A high glucose meal cause release of insulin which results in greater rates of s

Question

A high glucose meal cause release of insulin which results in greater rates of synthesis of phosphoprotein phosphatase. Glycogen synthase, a key enzyme of glycogen synthesis, then becomes activated after the phosphatase catalyzes activation of this enzyme. What two types of enzyme regulation are described here? (choose the two answers) a) genetic control b) allosteric regulation c) zymogen synthesis and activation d) reversible covalent modification e) irreversible inhibition Which of the following are characteristics of enzyme regulation by modulators intending noncovalently with enzymes? a) feedback inhibition b) zymogen activation c) enzyme induction (synthesis) d) allosteric regulation e) activation of zymogens f) synthesis of enzymes of lactose simulation in E coli g) phosphorylation of glycogen phosphorylase Which of the following are characteristics of enzyme regulation by covalent modification of the enzyme? a) feedback inhibition b) zymogen activation c) enzyme induction (synthesis) d) allosteric regulation c) activation of zymogens f) synthesis of enzymes of lactose stimulation in E coli g) phosphorylation of glycogen phosphorylase Which of the following statements about isoenzymes are true? a) isozymes have different primary structures; b) isozymes have identical a allosteric regulators c) isozymes are encoded by the same gene (UNA) d) isozymes catalyze different chemical reactions e) isozymes are present in different levels in various developmental stages f) isozymes catalyze different reactions g) lactate dehydrogenase (LDH) is an example The standard free energy changes for the reactions below are given: Phosphocreatine + H_O rightarrow creative + Pi Delta G degree = - 43.0 kJ/mol ATP + H_2 O rightarrow ADP + Pi Delta G degree = - 30.5 kJ/mol What is the overall Delta G degree for the following reaction? Phosphocreatine + ADP rightarrow creative + ATP (choose one best answer) a) - 73.5 kJ/mol; b) - 12.5 kJ/mol c) + l2.5 kJ/mol d) + 73 5 kJ/mol e) 0 kJ/mol Which of the following pathways would be considered Stage 2 catabolism? a) Hydrolysis of starch catalyzed by amylase to yield glucose; b) Glycolysis c Oxidation of fatty acids to release acetyl CoA d) Pentose phosphate pathway e) Citric acid cycle f) Hydrolysis of peptide bonds of proteins to release amino acids g) Electron transport and oxidative phosphorylation. Which of the following are characteristics of anabolic metabolic pathways? a Convert small compounds into larger compounds; b) Require input of ATP c) Net production of ATP as a result of the pathway d) Convert NADPH to NADP e) Convert NAD^+ to NADH f) Convert large compounds to smaller compounds g) the pathways are overall exergonic (negative Delta G) Which of the following are considered aerobic metabolic pathways? a) glycolysis b) gluconeogenesis c) citric acid cycle (TCA) d) electron transport e) oxidative phosphorylation f) fatty acid oxidation g) pentose phosphate pathway

Explanation / Answer

17.option B

Glycogen synthase is activated allosterically by G6P.It is deactivated with phosphorylation by cAMP-dependent protein kinase (cAPK) and other kinases.It is activated with dephosphorylation by phosphoprotein phosphatase-1.
When glucose is high Glucagon level is decreased,and insulin is secreted from pancreas.At many cells except for liver cells, insulin-sensitive endo/exocytosis mechanism is activated,and glucose transports are exposed on the plasma membrane by exocytosis.The high glucose flows into the cells through the glucose transports and resulting glucose is converted to glycogen.Insulin-stimulated kinase is activated by insulin’s signal.Activated insulin-stimulated kinase phosphorylates the G-subunit of phosphoprotein phosphatase (PP-1),and activates it.Activated PP-1 dephosphorylates glycogen synthase,and activates it.Also the PP-1 dephosphorylates glycogen phosphorylase and deactivates it to reduce glycogen breakdown.At the liver cells,glucose is freely permeable,and in addition to the PP-1 activity,glucose itself inhibits glycogen phosphorylase.Also by dephosphorylation of phosphoprotein phosphatase inhibitor-1 release PP-1 to increase the PP-1 activity (i.e.increase glycogen synthesis).Although individual cells can store glycogen,liver stores most of the excess of glucose as glycogen.

18.option D

Allosteric enzymes function through reversible,non-covalent binding of regulatory compounds called allosteric modulators or allosteric effectors,which are generally small metabolites or cofactors.Allosteric regulation is the regulation of an enzyme or other protein by binding an effector molecule at the protein's allosteric site (that is, a site other than the protein's active site).Allosteric enzymes undergo conformational changes in response to modulator binding. The modulators for allosteric enzymes may be stimulatory or inhibitory.Regulatory enzymes for which substrate and modulator are identical are known as homotropic enzymes.Heterotropic enzymes have substrate other than the modulator.Allosteric enzymes are generally larger and more complex than non-allosteric enzymes. Their properties are significantly different from those of simple non-regulatory enzymes.Allosteric enzymes have one or more regulatory sites other than the active site for binding with the modulator.As the active site in an enzyme is specific for its substrate,similarly,each regulatory site is specific for its modulator.Homotropic enzymes have the active site which is same as the regulatory site.

19.option g

20 option a and G

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