β-Carotene is the precursor of vitamin A1.
Oxidation at C-15 converts retinol to the aldehyde, retinal, and further oxidation produces retinoic acid, a hormone that regulates gene expression. 

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#Id: 9162

#Unit 11. Evolution and Behavior

A recessive allele (a) that causes a genetic disease has a frequency (q) of 0.01. If the population mates randomly (F = 0), the frequency of individuals affected by the disease (aa) will be q = 0.01 = 0.0001.

However, if F = 0.25 expected frequency of the aa is .0026.

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#Id: 2096

#Unit 8. Inheritance Biology

EFFECTS OF CHROMOSOME DUPLICATIONS- Bar phenotype in Drosophila

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#Id: 5194

#Unit 7. System Physiology – Animal

Factor X can be activated by either of two systems: Intrinsic system Extrinsic system

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#Id: 3412

#Unit 3. Fundamental Processes

SOS response in E. coli:

When DNA is extensively damaged (such as by UV light), DNA replication is halted and the number of single-strand gaps in the DNA increases.

RecA protein binds to this damaged, single-stranded DNA, activating the protein’s co-protease activity.

While bound to DNA, the RecA protein facilitates cleavage and inactivation of the LexA repressor. When the repressor is inactivated, the SOS genes, including RecA, are induced;

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#Id: 4018

#Unit 7. System Physiology – Animal

When the potential reaches a threshold voltage of about −40 millivolts, the L-type calcium channels become “activated,” causing the action potential