18. Amino Acids and Proteins

What kind of biological function would each of the following proteins perform?

a. Human growth hormone

Name four biological functions of proteins in the human body, and give an example of a protein for each function.

Cortisol levels rise under stressful conditions. Oxytocin can induce relaxation and romantic feelings. What type of protein are cortisol and oxytocin?

Alcohol dehydrogenase, found in liver cells, converts ethanol into acetaldehyde. What type of protein is alcohol dehydrogenase?

Draw the structure of the following amino acids, dipeptides, and tripeptides at low pH (pH 1) and high pH (pH 14). At each pH, assume that all functional groups that might do so are ionized.

d. Glu-Asp

Examine the ball-and-stick model of valine below. Identify the carboxyl group, the amino group, and the R group.

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