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8 Cards in this Set
- Front
- Back
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what is the function of retinoic acid?
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it is a ligand for nuclear hormone receptors that modulate txn (it is not converted to retinal or retinol in the body)
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retinol is toxic in high doses, but beta carotene is not, why?
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Cleavage of beta carotene to retinoids in insufficient in the body.
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vitamin A is stored in the liver as...
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retinyl palmitate
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vitamin A deficiency can lead to what?
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night blindness, and in the very young who consume no vit A->xeropthalmia and keratomalacia
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rhodopsin is a GPCR with 11-cis retinal covalently linked to what amino acid at what transmembrane helix?
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to lysine at 7th helix
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What distinguishes rhodopsin as well as the three color opsin proteins from each other?
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They are each connected to 11 cis retinal by different amino acids thus affecting color sensation.
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what is the name of the G protein activated by the opsins and what does it activate?
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transducin activates a PDE in the disk membrane that cleaves cGMP
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How are cGMP levels re-raised after the PDE cleaves them?
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Ca2+ continues to pump out of the hyperpolarized cell. Once Ca2+ is low enough guanylyl cyclase is activated and PDE is inactivated.
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