1.4(dii) - The vertebrate eye

Question 1

What is the retina responsible for?

Answer 1

Detecting light

Question 2

What are the two types of photoreceptors in the retina?

Answer 2

1.Rods
2.Cones

Question 3

What do rods do?

Answer 3

Function in dim light but don’t allow colour perception

Question 4

What do cones do?

Answer 4

Responsible for colour perception but require bright light to function

Question 5

In animal rod cells, what is retinal?

Answer 5

A prosthetic group in the protein opsin

Question 6

What is the retinal-opsin complex called

Answer 6

Rhodopsin

Question 7

What happens when retinal absorbs a photon of light?

Answer 7

Rhodopsin changes conformation to photoexcited rhodopsin

Question 8

Photoexcited rhodopsin triggers what?

Answer 8

A cascade of proteins that will amplify the photon signal and generate a nerve impulse

Question 9

Photoexcited rhodopsin (after triggering cascade) activates what?

Answer 9

A G-protein (transducin) which activates an enzyme called phosphodiesterase