Problem:

Please help me with these study questions on my review! Thank u

Question 1: Signal transduction "cross talk" implies:

a. that once a second messenger is produced, it can directly activate cascade pathways usually activated by other second messengers

b. that second messengers produced by one cascade pathway can alter a different one at a number of points as a consequence of the latter's sensitivety to the normal cascade changes/products of the former

c. That if more than one second messenger is produced simultaneously in the cell as a resulton hormone-receptor binding, the combined effects of both pathways will be cancelled out to preserve cellular homeostasis

d. that if many second messengers are produced simultaneously in the cell, the cell will become "homeostatically deranged" and self destruct

e. none of the above

Question 2: Phospholipase C is:

a. An enzyme that forms cyclic AMP from ATP

b. is inhibited by drinking alcohol

c. is an enzyme that uses phospholipids as a substrate

d. an enzyme that phosphorylates proteins

e. a and c only

Question 3: A chemical messenger that can cross the cell membrane into the cytoplasm

a. bind with G proteins

b. bing with cytoplasmic receptors

c. form a chemical messenger/receptor complex that acts as a transcription factor for specific genes

d. B and C

e. none of the above

Question 4: The term "turnover number" refers to:

a. the rate at which receptor proteins are synthesized

c. the rate at which protein kinase enzymes are broken down

c. how fast m-rNA molecules leave the nucleus to travel to the ribosomes

d. how fast signal transduction systems produce a physiological responce

e. NONE of the choices above are correct

Question 5: The enzymes that are responsible for "post transcriptional modification" are called

a. exons

b. Introns

c. snRNPs

d. STATs

e. None of the above

Question 6: In order for calmodulin kinase to be activated

a. it must be "switched on" by a regulatory molecule

b. calmodulin must bind non-covalently to the enzyme

c. it must be activated by the JAK-STAT pathway

d. A and B only

e. C only

Question 7: what two essential properties of signal transduction pathways are important for them to function properly?

a. Amplification

b. secretion

c. control

d. multiplication

e. A and B

f. A and C

g. C and D

h. B and D

Question 8: which hormone (chemical messenger) is not synthesized from cholesterol?

a. aldosterone

b. thyroid hormone

c. estradiol

d. cortisol

e. progesterone

Question 9: The JAK-STAT signal transduction pathway:

a. uses cyclic- AMP as its second messenger

b. Stimulates gene transcription through activation of a transcription factor

c. has a receptor that is capable of autophosphorylation

d. phosphorylates proteins that are capable of activating certain genes

e. all but A

Question 10: Steroid hormones exert their cellular actions by:

a. combining with cell membrane receptors and initiating signal transduction cascades with second messenger production

b. entering the cell and directly activating specific protein kinases

c. combining with cytoplasmic receptors and initiating gene transcription

d. combining with cytoplasmic receptors and phosphorylating proteins

e. none of the above

Question 11: What is a G protein?

a. it is a receptor molecule

b. it is an allosteric membrane protein

c. it is an intermediary molecule between a membrane bound receptor molecule and a membrane bound enzme in a signal transduction pathway

d. it is a second messenger

e. B and C are both correct

Question 12: Calmodulin is:

a. an allosteric activator

b. a protein

c. an activator of calmodulin kinase

d. an activator of protein kinase C

e. all but D

Please suggest correct answer.