Choose a common response used to propagate a signal within a cell.

(A) Dephosphorylation of a target

(B) triggering of a second messenger

(C) enzyme cleavage

B

The variation in responses from different cells to the same ligand is due to differences in ________.

(A) signal amplification

(B) protein expression

(C) receptor types

B

The general name for an enzyme that transfers phosphate groups from ATP to a protein is:

(A) protease

(B) phosphate

(C) phosphorylase

(D) protein kinase
(E) ATPase

D

Chemical signal pathways:

(A). are absent in bacteria, but are plentiful in yeast.

(B) involve the release of hormones into the blood.

(C). often involve the binding of signal molecules to a protein on the surface of a target cell.

(D). operate in animals, but not in plants

D

Adenylyl cyclase has the opposite effect of which of the following?

(A). phosphodiesterase

(B). protein phosphatase

(C). GTPase

(D). protein kinase

(E). phosphorylase

A

Which of the following proteins is directly activated by a G protein?
(A). phospholipase A2

(B). protein kinase G

(C). adenylate cyclase

(D). Tyrone kinase

(E). calmodulin

C

Which of the following enzymes catalyzes synthesis of diacylglycerol and inositol triphosphate?
(A). dopamine β-hydroxylase

(B). phenylethanolamine N-methyl transferase

(C) phospholipase C

(D). phosphoprotein phosphatase

(E). cyclooxygenase

C

What chemical messenger diffuses to neighboring cells to exert an effect?
(A). autocrine

(B). paracine

(C). hormone

(D). neurotransmitter

(E). neurohormone

B

Which of the following is true of the mating signal transduction pathway in yeast?

(A). The signal reception, transduction, and response occur in the nucleus.

(B). Mating type a secretes a signal called a factor.

(C). Scientists think the pathway evolved long after multicellular creatures appeared on Earth.

(D). The pathway carries an electrical signal between mating cell types.\

(E). The molecular details of the pathway in yeast and in animals are very different.

B

Which of the following most likely would be an immediate result of growth factor binding to its receptor?
(A). protein phosphatase activity

(B). phosphorylase activity

(C). protein kinase activity

(D). adenylyl cyclase activity

(E). GTPase activity

C

Second messenger molecules directly:

(A). increase intracellular calcium contrition

(B). change regulation of gene activity

(C). change enzyme activity

(D). all of the answers are correct

(E). change the regulation of ion channels

D

____ are one the of small hydrophobic ligands used in cellular signaling.

(A). large ions

(B) steroid hormones

(C). peptides

B

Peptides are one type of ________ used in cellular signaling.

(A). hydrophilic ions

(B). water-soluble ligands

(C). small hydrophobic ligands

B

Which of the following enzymes catalyzes synthesis of cAMP?

(A). adenylate cyclase

(B). tyrosine β-hydroxylase

(C). phospholipase A2

(D). phosphodiesterase

(E). tyrosine kinase

A

Which of the following is the most common second messenger in the human body?

(A). cGMP

(B). calcium

(C). IP3

(D). DAG

(E). cAMP

E

What molecule, whose synthesis is catalyzed by phospholipase C, triggers the release of calcium from the endoplasmic reticulum?
(A). diacylglycerol

(B). inositol biphosphate

(C). cGMP

(D). inositol triphosphate

(E). phosphatidylinositol biphosphate

D

Paracrine signaling
(A). has been found in plants but not animals.

(B). occurs only in paracrine yeast cells.

(C). involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid.

(D). requires nerve cells to release a neurotransmitter into the synapse.

(E). involves mating factors attaching to target cells and causing production of new paracrine cells.

C

________ secrete mating factors in preparation for sharing genetic material with another of their species.

(A). yeast

(B). bacteria

(C). fungi

A

The activation of receptor tyrosine kinases is characterized by:
(A). a phosphorylation cascade.

(B). dimerization and phosphorylation.

(C). GTP hydrolysis

(D). channel protein change shape

(E). IP3 binding.

B

The phosphorylation of a target is used to ________ a signal within a cell.

(A). initiate

(B). respond to

(C). propagate

C

Cells use protein molecules called receptors to receive signals, and the two types of receptors are ________ and cell-surface receptors.

(A). internal

(B). external

(C). gap junction

A

After a ligand binds to a cell-surface receptor, a series of ________ steps occurs that integrates the events eventually leading to a change in the cellular environment.

(A). signaling stream

(B). signaling cascade

(C). enzymatic cascade

B

B

The binding of lipophilic messengers, such as steroid hormones, to their receptors triggers
(A). protein kinase activation

(B). adenylyl cyclase activation

(C). cyclic nucleotide formation

(D). gene transcription

(E). G protein inhibition

D

Signal transduction pathways that influence gene expression do so by ________.

(A). regulating RNA transcription

(B). degrading proteins

(C). influencing DNA copy number

A

In ________ signaling, a cell targets itself.

(A). paracrine

(B). autocrine

(C). endocrine

B

________ are small molecules that diffuse between cells directly connected by gap junctions.

(A). intracellular mediators

(B). nerve impulses

(C). synaptic signals

A

T-cells that incorrectly respond to “self proteins” are targeted for ________ to prevent damage to the organism.

(A). necrosis

(B). reprogramming

(C). apoptosis

C

When adenylyl cyclase is activated,
(A). calcium ions are released from intracellular stores.

(B). cAMP is formed

(C). protein kinases are metabolized.

(D). steroids are produced

(E). cAMP is broken down

B

Cyclic AMP activates

(A). protein kinase A

(B). a G protein

(C). hormone receptors

(D). protein hormones

(E). adenylyl cyclase

A

In the yeast signal transduction pathway, after both types of mating cells have released the mating factors and the factors have bound to specific receptors on the correct cells,
(A). binding induces changes in the cells that lead to cell fusion

(B). the cell membranes fall apart, releasing the mating factors that lead to new yeast cells.

(C). one cell nucleus binds the mating factors and produces a new nucleus in the opposite cell.

(D). a growth factor is secreted that stimulates mitosis in both cells.

(E). the cells then produce the a factor and the α factor.

A