Video Transcript
Which of the following correctly
describes the effect of temperature on the fluidity of cell membranes? (A) With increased temperature, the
fluidity of the membrane decreases. (B) With increased temperature, the
fluidity of the membrane increases. (C) Changes in temperature have no
effect on the fluidity of the membrane.
First, let’s look at this term in
the question, fluidity of the cell membrane. Membrane fluidity is affected by
the properties of the phospholipids that make up the majority of the cell
membrane. When the phospholipids are
organized tightly, they don’t move around much and we say that the membrane is less
fluid. When they’re less tightly packed,
the phospholipids can move around more and the membrane is said to be more
fluid.
At low temperatures, molecules like
phospholipids generally move around less and more slowly. This forms a denser structure. At higher temperatures, more heat
energy is transferred to the phospholipids, which increases their kinetic energy and
causes them to move around more. This causes the phospholipids to
spread out and move around more, making the membrane more fluid. So the correct answer is option
(B). With increased temperature, the
fluidity of the membrane increases.
