Video Transcript
Which of the following most
accurately describes the basic structure of a biological macromolecule? (A) Biological macromolecules
are molecules or monomers that are made up of repeating units or polymers. (B) Biological macromolecules
are long or large molecules or polymers that are made up of smaller subunits or
monomers joined together. Biological macromolecules are
small molecules or polymers that are made up of smaller atoms or monomers joined
together.
The correct answer to this
question will be the choice that describes the structure of a biological
macromolecule. And since we’re looking for the
choice that does this the most accurately, we’re going to need to compare all
three answer choices to each other. When we say that a molecule is
biological, we usually mean that it’s organic or that it possesses carbon to
hydrogen bonds. A molecule is two or more atoms
bonded together, and macro- is a word part that means large. So a biological macromolecule
is going to be a large group of atoms bonded together that’s organic.
You’re likely aware that all
living organisms are made of cells, that cells contain many organelles,
organelles are built out of molecules, and we’ve already mentioned that
molecules are made out of two or more atoms bonded together. On our scale of biological
organization, macromolecules would fit right here. So a macromolecule is a large
molecule, which is made up of lots of smaller units, which are molecules
themselves. Many macromolecules are also
considered to be polymers. Poly- is a word part that means
many, and -mer means unit. And those molecular subunits
that make up the polymer are referred to as monomers. Mono- is a prefix that means
one.
A good example of this is a
macromolecule called glycogen. Glycogen is a carbohydrate
polymer made of many repeating subunits bonded together. The monomers that are bonded
together to form glycogen are glucose molecules. So each of these pairs of terms
has the same relationship. Glycogen is made of
glucose. Polymers are made of
monomers. And macromolecules are made of
molecules. Now let’s go back to our answer
choices.
Our first choice says that
monomers are made up of polymers. But we know that monomer is one
unit and polymer is many. So this answer choice is
incorrect. Our second choice says that
macromolecules are large molecules, which we know is true, and also that
polymers are made up of monomers, which is also correct. So this answer choice seems
okay. But since we’re looking for the
most accurate, we need to compare all three. Our last choice states that
macromolecules are small molecules, but we know that the word part macro-
actually means large. So this answer choice is also
not correct.
The choice that best describes
the basic structure of a biological macromolecule is biological macromolecules
are long or large molecules or polymers that are made up of smaller subunits or
monomers joined together.
