nov.12 pt4

Question 1

what happens when light hits outer segment of photoreceptor?

Answer 1

change in RMP

Question 2

RMP of photoreceptor cell

Answer 2

minus forty mV

Question 3

light causes __ in membrane of photoreceptor cells

Answer 3

HYPERPOLARIZATION

Question 4

example of change in RMP in photoreceptor cells

Answer 4

minus 40mV to minus 65mV

Question 5

cGMP gated channels of photoreceptor cells are ____ when its dark

Answer 5

open

Question 6

advantage of metabtropic receptors in photoreceptors

Answer 6

amplification

Question 7

three steps of PHOTOTRANSDUCTION

Answer 7

1. activation of visual pigment ie photoreceptor by light 2. activated photopigment triggers biochemical signalling pathway leading ot reduction of cGMP 3. closure of cGMP gated channels and hyperpolarization

Question 8

cGMP gated channels are

Answer 8

nonselective cation channels

Question 9

reversal potential of the cGMP gated channels

Answer 9

0

Question 10

photopigment consists of

Answer 10

opsin and vitamin A aldehyde AKA 11-cis retinal

Question 11

opsin is this type of protein

Answer 11

GPCR

Question 12

opsin is covalently linked to

Answer 12

lysine

Question 13

opsin is light sensitive when

Answer 13

attached to 11-cis retinal

Question 14

light has this effect on rhodopsin

Answer 14

conformational change to 11-trans retinal, triggering conformation change in opsin

Question 15

what happens to retinal after photoisomerization

Answer 15

dissociate from opsin, transported out of photoreceptor cells, taken up into epithelial cells, converted back to 11-cis retinal, and transported back

Question 16

when GTP binds alpha subunit of G protein

Answer 16

alpha dissocaites from beta gamma, g alpha then activates PDE, hydrolyzing cGMP to GMP

Question 17

all events leading to cGMP hydrolsis occurs in

Answer 17

membranes of disks

Question 18

result of PDE activation

Answer 18

reduce cyto conc of cGMP, cGMP-gated channels close