Question

11-5 A bacterium is suddenly expelled from a warm human intestine into the cold world

outside. Which of the following adjustments might the bacterium make to maintain the
same level of membrane fluidity?
(a) Produce lipids with hydrocarbon tails that are longer and have fewer double
bonds.
(b) Produce lipids with hydrocarbon tails that are shorter and have more double
bonds.
(c) Decrease the amount of cholesterol in the membrane.
(d) Decrease the amount of glycolipids in the membrane.

Answer 1

To maintain membrane fluidity in a colder environment, a bacterium would produce lipids with hydrocarbon tails that are shorter and have more double bonds.

Step-by-step explanation:

When a bacterium is expelled from a warm human intestine into a colder external environment, it must adjust its membrane composition to maintain the same level of membrane fluidity. In response to colder temperatures, the bacterium would likely produce lipids with hydrocarbon tails that are shorter and have more double bonds, option (b). Unsaturated fatty acids, with their 'kinks' created by double bonds, elbow adjacent phospholipid molecules away, providing space that maintains fluidity at lower temperatures. By contrast, saturated fats with straight tails would pack tightly together and cause the membrane to become more rigid.