Video Transcript
Which of the following is a primary
function of lipids in animals? (A) Lipids are a major component of
the animal cell wall. (B) Lipids store genetic material
and undergo mitosis to produce new cells. (C) Lipids provide insulation for
cells and organs. Or (D) lipids are the site of
protein synthesis within the cell.
Why are lipids so important in
biology? Well, lipids perform many functions
in living organisms, and in this video, we will be discussing their functions in
animals specifically. Lipids are the major components of
some of our vital organs, like our brains. The primary biological functions of
lipids are to form our cell membranes, to serve as energy storage molecules, and to
provide us with insulation. Let’s briefly review these
functions together before answering the question.
Phospholipid bilayers make up our
cell membranes. As you can tell from its name, a
phospholipid is a type of lipid. Each phospholipid is made of long
hydrocarbon chains that repel molecules of water and are therefore described as
hydrophobic. Each phospholipid molecule also
contains a phosphate head which is hydrophilic, which means it’s attracted to water
molecules and so points outward toward the extracellular space and cytoplasm inside
the cell, both of which contain water molecules.
Other types of lipids, like
cholesterol, help to maintain the fluidity of the phospholipid bilayer to allow it
carry out its function in controlling what can enter and leave the cell. Fatty acids and triglycerides make
up our fat storage that we can use if needed. The bonds between carbon and
hydrogen atoms are considered high-energy bonds, which release a lot of energy when
these molecules are broken down that can be transferred to molecules of ATP.
Lipids are also excellent
insulators: electric insulators and thermal insulators. Maybe you remember that the long
axons of some neurons are covered in a myelin sheath, which is very rich in
lipids. Myelin is an excellent insulator
that allows electrical signals to be conducted faster along the axon without being
dissipated. Lipids are also slow conductors of
heat, so they are good at keeping the heat produced by our body inside. A good example of this is the
important layer of blubber, or fat, that animals living in cold climates tend to
have under their skin.
Although lipids have many important
functions in our bodies, we now know that one of their primary roles is providing
insulation for our cells and organs. So, the correct answer is (C),
lipids provide insulation for cells and organs.
