Question

If the R group of an amino acid (AA) is a –CH2-OH then the name of this AA is

Select one:

a. Ser

b. Tyr

c. Ala

d. His

e. Trp

Answer 1

Answer: Option "a" Serine

Serine has a hydroxymethyl R group(-CH2-OH) thus making it a polar amino acid. It is also classified as nonessential amino acid because it can be synthesized in the body.

Explanation:

Amino acid are most commonly known as building blocks of proteins, these amino acids are made up of amine group which is basic, carboxyl group which is acidic and an "R group" which is unique to each amino acid. There is a central carbon atom to which the amino and carboxyl groups are attached and there are still 2 bonds remaining which are satisfied by the R group and a Hydrogen atom.

There are different kinds of Amino acids based on the properties of the "R group" attached to the carbon, which include:
1. Nonpolar Amino acids: Alanine, Glycine, Isoleucine,Leucine, methionine, Tryptophan, Phenylalanine, proline and Valine.
2. Polar Amino acids: Cysteine, Serine, Threonine,Tyrosine, Asparagine,Glutamine.
3. Positively charged Amino acids : Histidine, Lysine, Arginine
4. Negatively charged Amino acids : Aspartate, Glutamate

Other options are incorrect because Tyrosine, Alanine, histidine and Tryptophan have " R groups" different from the " R group" of Serine. As mentioned above, The R group is specific to each Aminoacid and therefore, -CH2-OH is a R group of Serine making other options Incorrect.