A titratable group is in the active site of an enzyme and must be protonated for the enzyme to function. Assume that the group has a pKa of 6.5 and that the activity is proportional to the fraction of molecules in the protonated state. Which of the following are true? 1. At pH 9.0 close to 100% of the enzyme molecules are active.
2. At pH 9.0 close to 100% of the enzyme molecules are inactive.
3. At pH 6.5 the enyzme is 50% active.
4. At pH 6.8 the enzyme is 66.6% inactive.5. At pH 7.2 there are about 5 inactive enzymes for every active enzyme.

Hormones are chemical molecules produced by endocrine glands. one such endocrine gland is the thyroid gland, which synthesizes the thyroid hormone, which in turn affects the heart muscles. which two statements describe the probable reason for the function of the hormone? the cells in the heart have specific receptors that allow for the intake of hormones. the heart and the endocrine glands have the exact same types of cells. all cells make the same types of hormones. thyroid hormones show their effect on the heart by means of specialized cells. thyroid cells and cardiac cells have different dna.