Final answer:
During the tanning process, the amino acid present is tyrosine, which serves as a precursor for melanin production.
Step-by-step explanation:
In the tanning process, the amino acid tyrosine is present. Tyrosine serves as a precursor for the production of melanin, the pigment responsible for skin and hair color. During tanning, tyrosine is converted into another amino acid called melanin through a series of enzymatic reactions. This melanin then accumulates in the cells of the skin, resulting in darkening or tanning of the skin.