cell cycle

Protein

Which of the following component molecules of the plasma membrane is most important in the reception phase of cell signaling?

Through opening and closing of ligand-gated ion channels

In cell signaling, how is the flow of specific ions regulated?

A protein on the cytoplasmic side of a membrane that becomes activated by a receptor protein

What is a G-protein?

Protein kinase

Which of the following can activate a protein by transferring a phosphate group to it?

Relay the message from the inside of the membrane throughout the cytoplasm

Many signal transduction pathways use second messengers to:

Testosterone, a steroid hormone

Which of the following signal molecules pass through the plasma membrane and bind to intracellular receptors that move into the nucleus and function as transcription factors to regulate gene expression?

Cytokinesis

If this did not occur, daughter cells would have two complete sets of chromosomes

Synthesis

The genetic material of the cell replicates to prepare for cell division.

Gap 1

The cell is carrying out its typical functions and is not engaged in producing molecules necessary for division.

Synthesis

Failure of this stage to occur prior to mitosis would result in daughter cells without sufficient DNA.

The cell-cycle control system operates independently of the growth factors.

Which of the following statements regarding the cell cycle control system is false?

Telophase

Cytokinesis begins during this final stage of mitosis.

Metaphase

Sister chromatids align in the center of the cell.

Anaphase

Sister chromatids begin to separate.

Interphase

The genetic material of the cell replicates to prepare for cell division.

Prometaphase

What stage of mitosis is represented in this figure?

Glycogen breakdown is observed only when epinephrine is administered to interact, living cells, yet epinephrine does not enter the cell.

Earl Sutherland received the Nobel Prize for his discovery of cAMP as a second messenger. Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Fus3 is required for the signal transduction pathway leading to shmoo formation.

A model, like the diagram, helps scientists visualize and form testable hypotheses. What hypothesis was being tested with the Fus3 strain?

To show normal shmoo formation under the experimental conditions.

In addition to testing shmoo formation in the two mutant strains of yeast, the scientists also shmoo formation in wild-type (nonmutant) yeast. What is the purpose of including wild-type yeast cells in the experiment?

The Fus3 strain should not form shmoos, and the cells should not have a red zone in their walls.

One of their hypotheses was that Fus3 kinase is required for the signal transduction pathway leading to shmoo formation. If this hypothesis is correct, what result should be observed in the Fus3 strain?

The only formin molecules that get phosphorylated and thus activated are those near the G protein-coupled receptor that binds mating factor.

Fus3 kinase and formin proteins are generally distributed evenly throughout a yeast cell. Based on the model in the diagram, why does the shmoo projection emerge on the same side of the cell that bound the mating factor?

No shmoo would form in response to a mating factor

What do you predict would happen if the yeast had a mutation that prevented the G protein from binding GTP?

The therapy will target cells that are metabolically active and prevent mitotic spindle formation.

Cancer therapies target a number of aspects of the cell cycle. Which approach would you predict would be most promising for chemo-therapy?

Species B cells are in the G0 phase.

What is the best explanation for the data associated with Species B cells?

Species A

Which species spent the greatest percentage of their cell cycle time in G2?

Nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cell's nucleus.

Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence?