Question

free response

1. explain at least three functions that lipids serve in plants and/or animals.
2. explain what happens if even one amino acid is substituted for another in a polypeptide chain. provide a specific example.

Explanation:

1. Lipids perform energy storage, structural, and signaling roles. 6) Amino acid substitution alters protein structure/function; example: sickle-cell anemia.

Answer:

1. Three functions of lipids: 1) Energy storage (e.g., triglycerides in animal fat, oils in plant seeds). 2) Structural components (e.g., phospholipids forming cell membranes). 3) Signaling molecules (e.g., steroid hormones like estrogen regulating physiology).
2. Substituting one amino acid changes polypeptide structure/function due to differing properties (e.g., charge, hydrophobicity). Example: Sickle-cell anemia—glutamic acid (hydrophilic) replaced by valine (hydrophobic) in hemoglobin causes abnormal fiber formation, sickle-shaped red blood cells, and impaired oxygen transport.