Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to
A) the active site of an enzyme in the cytoplasm that binds to a specific substrate.
B) RNA specifying the amino acids in a polypeptide.
C) a particular metabolic pathway operating within a specific organelle.
D) an enzyme with an optimum pH and temperature for activity.
E) genes making up a chromosome.
Answer: A