MCAT BIO

5' cap

a methylated guanine nucleotide added to the 5' endof eukaryotic mRNA. The cap is necessary to initiate translation of mRNA

A band

The band of the sarcomere that extends the full length of the thick filament. The A band includes regions of thick and thin filament overlap, as well as a region of thick filament only. A bands alternate with I bands to give skeletal and cardiac muscle a striated apperance. The A band does not shorten during muscle contraction.

Absolute refractory period

A period of time following an action potential during which no additional action potential can be evoked regardless of the level of stimulation. (usually because Na+ channel closed whle K+ efflux)

Accessory glands

The three glands in the male reproductive system that reproduce semen: the seminal vesicles, the prostate

Accessory organs