09 metabolism part 2

7/31/2019 09 Metabolism Part 2

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BIOENERGETICS Part 2HOW THE BODY CONVERTS FOOD TO ENERGY


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GLUCONEOGENESIS

Production of glucose from non-carbohydrate sources

Lactate

All amino acids except leucine and lysine

Glycerol from fats

Amino acids and glycerol are used only understarvation conditions

Occurs primarily in the liver


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CORI CYCLE


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GLYCOGENESIS

Formation of glycogen from glucose

Occurs in the liver

Influenced by insulin

Inhibits glycogen phosphorylase

Stimulates glycogen synthase andglucokinase


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GLYCOGENOLYSIS

Breakdown of stored glycogen to formglucose

Influenced generally by glucagon andepinephrine in response to low bloodglucose levels

Glycogen phosphorylase is activated

Glycogen synthase is inhibited


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(2) CITRIC ACID CYCLE

Also known as the Krebs Cycle

Final stage of the breakdown of

carbohydrates, fats, and amino acids.

Series of enzymes involved


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KETONES

Formed from beta-oxidation pathway offatty acid metabolism due to low level ofglucose (starvation and fasting)

Low glucose supply slows down citricacid cycle

No glycolysis

No PEP production

Greatly reduced oxaloacetate production As a result, acetyl CoA builds up in the

body


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(3) OXIDATIVE PHOSPHORYLATION

Is a series of reactions which couples theoxidation of NADH and FADH2 to thephosphorylation of ADP to generate ATP

NADH = used to produce 3 ATPs

FADH2= used to produce 2 ATPs


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NUMBER OF ATP PRODUCED BY THECOMPLETE OXIDATION OF ONE MOLECULE

OF GLUCOSE

Glycolysis Substrate-level Phosphorylation 2 ATP

2 NADH x 2 ATP/cytoplasmic NADH 4 ATP

Conversion of 2 pyruvate molecules to 2acetyl CoA molecules

2 NADH x 3 ATP/NADH 6 ATP

Citric Acid Cycle

2 GTP x 1 ATP/GTP 2 ATP

6 NADH x 3 ATP/NADH 18 ATP

2 FADH2 x 2 ATP/FADH2 4 ATP


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CATABOLISM OF THE NITROGENOF AMINO ACIDS

Dietary proteins are hydrolyzed to aminoacids in digestion

Amino acids are primarily used tosynthesize new proteins

Cannot be stored, so excess amino acidsare catabolized for energy production inthe liver

1. Transamination2. Oxidative Deamination

3. Urea Cycle


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TRANSAMINATION

Amino acids transfer their amino group toalpha-ketoglutarate


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OXIDATIVE DEAMINATION

Oxidative deamination of glutamate


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UREACYCLE

Ammoniaisconvertedto urea


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CATABOLISM OF HEME

Red Blood Cells 80 120 days life span

Destroyed by the phagocytic cells

Hemoglobin is metabolized Globin is hydrolyzed to amino acids

Heme is oxidized to biliverdin andfinally reduced to bilirubin

Bilirubin enters the liver

Iron is preserved in ferritin and reused


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09 metabolism part 2

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