TCA _ مقررات المستوى الثالث كليه الطب _ Biochemistry

The Three Stages of Respiration

• Stage I All the fuel molecules are oxidized to 

acetyl-CoA.

• Stage II :Acetyl-CoA is completely oxidized into CO2

electrons are collected by NAD and FAD via the  electrons are collected by NAD and FAD via the 

citric acid cycle.

• Stage III  Passage of electrons through the electron 

transport system to yield ATP from oxidative 

phosphorylation

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Pyrovate Oxidation_مقررات المستوى الثالث كليه الطب _Biochemistry

ANAEROBICALLY GLYCOLYS

Respiratory chain is absence

+Reoxidation of NADH NAD

via Respiratory 

chain is inhibited

Reoxidation of NADH via lactate formation 

allows glycolysis to proceed in the absence of 

+oxygen by regenerating sufficient NAD

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GLYCOLYSIS _مقررات المستوى الثالث كليه الطب _ Biochemistry

Contents

• Introduction: CHO metabolism.

• CHO: Digestion and Absorption.

• CHO: Metabolic Pathways

1-Glycolysis.

2-Tri carboxilic  Acid (TCA).

3-Electron Transport Chain (ETC).

4-Oxydative Phosphorylation (O.P.)

5-Glycogen Metabolism.

6-Pentose Phosphate Pathway (PPP).

7-Gluconeogenesis.

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ETC& OP _ مقررات المستوى الثالث كليه الطب _Biochemistry

Mitochondria

• Outer membrane relatively permeable

• Inner membrane permeable only to those 

molecules with specific transporters

2– Impermeable to NADH and FADH

– Permeable to pyruvate

• Compartmentalization

– Kreb's and β-oxidation in matrix

– Glycolysis in cytoplasm.

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Vit final 2014/مقررات المستوى الثالث .كليه الطب .Biochemistry

Vitamins are necessary components of healthy 

diets and play important roles in cellular 

metabolism. 

• Vitamins are considered “micronutrients.” 

• Although these substances occur in only very 

small amounts within cells, they are critically 

important.  Their absence is usually 

manifested as some deficiency disease. 

•? What are vitamin

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Introduction to Metabolism 2014 / مقررات المستوى الثالث .كليه الطب .Biochemistry

Contents

Introduction 

 General Principals of Metabolism 

 General Motifs of Metabolism 

ATP: Universal Currency of free energy 

Activated Carriers 

Key Reactions 

Regulation 

Metabolism : Definition

“The sum of ALL the chemical 

processes occurring in an organism at 

one time” 

Concerned with the management of 

material and energy resources within 

the cell 

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Enzymes 2014 / مقررات المستوى الثالث .كليه الطب .Biochemistry

Contents 

Introduction. 

Why Enzymes Are Needed . 

Mechanism of Enzyme Action. 

Enzymes Properties. 

Nomenclature & Classification. 

Factors affecting Enzymes. 

Enzyme Regulation. 

Enzyme Inhibition.

Enzymes: Definition

Enzymes are organic catalysts that speed up 

the rate of a chemical reaction without being 

permanently altered in the process. 

• The  first  enzyme  was  isolated  in  1833  by 

Payen  and  Persoz  from  barley  seeds.  Called 

diatase, it converts starch to sugars. 

• Buchner:  en-zyme,  German  languge: 

“something in yeast”

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