The cell membrane is a phospholipid bilayer that forms a barrier around cells. The fluidity of the membrane must be maintained within a certain range for proper cell functioning. Several factors influence membrane fluidity, including the length of fatty acid tails, temperature, cholesterol content, and degree of saturation. Longer fatty acid tails, lower temperatures, more cholesterol, and more saturated fatty acids decrease fluidity by increasing interactions between phospholipid molecules.

1. MEMBRANE FLUIDITY
DEEPIKA JALAL

2. • All cells are surrounded by a cell membrane
that forms a barrier between the cell and its
surroundings.
• This membrane is often referred to as the
phospholipid bilayer.
• The name, a phospholipid bilayer is made up of
two layers of lipids.
• The fluidity of this membrane must be
maintained within a certain range for the cell to
function properly.
• There are a number of factors that help
influence membrane fluidity.

4. •The length of the fatty acid tail
• The length of the fatty acid tail impacts the
fluidity of the membrane.
• This is because the intermolecular interactions
between the phospholipid tails add rigidity to
the membrane.
• As a result, the longer the phospholipid tails,
the more interactions between the tails are
possible and the less fluid the membrane will
be.

5. •Temperature
• As temperature increases, so does phospholipid
bilayer fluidity.
• At lower temperatures, phospholipids in the
bilayer do not have as much kinetic energy and
they cluster together more closely, increasing
intermolecular interactions and decreasing
membrane fluidity.
• At high temperatures the opposite process
occurs, phospholipids have enough kinetic
energy to overcome the intermolecular forces
holding the membrane together, which
increases membrane fluidity.

6. Cholesterol content of the
bilayer
• Cholesterol has a somewhat more complicated
relationship with membrane fluidity. it is a buffer
that helps keep membrane fluidity from getting too
high or too low at high and low temperatures.
• At low temperatures, phospholipids tend to cluster
together, but steroids in the phospholipid bilayer
fill in between the phospholipids, disrupting their
intermolecular interactions and increasing fluidity.
• At high temperatures, the phospholipids are
further apart. In this case, cholesterol in the
membrane has the opposite effect and pulls
phospholipids together, increasing intermolecular
forces and decreasing fluidity.

7. • The degree of saturation of fatty
acids tails
• Phospholipid tails can be saturated or
unsaturated.
• The terms saturated and unsaturated refer to
whether or not double bonds are present
between the carbons in the fatty acid tails.
• Saturated tails have no double bonds and as a
result have straight, unkinked tails.
• Unsaturated tails have double bonds and, as a
result, have crooked, kinked tails.

9. • Saturated fatty acids tails are arranged in a way that
maximizes interactions between the tails.
• These interactions decrease bilayer fluidity.
• Unsaturated fatty acids, on the other hand, have
more distance between the tails and thus fewer
intermolecular interactions and more membrane
fluidity.

10. SUMMARY