Problem:

Question 1: The fact that during starvation, or after ingestion of a full meal, glucose levels are maintained at a mean of 100 mg % is an example of

a. glucose tolerance

b. homeostatic range

c. hyperglycemia

d. renal glucose extraction

e. none of the above

Quetion 2: Choose a statement from below which is NOT true:

a. Cyclic AMP is a "second messenger"

b. protein phospatases are enzymes that phosphorylate proteins

c. secretion of a substance by a cell is an example of a physiological responce

d. more than one signal transduction cascade can occur in the cell at the same time

e. allosteric hormones can change their shape in response to a regulator

Question 3: Of the following, which is INCORRECTLY paired:

a. Adenylate cyclase/ Cyclic AMP

b. inositol triphosphate/binds to protein kinase C

c. DAG/ binds to protein kinase C

d. calmodulin/regulatory protein

e. none of the above

Question 4: Allostric inhibition refers to:

a. alteration of the catalytic site of an enzyme by covalent binding of a ligand

b. alterations in the activity of the catalytic site by non covalent binding of a ligand at some other site on the enzyme

c. malonate-induced inhibition of succinic dehydrogenase

d. the inhibition of an enzyme by a product of the enzyme reaction

e. direct competiition of two substrates for the active site of the enzyme

Question 5: The term "'second messenger" applies to those substrates that:

a. interact with first messengers inside cells

b. bind to receptors in the cytosol and activate them

c. are secreted by cells in responce to stimulation by a hormone

d. mediate the intracellular responses to many diff hormones and nueromodulators

e. must bing to G proteins in the cytosol before they can produce a responce

Question 6: In order for a macromolecule to be considered a "receptor" it must:

a. be a protein imbedded in the cell membrane

b. form a strong covalent attachment with its ligand

c. be capable of up and down regulation

d. bind a ligand with high affinity and high specificity

e. be able to bind radiolgands as effectively as unlabeled ligands

Question 7: Activation of protein kinase C involved which of the mechanisms listed below:

a. receptor binding-> DAG synthesis-> DAG-PKC binding

b. receptor binding->IP3 synthesis->calcium influx

c. receptor binding->Phospholipase C activation

d. a and b

e. a, b, and c

Question 8: Modification of a protein by an enzymatic phosphorylation is an example of

a. an enzyme turnover number

b. allosteric inhibition

c. covalent modification

d. adenylate cyclase inhibition

Question 9: What is NOT true regarding allosteric regulation?

a. ligand-substrate binding is non covalet

b. the activation of a catalytic site on the enzyme potentiates binding of an allosteric effector

c. the binding of an allosteric modulator can activate or inhibit the catalytic site of the allosteric enzyme

d. an allosteric enzyme is usually a key enzyme in a metabolic pathway

e. none of the above

Question 10: What is NOT true regarding covalent modification by protein kinase

a. It usually involves phosphorylation of one of more amino acid side chains of the substrate

b. phosphatases are enzymes that reverse the action of covalent modification of a substrate by a kinase

c. phosphatases are very substrate specific; kinases have broader specificity

d. when kinases are active, the rate of phosphorylation exceeds that of dephosphorylation

e. kinases are subject to allosteric activation/inhibiation

Give reasoning with your answer.