Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?
A) Enzymatic activity was proportional to the amount of calcium added to a cell-free extract.
B) Receptor studies indicated that epinephrine was a ligand.
C) Glycogen breakdown was observed only when epinephrine was administered to intact cells.
D) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined.
E) Epinephrine was known to have different effects on different types of cells.
Answer: C
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Consider the work Mendel did with his pea plants. Why is the study of human genetics much more difficult? What will be an ideal response?
Maternal PKU can result in serious effects in fetuses. This problem occurs because:a
the fetus is homozygous for PKU and therefore cannot metabolize phenylalanine. b. the fetus is usually homozygous dominant and therefore has PKU. c. the mother is heterozygous for PKU and therefore cannot metabolize phenylalanine. d. the mother is homozygous dominant for PKU and cannot metabolize phenylalanine. e. the mother is homozygous recessive and cannot metabolize phenylalanine
A measure of the average kinetic energy of the molecules making up a substance is known as
A. temperature. B. heat. C. potential. D. phase of matter.