BIO-333 Quiz 3 Answers

Which of the following statements about apoptosis is true

Apoptosis is promoted by the release of cytochrome c into the cytosol from mitochondria

In which phase of the cell cycle do cells check to determine whether DNA is fully and correctly replicated?

At the end of G2

The cyclin that compromises the S-Cdk complex is

Cyclin A

The cyclin that comprises the G1-Cdk complex is

Cyclin D

A cell can crawl through a tissue because of the transmembrane ______________ proteins that can bind to fibronectin outside of the cell.

Integrin

How does S-Cdk help guarantee that replication occurs only once during each cell cycle?

It phosphorylates the Cdc6 protein, marking it for destruction

which of the following statements is false?

Proteoglycans are a major component of compact connective tissues but are relatively unimportant in watery tissues such as the jelly like substance in the interior of the eye

Which of the following statements is false?

The activating phosphatase (Cdc25) removes all phosphates from mitotic Cdk so that M-Cdk will be active

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only?

The cells would get smaller and smaller

Ras is a GTP-binding protein that is often defective in cancer cells. A common mutation found in cancer cells causes Ras to behave as though it were bound to GTP all the time, which will cause cells to divide inappropriately. From this description, the normal Ras gene is

a proto-oncogene

Which type of junction involves a connection to the actin cytoskeleton?

adherens junctions

Proteoglycans in the extracellular matrix of animal tissues

allow cartilage to resist compression

A totipotent cell

can give rise to all the tissues and cell types in the body

Apoptosis differs from necrosis in that necrosis

causes cells to swell and burst, whereas apoptotic cells shrink and condense.

Which of the following molecules is not found in plants?

collagen

Which of the following statements about collagen is false?

collagen synthase organizes the mature collagen molecules into ordered collagen fibrils

MPF activity was discovered when cytoplasm from a Xenopus M-phase cell was injected into Xenopus oocytes, inducing the oocytes to form a mitotic spindle. In a control experiment, Xenopus interphase cytoplasm was injected into oocytes and shown not to induce the formation of a mitotic spindle. Which of the following statements is not a legitimate conclusion from the control experiment?

components of an interphase nucleus are insufficient to cause mitotic spindle formation

The concentration of mitotic cyclin (M cyclin)

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

The retinoblastoma (Rb) protein blocks cells from entering the cell cycle by

inhibiting cyclin transcription

Which of the following statements about integrins is false?

integrins use adaptor proteins to interact with microtubule cytoskeleton

The G1 DNA checkpoint

involves the inhibition of cyclin-Cdk complexes by p21

When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of ________.

proliferating precursor cells

Progression through the cell cycle requires cyclin to bind to Cdk because

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

Which of the following statements about plant cell walls is true?

the microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall

Which of the following statements about cancer is false?

A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell