells would arrest in prometaphase.

Which of the following events does not usually occur during interphase? a) The nuclear envelope breaks down b) The centrosomes are duplicated c) Cells grow in size d) DNA is replicated

a) The nuclear envelope breaks down

Imagine that you could microinject cytochrome c into the cytosol of both wild-type cells and cells that were lacking both Bax and Bak, which are apoptosis-promoting members of the Bcl2 family of proteins. The cell line that will undergo apoptosis a) both b) neither of the cell lines to undergo apoptosis c) cells that lack Bax and Bak only d) wild type only

a) both

The concentration of mitotic cyclin (M cyclin) ________________. a) falls toward the end of M phase as a result of ubiquitylation and degradation b) rises only during M phase c) is activated by phosphorylation d) is highest in G1 phase

a) falls toward the end of M phase as a result of ubiquitylation and degradation

BAX gene activation by p53 is in response to a) irreparable DNA damage b) DNA damage c) increase in cytochrome c

a) irreparable DNA damage

Which property of p53 enables it to prevent the development of cancer? a) p53 prevents the replication of cells with damaged DNA b) p53 is a transcription factor that causes production of proteins that stimulate the cell cycle c) p53 prevents cells from triggering apoptosis

a) p53 prevents the replication of cells with damaged DNA

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? a) The cell would be unable to enter M phase. b) The cell would enter M phase under conditions when normal cells would not. c) The cell would pass through M phase more slowly than normal cells d) The cell would be unable to enter G2

b) The cell would enter M phase under conditions when normal cells would not.

Progression through the cell cycle requires a cyclin to bind to a Cdk because _________. a) the cyclins are the molecules with the enzymatic activity in the complex. b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity. c) without cyclin binding, a cell-cycle checkpoint will be activated. d) cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle.

b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity.

P21, the protein activated by p53 in response to DNA damage is a a) cyclin inhibitor b) proapoptotic protein c) Cdk inhibitor

c) Cdk inhibitor

Which of the following statements most correctly describes meiosis? a) Meiosis involves four rounds of DNA replication followed by two successive cell divisions. b) Meiosis involves a single round of DNA replication followed by four successive cell divisions. c) Meiosis involves a single round of DNA replication followed by two successive cell divisions. d) Meiosis involves two rounds of DNA replication followed by a single cell division

c) Meiosis involves a single round of DNA replication followed by two successive cell divisions.

During the process of ______, 2 daughter cells will be created with identical DNA. a) Meiosis b) DNA replication c) Mitosis d) Protein synthesis

c) Mitosis

Which of the following statement is correct? a) DNA damage is due to low level of p53 b) The level of p53 in normal cell is high c) The level of p53 in normal cell is low

c) The level of p53 in normal cell is low

The cell is not allowed to pass the cell cycle restriction point if DNA damage is detected. Which protein is involved in detection of DNA damage and inhibition of the cycle at the restriction point? a) Cyclin D b) Bax c) p53 d) Caspase

c) p53

The extracellular matrix of connective tissue is made up of a) The extracellular matrix of connective tissue is made up of b) fibroblasts and ground substance c) protein fibers and ground substance d) lacunae and protein fibers

c) protein fibers and ground substance

Which of the following is not an example of a connective tissue? a) bone b) the jellylike interior of an eye c) the layer of photoreceptors in the eye d) cartilage

c) the layer of photoreceptors in the eye

The G1 DNA damage checkpoint ________________. a) causes cells to proceed through S phase more quickly. b) involves the degradation of p53. c) is activated by errors caused during DNA replication. d) involves the inhibition of cyclin-Cdk complexes by p21.

d) involves the inhibition of cyclin-Cdk complexes by p21.