Amino Acids vs. Nucleotides

Key structural features and bonding of the two primary biological monomers.

What are the three components of a nucleotide?

1. A pentose sugar (ribose or deoxyribose)

2. One or more phosphate groups

3. A nitrogenous base (adenine, guanine, cytosine, thymine, or uracil)

Which four groups are bonded to the α-carbon of a standard amino acid?

1. An amino group (-NH₂)

2. A carboxyl group (-COOH)

3. A hydrogen atom (-H)

4. A variable R-group (side chain)

What type of covalent bond joins amino acids together in proteins?

A peptide bond forms between the carboxyl carbon of one amino acid and the amino nitrogen of the next.

What type of covalent bond joins nucleotides together in nucleic acids?

A phosphodiester bond links the 5′ phosphate of one nucleotide to the 3′ hydroxyl of the next nucleotide’s sugar.

True or False: All amino acids contain a nitrogenous base.

False. Amino acids contain an amino group, but they do not have a nitrogenous base—that feature is specific to nucleotides.