In C. elegans

When sperm fuses with the egg cell membrane, polyspermy is prevented by the rapid synthesis of chitin by the newly fertilized egg.

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#Unit 2. Cellular Organization

Overlapping gene are the same sequence of DNA encodes two nonhomologous proteins because it uses more than one reading frame.

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#Unit 7. System Physiology – Animal

Cushing syndrome Chronic excess of glucocorticoids (hypersecretion of ACTH from a pituitary adenoma)

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#Unit 7. System Physiology – Animal

L-type calcium channels become inactivated (i.e., they close) within about 100 to 150 milliseconds after opening

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#Unit 3. Fundamental Processes

Once bound to Pol II, Ptefb phosphorylates the serine residue at position 2 of the CTD repeats. That phosphorylation event correlates with elongation. In addition, P-TEFb phosphorylates and thereby activates another protein, called SPT5, itself an elongation factor. Finally, TAT-SF1, yet another elongation factor, is recruited by P-TEFb. Thus, P-TEFb stimulates elongation in three separate ways.

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#Unit 4. Cell Communication and Cell Signaling

There are about 90 million rod cells in the human retina, and each contains about 4x107 molecules of rhodopsin that are very densely packed in the membrane disks.