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