EVERYDAY SCIENCE

SCIENCE

CELL BIOLOGY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The cholesterol associated with membranes
A
is attached to proteins and extends into the environment surrounding the cell
B
helps stabilize the membrane at body temperature
C
is an abnormality resulting from a diet high in cholesterol
D
both a and c
Explanation: 

Detailed explanation-1: -Cholesterol acts as a bidirectional regulator of membrane fluidity because at high temperatures, it stabilizes the membrane and raises its melting point, whereas at low temperatures it intercalates between the phospholipids and prevents them from clustering together and stiffening.

Detailed explanation-2: -Cholesterol is also a key determinant of membrane fluidity: at high temperatures, cholesterol acts to stabilize the cell membrane and increase its melting point; while at low temperatures, it inserts into phospholipids and prevents them from interfering with each other to avoid aggregation [39].

Detailed explanation-3: -Cholesterol influences the fluidity of the membrane, and it does so in a bidirectional manner; at high temperatures it decreases fluidity and at low temperatures it increases fluidity. At high temperatures, cholesterol’s flat, rigid structure limits phospholipid movement.

Detailed explanation-4: -The role of cholesterol in bilayer and monolayer lipid membranes has been of great interest. On the biophysical front, cholesterol significantly increases the order of the lipid packing, lowers the membrane permeability, and maintains membrane fluidity by forming liquid-ordered–phase lipid rafts.

Detailed explanation-5: -Acting as essential building blocks of the plasma membranes, cholesterol plays pivotal roles in maintaining the structural integrity and regulating the fluidity of cell membranes [17–20], therefore contributing to the homeodynamics of various membrane proteins on the cell surface.

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