Isomerization

Question 0

Outer segment of receptors composed of…

Answer 0

…lamellae with embedded PHOTOPIGMENT molecules that react to light,

made of OPSIN and RETINAL

Question 1

isomerization

Answer 1

converting light into a neural signal

Question 2

Opsin

Answer 2

long protein chain (150 X as large as Retinal)

Question 3

Retinal

Answer 3

short lipid segment

synthesized from Vitamin A

Question 4

Why Opsin changes color from reddish-purple to pale yellow (“bleached”)

Answer 4

11-Cis Retinal absorbs photon of light,

changes shape (straightens, now called All-trans Retinal)

and detaches from Opsin

Question 5

Second Messengers

Answer 5

activated by retinal absorption of photons of light, changing shape, and detaching from Opsin

in the Receptor

lead to ion gates closing, MODIFYING GRADED RELEASE OF NT

Question 6

Each rod has…

Answer 6

~10 mil photopigment molecules, called Rhodopsin

Question 7

Cones have less…

Answer 7

photopigment, their own variants

Question 8

Photopigment Regeneration

Answer 8

• recombination of Retinal & Opsin
• using enzymes from Pigment Epithelium
• Requires time

Question 9

Light Adapted

Answer 9

• e.g. Hard to see indoors at first after bright sunlight but as regenerate, sensitivity restored

Question 10

Dark Adapted

Answer 10

• e.g. Hard to see just after turn off lights, but soon, as more regenerate, sensitivity increased