Carbohydrates Metabolism Flashcards by joseph dizon

The cells that produce NADPH and other simple sugars use an alternative pathway for glucose metabolism

Pentose posphate pathway

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allows for the complete oxidation of the major biomolecules, including glucose

TCA cycle

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used as the electron carrier in fatty acid synthesis or lipogenesis

NADPH

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In the end stages of glycolysis, pyruvate may be converted to lactate with the help of the enzyme

Lactate dehydrogenase

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electron donor in glycolysis

NADH2

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produced per molecule of glucose anaerobically

2 ATP

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produced aerobically

38 ATP

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carries the highest concentration of oxygen and yet is not capable of utilizing a single molecule of it

Red blood cell

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TCA happen in

Mitochondria

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Glycogen

Glucose 6 posphate

5c sugars

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Pyruvate

Amino acid

Lactate

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Acetyl Coa

Fatty acid

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major storage form of glucose

Fatty acids

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Glycogen

Fatty acid

Hydrated

Dehydrated

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terminal 3-carbon molecule (propionic acid) during the beta-oxidation of odd-numbered fatty acids could be converted to the 3-carbon intermediates of gluconeogenesis

dihydroxyacetone phosphate and

diphosphoglyceraldehyde

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Insulin regulates glucose, fatty acid and amino acid metabolism, but it responds primarily to

Serum glucose level

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Insulin inhibits

lipolysis,
beta-oxidation and
gluconeogenesis

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Beta oxidation

Converts fatty acids to energy

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Gluconeogenesis

Break downof amino adis to produce energy

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disaccharides

Sucrose and maltose

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monosaccharides

Glucose and fructose

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Digestion of carbohydrates start as early as when they are being chewed in the mouth since saliva contains

Amylase

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carbohydrates get into the small intestines do much of the digestion takes place with the help of

Pancreatic enzymes

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Absorption of glucose through the intestines occurs primarily through

Fascilitated transport ( sodium )

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Small intestines

Glut 5

Liver, beta cells of pancreas and kidneys

Glut 2

Adipose tissue, heart and skeletal muscle

Glut 4

In order to prevent this, it is immediately phosphorylated to glucose-6-phosphate by the enzyme

Hexokinase

Glucokinase in the liver

Conversion of ____________also decreases the concentration of glucose inside the cell, thus allowing for more glucose to enter

Glucose 6 phosphate

Glucose-6-phosphate has three fates

PPP Glycogen synthesis Glycolysis

PPP

Ribose and other sugar

Glycolysis

Catabolic Glucose to fatty acids Major pathway of energy glucose

in non-hepatic tissues

Hexokinase

In the liver

Glucokinase

has a higher Km than hexokinase and is not inhibited by glucose-6-phosphate

Glucokinase

neither regulated by Insulin nor Glucagon

Hexokinase

stimulates glycogen synthetase

Insulin

Insulin stimulates malonyl CoA synthetase and diverts Acetyl CoA for

Fatty acids synthesis

Decrease glucose

Decrease glucokinase

High km

Glucokinase

Low Km

Hexokinase

Forward reaction catalyzed by

Posphofructokinase

reverse reaction is catalyzed

Fructose 1-6 bi phosphate

stimulates phosphofructokinase 1

Fructose 2-6 bi posphate

Fructose 2,6biphosphate inhibits

fructose-1,6-biphosphatase

because of the lack of inhibition of the enzyme fructose-1,6-biphosphatase by fructose-2,6-biphosphate

Gluconeogenesis

Once pyruvate is formed, it is transported into the mitochondrion where it is converted to acetyl CoA by the enzyme

Pyruvate dehyrogenase

This is strictly an irreversible reaction with the corresponding reaction/s in gluconeogenesis proceeding very differently. The reaction is catalyzed by the enzyme

Pyruvate kinase and produce 1 ATP

inhibited by ATP and the amino acids alanine and phenylalanine

Pyruvate kinase

also regulated by covalent modification and responds to a variety of signals

Pyruvate dehydrogenase

Glycogen metabolism is controlled by regulation of the enzymes

Glycogen phosphorylase

Brain, placenta

Glut 1

Beside to ribose, it is also produce by PPP for lipogenesis

NADPH

Substrate of glycolysis

Glucose

Product of glycolysis

Pyruvate and lactic acid

Substrate of gluconeogenesis

Amino acid

Product of gluconeogenesis

Glucose

also the initial stage in the conversion of glucose into fatty acids

Glycolysis

Enzyme in glucose to glucose 6 phosphate

Hexokinase or glucokinase

When glucose levels are low, glucokinase has very little activity

Because of itshigh Km

ignal for glycogenolysis in the skeletal muscle

Epinephrine

n. a biochemical process, occurring chiefly in the liver and in muscle, by which glycogen is broken down into glucose.

Glycogenolysis

glycolysis part of this reaction

Phosphofructokinase 1

gluconeogenesis part of this reaction

Fructose 1 6 biphosphate

Phosphoenol pyruvate  Pyruvate

Pyruvate kinase

Once pyruvate is formed, it is transported into the mitochondrion where it is converted to acetyl CoA by the enzyme

Pyruvate dehydrogenase

Product of glycolysis

ATP | NADH2

major hormone controlling gluconeogenesis

Glucagon

step which determines the flux between glycolysis and gluconeogenesis

fructose-6-phosphate:fructose-1,6-biphosphate substrate cycle

The removal of the phosphate group is done by an enzyme called ___________. This enzyme is found only in the liver and to a lesser extent in the renal cells

Glucose 6 phosphatase

Enzyme involved in glycogenolysis

Glycogen phophorylase

Enzyme involved in glycogenesis

Glycogen synthetase

helps regenerate reduced glutathione

NADPH

used to generate 3 molecules of ribose using reactions present in the pentose-phosphate pathway

fructose-6-phosphate and 1 molecule of glyceraldehyde-3-phosphate

enzyme catalyzing the first reaction in fatty acid synthesis, the conversion of acetyl CoA to malonyl CoA

Acetyl Coa carboxylase

inhibits acetyl CoA carboxylase thus inhibiting further fatty acid synthesis when fatty acid levels are already high

Actyl Coa

Stimulates acetyl Coa carboxylase | Inhibits acetyl Coa carboxylase

Insulin | Glucagon

When fatty acid synthesis from glucose is taking place, degradation of fatty acids through beta-oxidation in the mitochondrion is prevented by inhibition of

carnitine palmitoyl transferase I (CPT I

Inside the mitochondrial matrix, further fatty acid synthesis from glucose is prevented by Acyl CoA by inhibiting

Cytrate syntethase

citrate synthetase, an enzyme catalyzing the combination of acetyl CoA (from glucose) with oxaloacetic acid to form

Citrate