BIOC 3300 Lecture Notes - Lecture 4: Glycogen Phosphorylase, Glycogen Synthase, Pyridoxal Phosphate

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coffeeoyster95

13 Jan 2016

School

Dalhousie University

Department

Biochem & Molecular Biology

Course

BIOC 3300

Professor

Mc Leod Roger

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Document Summary

About 2-8% of liver weight is glycogen: the major energy source for contraction of skeletal muscle, the major energy source stored in the liver to maintain blood glucose. Phosphorolysis of -1,4-glycosidic linkages of the glycogen polymer. Catalyses the reaction releasing glucose-1-p from the non-reducing end of glycogen. Cannot break down 1,6 linkages at branch points. Phosphorylase stops at a point 4 glucose residues away from the branchpoint. Released ppi is hydrolysed to 2pi by abundant pyrophosphatase, driving reaction to ompletion. The reaction is a phosphoanhydride exchange in which the phosphoryl oxygen of g1p attacks the phosphorus atom of utp to form udpg and release ppi. The ppi is rapidly hydrolyzed by inorganic pyrophosphatase. Glycogen assembly is initiated by addition of a short chain (up to 8) of glucose residues onto the protein glycogenin. glycogenin-glucose chains serve as. primers for glycogen synthase to extend with additional udpglucose units. Lec 4 slides - glycogen metabolism and gluconeogenesis.

Related Questions

16. Muscle glycogen cannot contribute directly to blood glucose levels because:

A. Muscle glycogen cannot be converted to glucose-6-phosphate

B. Muscle lacks glucose-6-phosphatase

C. Muscle contains no glycogen phosphoyrlase

D. Muscle lacks phophoglucoisomerase

_____17. Which of one of the following tissues requires insulin for glucose transport into the cell?

A. Brain

B. Liver

C. Skeletal muscle

D. Red blood cells

_____18. The mobilization of triaclyglycerol-bound fatty acids from adipose tissue and their subsequent oxidation by muscle mitochondria require all of the following compounds except:

A. Serum albumin

B. Carnitine

C. Acetyl CoA carboxylase

D. Hormone sensitive lipase

_____19. Which one of the following reactions is unique to gluconeogenesis?

A. Lactate Â® pyruvate

B. PhosphoenolpyruvateÂ® pyruvate

C. OxalacetateÂ® Phosphoenolpyruvate

D. 1,3bisphosphoglycerate Â® 3-phosphoglycerate

_______20. A newborn vomits after each feeding of milk-based formula and doesnât gain weight. Biochemical testing reveals a sever deficiency of galactose-1-phosphate uridyltransferase. If this condition goes untreated, which of the following is the likely outcome for this patient?

A. Benign disease except for cataract formation

B. Chronic emphysema appearing in early adulthood

C. Chronic renal failure appearing in adolescence

D. Death in infancy

E. Gastrointestinal symptoms that remit with puberty

10- With respect to regulation of fatty acid metabolism chose the FALSE statement from those below?

a) ACC and FAS synthesis is stimulated by Insulin

b) ACC and FAS synthesis is stimulated by the well-fed state

c) Starvation leads to an increase in the synthesis of ACC and FAS.

d) Adipose tissue levels of lipoprotein lipase also are increased by insulin and decreased by starvation.

e) The long-term regulation of fat metabolism is achieved by alteration of the rate of enzyme synthesis and turn-over

14-With respect to the clinical significance of ketogenesis, which of the statements below are FALSE?

a) The Ketone bodies are relatively strong acids

b) The increase of ketone bodies in the blood lowers the pH of the blood.

c) The acidification of the blood by an increase of ketone bodies in the blood is dangerous because it impairs the ability of hemoglobin to bind oxygen

d) A severe increase of ketone bodies in the blood occurs in untreated insulin-dependent diabetes mellitus.

e) none of the above

15-With respect to ketogenesis, which statement below is FALSE?

a) Acetoacetate and b-hydroxybutyrate are major substrates for the biosynthesis of neonatal cerebral lipids.

b) In early stages of starvation, the heart and skeletal muscle consumes primarily ketone bodies to preserve glucose for use by the brain.

c) The fate of the products of fatty acid metabolism is determined by an individual's physiological status.

d) Ketogenesis takes place only in the liver.

e) all of the above

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BIOC 3300 Lecture Notes - Lecture 4: Glycogen Phosphorylase, Glycogen Synthase, Pyridoxal Phosphate

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