Answer:
Cholesterol is exclusively found in
animals. and is the most abundant animal sterol. Cholesterol was
first isolated from bile and the word literally means "solid
alcohol from bile".
Cholesterol is widely distributed in
the cells and is a major component of cell membranes and
phospholipid layer where it carries out many functions:
- As a Structural component of plasma
membranes, cholesterol is an important determinant of membrane
permeability.
- It makes the membrane less
permeable to very small water soluble molecules that would
otherwise freely cross the membrane.
- It immobilizes the outer surface of
the membrane, reducing it's fluidity.
- As cholesterol is poor conductor of
heat and electricity, it acts as an insulating cover.
- Cholesterol strengthens the
phospholipid bilayer
- It helps regulate activity of
certain membrane proteins