Biochemistry Of The Eye

Question 1

What is the relationship in terms of ratio of rods and cones to ganglion cells?

Answer 1

Rods: a cluster: 1 ganglion cell

Cones: 1 cone: 1 rod

Question 2

Which cells are for night vision?

Answer 2

Rods

Question 3

What cells are used for color detection?

Answer 3

Cones

Question 4

Where are mitochondria of rods and cones located?

Answer 4

Inner segment

Question 5

In the dark, explain what happens with sodium and the polarization of the cells?

Answer 5

Na+ channels are open and the cell is depolarized

Question 6

In the light, explain what happens with sodium and the polarization of the cells?

Answer 6

Na+ channels are closed and the cell is hyperpolarized

Question 7

What is the prosthetic group found on rhodopsin which responds to photons?

Answer 7

11-CIS-retinal

Question 8

What is the surface membrane Na channel gated with?

Answer 8

CGMP (so in darkness this is present and opens the channels)

Question 9

The photoreceptor protein has how many transmembrane portions?

Answer 9

7

Question 10

What receptor does rhodopsin resemble?

Answer 10

Beta- 2- adrenergic receptor

Question 11

What wavelength does rhodopsin optimally absorb light?

Answer 11

500 nm

Question 12

What amino acid is covalently linked to 11-CIS retinal?

Answer 12

Lysine (by a Schiff-base linkage which is reversible)

Question 13

Color blindness is ____ linked

Answer 13

X (red Opsin and green opsin)

Question 14

What are the 2 macular carotenoids?

Answer 14

• Lutein

- Zeaxanthin

Question 15

What enzymes contribute to retinitis pigmentosum?

Answer 15

LRAT and RPE65

Question 16

Which cells are the output for the retina?

Answer 16

Ganglion cells