Flashcards in Exam 2 Koh- Retina Biochem 1 Deck (69)
How is vision started?
Photon absorption by the visual pigments in cone and rods
Retinal circuit integrates ____ analog info of photoreceptors into a digital signal at the ______ cell level
What are the 2 laminar structures of the retina?
Outer retinal pigment epithelium (RPE) and inner neural retina
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
How thick are photoreceptors?
~200 micrometers thick
The photoreceptors transduce light into an _______ signal
Amacrine cells are ______ interneurons
How many amacrine cells are there?
How many morphological types of ganglion cells are there?
Mammals other than primates have what types of cones?
Only 2 types (L and S cones)
What is the function of photoreceptors?
Detect food source, mate, predator/prey, orientation
What are opsins?
Visual pigments, a vitamin A-based chromophore, a seven-transmembrane-helix apoprotein, prototypical G protein-coupled receptors
How are signals transduced?
Signal via heterotrimeric G proteins
How many opsins are in the animal kingdom?
What are opsins structurally similar to?
Bacteriorhodopsin and channelopsins
What are the 2 major groups of opsins?
R and C
Rhabdomeric photoreceptors _______ to light
What motif does r-opsin use for phototransduction?
Ciliary vertebrate rods and cones _________ to light
What motif does c-opsin use for phototransduction?
Rod phototransduction is good for understanding other sensory transduction in _____ and _____
Olfaction and taste
Where does rod phototransduction take place?
In the cell's ciliary outer segment
How many rhodopsins?
1 billion rhodopsins per ROS
Retinitis pigmentosa is caused by mutations in the gene for ______
What leads to autosomal dominant retinitis pigmentosa?
Improperly folded or constitutively activated protein
What leads to autosomal recessive retinitis pigmentosa?
Impaired activation or reduced opsin level
Supplementation with natural or synthetic retinoids may slow photoreceptor degeneration owing to _____ _____
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
When do cone photoreceptors disappear?
3 months of age