Seidler's Lecture Flashcards
Where to find rhodopsin
photoreceptor in rods
Structure of rhodopsin
seven transmembrane
protein opsin linked to 11-cis-retinal
Resting State of rhodopsin
Schiff base if protonated
Maximum absorption for rhodopsin
500 nm which means Schiff base if protonated
Schiff base linkage
retinal linked to lysine 296
Signal transduction
light comes in –> rhodopsin –> transducin –> cGMP phosphodiesterase –> allow Na+ in to induce signal
Rods
rhodopsin for night vision
high sensitivity and low spatial resolution
most active in dim light
Cones
for color detection
Three opsins
low sensitivity and high spatial resolution
Three opsins
red, green, blue
Rod Cell Retinoid Cycle
light induced change from 11-cis to all trans
release of all trans from opsin
reduction from trans-retinal to trans RETINOL
exportation of all trans retinol
Cone cycle
Processing proteins at extremely high rates
1 to 1 relationship between cone and ganglion cell
Vitamin A deficiencies
Night blindness, Xerophthalmia, keratinization of epithelium in Gi, respiratory and genitourinary tract, skin becomes dry and scaly
What controls the body’s vitamin A?
beta-carotene
Night blindness
vitmamin A deficiency
hurts the rods- so can’t see in the dark
Xerophthalmia
vitamin A deficiency
abnormal dryness of conjunctiva and cornea of the eye
can’t produce tears
