Question

which three components are common to all amino acids?
o an amino group, a carboxyl group, and an r group
o an amino group, a phosphate group, and an r group
o a five - carbon sugar, a phosphate group, and a nitrogenous base
o a five - carbon sugar, an amino group, and a nitrogenous base

Explanation:

Amino acids are the building blocks of proteins. The general structure of an amino acid has a central carbon atom (alpha - carbon). Attached to this central carbon are an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and an $R$ group (which varies among different amino acids).

• Option 2: Phosphate group ($-PO_4^{2 - }$) is not a part of the basic structure of amino acids. It is more commonly associated with nucleotides (like in DNA and RNA).
• Option 3: Five - carbon sugar (ribose or deoxyribose), phosphate group, and nitrogenous base are components of nucleotides, not amino acids.
• Option 4: Five - carbon sugar is not a part of amino acid structure. Amino acids have an amino group, carboxyl group, and $R$ group attached to the central carbon.

Answer:

an amino group, a carboxyl group, and an R group