2nd messengers I Flashcards Preview

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Flashcards in 2nd messengers I Deck (40)
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1
Q

4 classes of cellular signaling molecules

A

hormones
local mediators
neurotransmitters
growth factos

2
Q

growth factos

A

signaling molecules that regulate cell proliferation and differentiation

3
Q

hormones

A

have regulatory effects on specific organs or tissues at a site distrant from hormone secretion

4
Q

how do hydrophilic hormones work

A

bind to plasma membrane receptor

either generate intracellular second messenger or activate receptor enzymatic acitivty

5
Q

what do hydrophilic hormones generally result in

A

changes in activity of meabolic enzymes (typically rapid)

6
Q

what are lipophilic hormones often derived from

A

cholesterol

7
Q

function of lipophlic hormones

A

pass through plasma membrane and bind receptors in nucleus or ceyptoplasm

8
Q

what does binding of lipophilic hormones result in

A

altered transcription (slower response)

9
Q

how do water soluble hormones mainly function

A

binding to specific receptors

10
Q

GDP bound form is waht

A

inactive

11
Q

GTP bound form is what

A

active

12
Q

GTPase

A

hydrolyze GTP to GDP and can turn themselves off

13
Q

what happens when the G protein gets acitived

A

dissociation of the alph asubunit from the beta-gamma dimer

14
Q

G-proteins frequenctly activate proteins that generate what

A

intracellular second messengers

15
Q

Gs generally does what

A

stimulates activity of enzymes

16
Q

Gi generally does what

A

inhibit activity of certain enzymes

17
Q

Gq generally does what

A

stimulates activity of certain enzymes

18
Q

2 imporant enzymes that are directly modulated by bindign to activated G proteins

A

adenylate cyclase, phospholipase C

19
Q

what does adenylate cyclase catalyze the formation of

A

cAMP and PPi

20
Q

hydrolysis of PPi by pyrophosphatease acitvies drives what

A

reaction in direction of cAMP formation

21
Q

is the adenylate cyclase reaction reversible or irreveresble

A

irreversible

22
Q

what is the principle target for cAMP

A

protein serine/threonine kinase (PKA)

23
Q

how is cAMP signaling shu toff

A

degrated by phosphodiesterases

interstrinc GTPase

24
Q

how does glucagon affect cAMP and PKA

A

elevate cAMP

activate PKA

25
Q

glycogen

A

stoarge form of glucose

26
Q

where aer the main deposits of glycogen

A

liver and skeletal msucle

27
Q

function of glycogen in the liver

A

buffer blood glucose during times of fasting

28
Q

function of epinephrine

A

glycogenolysis in muscle
fat hydrolysis in adipose
incrase rate and strength of HR

29
Q

function of glucagon

A

glycogenolysis in liver

fat hydrolysis in adipose tissue

30
Q

function of arginine vasopression

A

water reabsorption in kidney

31
Q

function of phospholipiase C

A

hydrolyzes phosphatidlyinosital 4,5 bisphosphate to generate IP3 and DAG

32
Q

IP3 charactersitics

A

water soluble

diffuses into cytosole

33
Q

DAG characteristics

A

lipophilic, remains membrane associated

34
Q

function of IP3

A

binds to receptors that open Ca++ channels.

35
Q

affects of Ca++

A

help activate protein kinase C

bind calmodule

36
Q

function of DAG

A

help active PKC

37
Q

how do you turn of signaling from phosphatidylinositol 4,5-bisphosphate

A

receptor down regulation/interanlization and degration

protein phosphateases reverse action of PKC

38
Q

how do you get rid of Ca++

A

pump out of cytosal

39
Q

how do you stop IP3

A

dephosphorylated by specific phosphatase, converting it to a derviative that does not open the Ca++ channel

40
Q

how do you stop DAG

A

phosphorylated, or hydrolyzed