Deck 10: Signaling

Question 1

Hormones bind to _____ with _____ affinity.

A) ligands; low
B) agonists; high
C) antagonists; low
D) G proteins; low
E) receptors; high

Answer 1

receptors; high

Question 2

When a receptor loses its ability to transmit a signal following continuous exposure to a ligand, the receptor is said to be _____.

A) saturated
B) desensitized
C) transduced
D) specific
E) none of the above

Answer 2

desensitized

Question 3

Which of the following can be a hormone?

A) amino acid derivatives
B) steroids
C) polypeptides
D) eicosanoids
E) all of the above

Answer 3

all of the above

Question 4

A sample of cells with a total receptor concentration of 50 $\mu$ M was incubated with a ligand concentration of 100 $\mu$ M. Following the incubation period, the concentration of unbound receptors was determined to be 15 $\mu$ M. What is the K_d for the receptor-ligand interaction?

A) 28 $\mu$ M
B) 43 $\mu$ M
C) 143 $\mu$ M
D) 217 $\mu$ M
E) 333 $\mu$ M

Question 5

Which of the following is a ligand of the $\beta$ ₂-adrenergic receptor?

A) tyrosine
B) serotonin
C) norepinephrine
D) caffeine
E) adenosine

Question 6

Activity of the Ras protein is analogous to the _____ in terms of its ability to bind GTP.

A) G protein $\alpha$ subunit
B) G protein $\beta$ subunit
C) G protein $\gamma$ subunit
D) calmodulin
E) all of the above

Question 7

The ability for some receptor tyrosine kinases to ultimately activate phospholipase C is an example of _____.

A) antagonism
B) desensitization
C) autophosphorylation
D) poor receptor-ligand specificity
E) cross-talk

Question 8

Which of the following hormones is able to cross biological membranes and thus the receptor is found inside the cell, not on the cell surface?

A) insulin
B) glucagon
C) cortisol
D) epinephrine
E) platelet derived growth factor

Question 9

The complex formed between a lipid hormone and its receptor binds to _____ which are specific DNA sequences.

A) transcription factors
B) nuclear localization sequences
C) DNA-binding domains
D) hormone response elements
E) none of the above

Question 10

The eicosanoids are derived from the membrane fatty acid _____.

A) stearic acid
B) linoleic acid
C) $\alpha$ -linolenic acid
D) arachidonic acid
E) docosahexaenoic acid (DHA)

Question 11

Which of the following is an inhibitor of cyclooxygenase?

A) acetaminophen
B) aspirin
C) eicosanoic acid
D) thromboxane
E) progesterone

Question 12

Which of the following can be regulated by eicosanoids?

A) blood pressure
B) blood coagulation
C) inflammation
D) fever
E) all of the above

Question 13

In order for cAMP to ___ protein kinase A, cAMP binds to the ___ subunits.

Question 14

The action of a ___ results in the hydrolysis of cAMP, thus decreasing the signal from ___.

Question 15

Interaction of the Ras protein with ___ results in activation by ___

Question 16

The _____ signaling pathway undergoes autophosphorylation, resulting in kinase activation.