Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

The Visual System > Photopigments of Rods and Cones > Flashcards

Photopigments of Rods and Cones Flashcards

1
Q

Rods and cones contain special photopigments each containing what?

A

A protein: opsin and a chromophore.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a chromophore?

A

A light-sensitive molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the photopigment of rods?

A

rhodopsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the photopigment of cones?

A

color pigments or iodipsins or cone opsins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the opsin protein in rods called?

A

Scotopsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the opsin portion in cones called?

A

Photopsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What sets scotopsins and photopsin apart?

A

They have different amino acid composition and they absorb different wavelength of light.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Chromorphore is the same or different in rods and cones?

A

They are the same.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the chromophore composition?

A

an aldehyde of vitamin A (retinaldehyde)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

11-cis retinal isomer of retinal is what?

A

The chromophore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is rhodopsin?

A

Scotopsin plus 11-cis retinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the functions of the visual pigments?

A

They act as photoreceptors and they are required for vision.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What do the visual pigments detect?

A

Detection of shape, depth, and color.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The absorption of light energy by rhodopsin causes what?

A

a raid transformation fo 11-cis retinal to all trans retinal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What binds less avidly to opsin ?

A

Trans retinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does all trans retinal isomer cause?

A

Conformational changes in scotopsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What activates the transducin ( a G-Protein)?

A

The trans retinal isomer becomes free and moves laterally in the plasma membrane and then activates it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What occurs during the regeneration of rhodopsin?

A

All trans retinal is converted to 11-cis retinal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How is all trans retinal converted to 11-cis retinal?

A

by retinal isomerase

20
Q

Regenerated 11 cis retinal automatically recombines with scotopsin to form what?

A

Rhodopsin.

21
Q

When rhodopsin is activated it is what?

A

Decomposing rhodopsin

22
Q

When rhodopsin is deactivated it is what?

A

regenerated rhodopsin

23
Q

Where is vitamin A present?

A

In the cytoplasm of the rods and cones as well as in retinal pigment epithelial cells.

24
Q

What does vitamin A convert to?

A

11-cis retinal as needed.

25
Q

What occurs to Vitamin A for storage?

A

excess retinal is converted to retinol (vit A)

26
Q

What is night blindness (nyctalopia)?

A

the inability to see in relatively low light.

27
Q

What is a major cause of night blindness?

A

Vitamin A deficiency

28
Q

What is vitamin A deficiency?

A

Less retinal is formed than needed

29
Q

At night or with low light the retinal levels are what?

A

inadequate for vision in a subject that has night blindness.

30
Q

The dark is referred to what type of state?

A

unexcited state.

31
Q

The unexcited state Na+ conductance into outer segment of rods is what?

A

Greater than that of a typical sensory cells.

32
Q

What does the cyclic guanosine monophosphate regulate?

A

The transmembrane conductance of sodium in photoreceptor cells.

33
Q

In the dark what occurs to the cytoplasmic levels of cGMP?

A

They increase

34
Q

What occurs when cGMP levels increase?

A

The cGMP regulated channels become activated and increase Na+ influx.

35
Q

The membrane potential in an unexcited state in a low light environment is what?

A

More positive

36
Q

The membrane potential of that in any other sensory cells in an unexcited state is what?

A

More negative.

37
Q

The excitation of rods by light results in what?

A

hyper polarization not depolarization

38
Q

excitation in other sensory receptors are usually caused by?

A

depolarization

39
Q

In bright light the activation of rhodopsin causes what?

A

stimulation of the G protein called transducin

40
Q

The activation of transducin leads to what?

A

The stimulation of phosphodiesterase

41
Q

What does phosphodiesterase do in Rod hyper polarization in light?

A

hydrolyzes cGMP to 5’GMP

42
Q

The activation of photopigments in cones is similar to what?

A

Rods

43
Q

What does the activation in cones require?

A

More photons for the same response in as rods.

44
Q

Cones are 30-300 fold less what then rods?

A

Less sensitive to light than rods.

45
Q

The extent in amplification in con excitation cascade is what?

A

much less than in rods.

The Visual System (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions