Mechanisms for controlling enzyme activity include all of the following EXCEPT .a. covalent modification of the enzyme. b. feedback inhibition. c. degradation of the enzyme. d. addition of short sections of new amino acid sequence.

What is the significance of the protein-lined pits? a. protein attracts other proteins needed for atp synthesis within the cell. b. protein-lined pits are able to transport one molecule at a time down the concentration gradient within the cell. c. the polarity of proteins allows other polar molecules to attach and be transported in the cell by transport channels. d. receptors within the pits allow ligands to fuse and be transported into the cell by endocytosis.