Biochem Module 8 Questions and Answers Graded A

Biochem Module 8 Questions and Answers Graded A True of false: the activated form of glycogen synthase is phosphorylated - ANSWER -false What stabilizes the inactive form of glycogen synthase - ANSWER -G6P Glycogen synthase kinase is under the control of ____ and _____ - ANSWER - insulin, protein kinase A _____ catalyzes the regeneration of UTP from UDP Does this reaction require ATP - ANSWER -nucleoside diphosphokinase Yes __ molecules of ATP are hydorlyzed to incorporate dietary glucose into glycogen. Glycogen-derived glucose generates __ molecules of ATP - ANSWER -2 31 How are glycogen synthesis and breakdown reciprocally regulated? What hormones regulate? - ANSWER -protein kinase A Glucagon and epinephrine Protein kinase A ____ a phosphoryl group to phosphorylase kinase, _____ glycogen breakdown. Glycogen synthase kinase and protein kinase A ____ a phosphoryl group to glycogen synthase, _____ glycogen synthesis. - ANSWER -add, stimulating Add, inhibiting Protein phosphatase 1 (PP1) _____ phosphorylase a and phosphorylase kinase by _____ and ____ phosphoryl groups from glycogen synthase, _____ it. - ANSWER -inactivates, dephosphorylation, removes, activating Insulin ____ glycogen synthesis by ____ glycogen synthase kinase - ANSWER - stimulates, inactivating Glycogen metabolism in the liver regulates ______ - ANSWER -blood-glucose concentration _____ is the glucose sensor in liver cells - ANSWER -phosphorylase a The conversion of phosphorylase a into b is accompanied by the release of PP1, which ____ glycogen synthase and ____ glycogen phosphorylase - ANSWER - activate, inactivate In the preparatory step of fatty acid synthesis, ____ is transferred from the ____, where it is produced, to the ____, the site of fatty acid synthesis. It is transported in the form of ____, which is cleaved to yield _____ and _____. - ANSWER -Acetyl coa Mitochondria, cytoplasm Citrate Acetyl coa, oxaloacetate Fatty acid synthesis begins in the ____, with the activation of ____ in a two-step reaction to _____ - ANSWER -cytoplasm Acetyl coa, malonyl coa Fatty acids are synthesized ___ carbons at a time - ANSWER -2 For fatty acid synthesis ____ carries ____ from ___ to ____ - ANSWER -citrate, acetyl groups, mitochondria, cytoplasm The cleavage of citrate is catalyzed by ____, which is stimulated by ____ - ANSWER -ATP-citrate lyase Insulin What are the three sources of NADPH for fatty acid synthesis? - ANSWER - malate dehydrogenase NAP+-linked malate enzyme Pyruvate carboxylase ____ molecule of NADPH is generated for each molecule of acetyl coa that is transferred from the mitochondria to the cytoplasm. The additional molecules of NAPH needed come from the ____ - ANSWER -one Pentose phosphate pathway The formation of ____ is the committed step in fatty acid synthesis. Catalyzed by ____ - ANSWER -malonyl coa Acetyl coa carboxylase 1 Fatty acid elongation begins when acetyl coa and malonyl coa react with _____ - ANSWER -acyl carrier protein (ACP) Odd numbered fatty acid chains start with _____ - ANSWER -propionyl ACP ____ releases the chain from the carrier protein - ANSWER -thioesterase The synthesis of palmitate requires ___ molecules of acetyl coa, ___ molecules of NADPH, and __ molecules of ATP - ANSWER -8, 14, 7 In tumor cells, the enzymes for fatty acid synthesis are ____ - ANSWER - expressed Enzymes that introduce double bonds are found in the _____ - ANSWER -ER membrane _____ is a key regulator of fatty acid metabolism - ANSWER -acetyl coa carboxylase Acetyl coa carboxylase is turned __ by phosphorylation and turned __ by dephosphorylation - ANSWER -off, on AMP-activated protein kinase converts carboxylase into an ___ form - ANSWER -inactive