Question

A hypothetical "microbullet" shot through a phospholipids bilayer will pass the component in which order?

1) tail >>> tail >>> head >>> head
2) head >>> tail >>> tail >>> head
3) head >>> tail >>> head >>> tail
4) head >>> head >>> tail >>> tail
5) tail >>> head >>> tail >>> head

Answer 1

A hypothetical "microbullet" passing through a phospholipid bilayer would encounter the hydrophilic head, the hydrophobic tails, another set of hydrophobic tails, and finally another hydrophilic head, in that order: head >>> tail >>> tail >>> head.

Step-by-step explanation:

The question pertains to the arrangement of the phospholipid bilayer in cellular membranes. A phospholipid has a hydrophilic head that is attracted to water, and a hydrophobic tail composed of fatty acids that repels water. When phospholipids form a bilayer to compose a cell membrane, they arrange themselves with their tails facing inward and their heads facing the aqueous environment on either side of the membrane. Therefore, if a hypothetical "microbullet" were to pass through a phospholipid bilayer, it would first pass through the hydrophilic head on the outside, then the hydrophobic tails in the middle, followed by the other layer of hydrophobic tails, and finally the hydrophilic head on the opposite side. The correct sequence would be head >>> tail >>> tail >>> head, which corresponds to option 2 in the provided choices.