Cell Bio Chapter 17

Adjacent hepatocytes are held together by:

cell junctions.

Spaces between adjacent endothelial cells allow red blood cells to leave the capillaries.

False

Detecting extracellular signals is important for survival but not for mating and reproduction.

False

Cells can be either signaling cells or targeting cells but not both.

False

Which of the following lists the events in the proper order?

cell communication, signal transduction, cellular response

A specific cellular response will depend on:

the extracellular signal, the receptor, and cell type.

Cells in a multicellular organism work not for their own survival but rather for the survival of the entire multicellular organism.

True

A cell that specializes in information processing at the organismal level does not undergo signal detection at the cellular level.

False

Which of the following modes of cell communication is the most “public”?

endocrine signaling

In which of the following modes of cell communication does the signal travel over a long distance but only to a specific target cell?

neuronal signaling

Which of the following is the most common type of extracellular signal?

chemical

The vast majority of chemical signals bind to transmembrane receptors in the cell membrane.

True

All cells in a multicellular organism respond to all extracellular signals.

False

The ability of a cell to either detect or ignore a signal is based on the presence or absence of a receptor for that signal.

True

A looped pathway where a downstream event inhibits an earlier upstream event is called:

negative feedback.

The binding of just a few chemical signals to a few receptors usually results in just a few activated intracellular proteins.

False

Which of the following amino acids are dual-specificity kinases NOT able to phosphorylate?

methionine

Phosphorylation of a given residue within a protein usually results in:

either activation or deactivation, depending on the protein being phosphorylated.

G-proteins are used as (choose the best answer):

molecular timers.

Some heterotrimeric G-proteins are tethered to the intracellular side of the cell membrane while others are not.

False

Which of the following type of protein stimulates the release of the spent GDP, thereby allowing the G-protein to bind a new GTP molecule to restart the cycle?

guanine nucleotide exchange factor (GEF)

Which of the following type of protein binds GTP-bound G-proteins to stimulate GTP hydrolysis faster than it would otherwise occur?

GTPase-activating protein (GAP)

Which of the following is a primary messenger?

an extracellular chemical signal

Second messengers can be rapidly produced by enzymes.

True