Hrenchir - Biochem Test 2

Front 1

What is a primary or signal messanger?

Back 1

messanger that binds to extracellular receptors.

drugs, hormones, light, etc.

Front 2

What is signal transduction?

Back 2

transfer of signal from outside of cell to inside of cell

Front 3

What is a cell surface receptor/G-protein coupled receptor(GPCR) or 7-Transmembrane receptor?

Back 3

Protein embedded in the cell membrane. The N-terminus has a binding site for signal messangers.

Front 4

What is a G protein?

Back 4

a heterotrimeric (alpha, beta, gama) complex that binds guanyl nucleotides.

Front 5

What is downstream effector activation? ex. adenylate cyclase

Back 5

an effector is a molecule that binds to a protein and activates the release of a second messanger

Front 6

What is a second messanger?

Back 6

molecule that transmits the signal inside the cell to tarter molecules in the cytosol/nucleus

Front 7

what is a kinase?

Back 7

enzyme that phosphorylates specific target molecules

Front 8

T or F . . . 7-TM receptors change conformation when signal binds

Back 8

T

Front 9

What do second messengers trigger?

Back 9

Protein phosphorylation

Front 10

what do protein kinases phosphorylate?

Back 10

inactive proteins inorder to activate them

Front 11

T/F . . . Kinases are involved in turning the signal off?

Back 11

T

Front 12

How is a signal turned off?

Back 12

1) dissociation of ligand from receptor
2) phosphorylation of the receptor

Front 13

What does a G-Protein bind to when resting?

Back 13

GDP

Front 14

What happens to the G-protein when a ligand binds to a receptor?

Back 14

the G-protein changes conformation so that the GDP is released and a GTP binds.

Front 15

What happens to the alpha subunit once a G-protien changes conformation and releases the GDT and picks up a GTP?

Back 15

the alpha subunit dissociates from the beta/gama subunit and then the alpha subunit binds to adenylyl cyclase activating it to produce cAMP from ATP.

Front 16

List the steps of the Epinephrine signal transduction pathway.

Back 16

1) ephinephrine is released and binds to B-andrenergic receptors

2) binding stimulates G-prot. causing the G-prot conformation change which releases GDP and binds GTP. Alpha subunit then dissociates w/ the GTP to produce cAMP from ATP.

3) cAMP binds to protein kinase A which then activates phosphorylase kinase and gycogen phosphorylase which converts glycogen to glucose 6-phosphate into glucose

4) glucose is then transported outside of teh cell and into the bloodstream where it is used as a fuel by other cells to induce a "fight or flight" response.

Front 17

how many molecules of glucose can be produced from 20 molecules of cAMP?

Back 17

10,000 molecules of glucose

Front 18

What terminates the epinephrine cascade?

Back 18

The G-protein(alpha) has intrinsic GTPase activity which hydrolyzes bound GTP to GDP and Pi.

Front 19

How long does the ATPase activity of the G-alpha take to terminate signaling?

Back 19

slow, seconds to minutes. This means Gprot can activate downstream components. After hydrolysis the GDP Alpha subunit reassociates with the G(beta/gama) subunits.

Front 20

List out the steps of the ANGIOTENSION signaling pathway.

Back 20

1) Angiotensin binds to the angiotensin receptor.

2) Stimulates G-protein

3) G(alpha) subunit activates phospholipase C which converts PIP2 to DAG and IP3

4) IP3 binds to and opens the Ca2+ channels on the endoplasmic reticulum --> Ca2+ is released.
4) Intracellular Ca2+ the binds to calmodulin which then binds to and activates PKC

4) PKC causes smooth muscle contractions and glycogen breakdown.

5) DAG actives PKC which phosphorylates other cellular proteins.

Front 21

What does EGF stand for?

Back 21

Epidermal Growth Factor

Front 22

List out the steps of RAS activation.

Back 22

1) EGF binds to EGF receptor

2) cross phosphorylation occurs

3) phosphorylated Tyr is bound by Grb-2

4) Grb-2 binds SOS

5) SIS binds Ras

6) Ras activated and releases GDP and binds GTP

7) Ras binds Raf

Front 23

What does Raf do?

Back 23

Raf acts as a protein kinase to change the activity of other proteins and control cell growth and differentiation

Front 24

List the three ways in which cancer chemotherapy can kill rapidly growing cells.

Back 24

1) antimetabolites

2) severely damaging DNA by alkylating agents

3) inhibiting receptor binding by use of anticytokines and antihormones

Front 25

What is the relationship between ABL and BCR? What does gleevec do to solve this problem?

Back 25

ABL is a gene coding for a particular protien kinase. When this gene is inserted into the BCR gene it leads to defects in a growth signal cascade because it is not properly regulated and becomes over active.

gleevec trets myelogenous leukemia by inhibiting BCR-ABL kinase activity

Front 26

How does cholera effect the body? Generally speaking and pathway wise.

Back 26

Invection by Vibrio cholerae which produces a toxin called choleragen that triggers massive secretion of electrolytes and fluids.

One B subunit of toxin binds to gut cell gangliosides and the other A subunit enters the cell. The A subunit selfstabilizes the Galpha protein in the GTP bound (ON) state.

The A unit produces unending quantities of protein kinase A.

This inturn opens a chloride ion channel and turns off the phosphorylation a Na/H exchanger. This leads to excessive loss of NaCl and water into the intestine. Loss of water and electrolytes follow.

Front 27

What is Pertussis/whooping cough caused by. How does it work.

Back 27

Caused by infection by Bordetella pertussis.

Bordetella pertussis produces a toxin that modifies adenylyl cyclase, closes Ca2+ ion channels and opens K+ ion channels. The cyclase is jammed in the OFF position.

Severe and debilitating cough reults.