Chromosome compaction involving progressive chromosome looping:

During prophase, condensin II binds DNA and extrudes large loops

In prometaphase, condensin I forms additional loops nested within the loops formed by condensin II

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#Id: 9307

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A single activated rhodopsin protein activates 

~13 transducin molecules in the few seconds before the covalent bond between the opsin protein and all-trans-retinal is spontaneously cleaved

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#Id: 9308

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RPE65 is the enzyme in the pigment epithelial cells of the retina that catalyzes the isomerization of the intermediate esterified all-trans retinol to 11-cis-retinol.

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#Id: 9309

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Autosomal recessive mutations in the RPE65 gene are a frequent cause of blindness in children.

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#Id: 9310

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In the dark, 

membrane potential of a rod cell is about −30 mV (Depolarized state)

Rod cells release neurotransmitters (glutamate) constantly

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#Id: 9311

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#Id: 9312

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Depolarized state of a resting rod cell is due to the presence of a large number of open nonselective ion channels that admit both Na+ & Ca²+ into the cell