Video: Describing the Basic Structure of Proteins, Carbohydrates, and Nucleic Acids in terms of Being Biological Macromolecules

Which of the following most accurately describes the basic structure of a biological macromolecule? [A] Biological macromolecules are molecules (monomers) that are made up of repeating units (polymers). [B] Biological macromolecules are long or large molecules (polymers) that are made up of smaller subunits (monomers) joined together. [C] Biological macromolecules are small molecules (polymers) that are made up of smaller atoms (monomers) joined together.

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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.

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