Exam 2 Koh- Retina Biochem 1 Flashcards Preview

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Flashcards in Exam 2 Koh- Retina Biochem 1 Deck (69)
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1

How is vision started?

Photon absorption by the visual pigments in cone and rods

2

Retinal circuit integrates ____ analog info of photoreceptors into a digital signal at the ______ cell level

Graded, ganglion

3

What are the 2 laminar structures of the retina?

Outer retinal pigment epithelium (RPE) and inner neural retina

4

What is the origination of the laminar structures?

Laminar structures arise from an invagination of the embryonic optic cup that folds an ectodermal layer into apex-to-apex contact with itself

5

How thick are photoreceptors?

~200 micrometers thick

6

The photoreceptors transduce light into an _______ signal

Electrical

7

Amacrine cells are ______ interneurons

Inhibitory

8

How many amacrine cells are there?

>50 types

9

How many morphological types of ganglion cells are there?

>10-15 types

10

Mammals other than primates have what types of cones?

Only 2 types (L and S cones)

11

What is the function of photoreceptors?

Detect food source, mate, predator/prey, orientation

12

What are opsins?

Visual pigments, a vitamin A-based chromophore, a seven-transmembrane-helix apoprotein, prototypical G protein-coupled receptors

13

How are signals transduced?

Signal via heterotrimeric G proteins

14

How many opsins are in the animal kingdom?

>1000

15

What are opsins structurally similar to?

Bacteriorhodopsin and channelopsins

16

What are the 2 major groups of opsins?

R and C

17

Rhabdomeric photoreceptors _______ to light

Depolarize

18

What motif does r-opsin use for phototransduction?

Phospholipase C

19

Ciliary vertebrate rods and cones _________ to light

Hyperpolarize

20

What motif does c-opsin use for phototransduction?

Cyclic-nucleotide

21

Rod phototransduction is good for understanding other sensory transduction in _____ and _____

Olfaction and taste

22

Where does rod phototransduction take place?

In the cell's ciliary outer segment

23

How many rhodopsins?

1 billion rhodopsins per ROS

24

Retinitis pigmentosa is caused by mutations in the gene for ______

Rhodopsin

25

What leads to autosomal dominant retinitis pigmentosa?

Improperly folded or constitutively activated protein

26

What leads to autosomal recessive retinitis pigmentosa?

Impaired activation or reduced opsin level

27

Supplementation with natural or synthetic retinoids may slow photoreceptor degeneration owing to _____ _____

Opsin mutations

28

What happens to mice with a knockout mutation in the rod opsin gene?

Fail to form rod OS and have no rod electroretinographic (ERG) response, but show a cone response early in life

29

When do cone photoreceptors disappear?

3 months of age

30

What light does rhodopsin absorb best?

Green, insensitive to red light