11.13 (dr. saleem) overview of metabolism & bioenergetics ii oidative phosphorylation & electron transport chain

We have indeed created man in the best shape(Holy Quran)

Lecture # 2 BiochemistryFoundation Module

November-2010

Growth and reproduction and all other vital process depend on Hundreds of

planned chemical reactions called metabolic reactions

Energy is fundamentalrequirement of living systems

Energy can be produced by actual burning of organic substances in air (Oxidation or Combustion).

Such energy is not suitable for living systems because:Can not be controlled.Can not be stored.Requires drastic conditions.

In living system energy is generated by precise chemical methods

Energy produced by such chemical methods:

Is Precisely controlled and regulated according to requirements.

Can be stored for use at a proper time.

Do not require drastic conditions of Temperature, Pressure and pH.

Bioenergetics(Biochemical thermodynamics)

Study of the energy changes accompanying biochemical reactions.

Study of generation, storage and utilization of energy in living system.

Sources of Energy In Human cells

Free or useful energy is released during catabolic reactions:

Oxidation of energy-rich organic compounds (Cellular respiration):

Glucose

Fats (Glycerol & Fatty acids).

Amino acids.

Storage of energy in living systemFree or useful energy is released

during catabolic reactions.

This energy is captured and stored as high energy phosphate bonds.

Compounds having high energy bonds are called high-energy compounds.

Adenosine Triphosphate (ATP)is the most commonly usedEnergy Storing Molecule

Adenine|Ribose_______P

Adenosine Monophosphate

~ P ~ P

High Energy Phosphate Bonds

Capture of Energy as ATP

Adenine

|

Ribose_______P ~ P ~ PEnergy generated by oxidation of food

stuffs is utilized for the formation of High- energy phosphate bonds.

ADP is converted to ATP

Release of energy by ATP

Adenine|Ribose_______P ~ P ~ P

Hydrolysis of terminal Generates 7300 Calories.ATP is Converted to ADP

Release of energy by ATP

Phosphate bond splits to release free energy Approximately 7300 cal/mol. for each of two terminal phosphate groups.Adenosine diphosphate (ADP) and

Adenosine monophosphate (AMP) are formed respectively.Phosphate bond of AMP is a low-

energy bond.

Release of energy by ATP

Adenine|Ribose_______P ~ P + Pi

Energy generated is utilized for:1. Metabolic Reactions.2. Muscle Contraction.3. Heat.

Catabolism of Nutrients

CO2 + H2O

Energy

Adenine|Ribose__P

Adenosine Monophosphate

Adenine|Ribose__P __P

Adenosine Diphosphate

Adenine|Ribose__P __P __P

Adenosine Triphosphate

An Overview of Energy Storage

ATP / ADP Cycle

Adenine |Ribose — P ~ ~ ATP

Adenine |Ribose — P ~ ADP

7300 cal/mol

ATP as energy currency-----------------------

ATP acts as currencyof energy, when energy

is gained from high-energymolecules, is stored in

this form and it pays it to low-energy molecules,

when required.

Organic molecules (Nutrients Such as Glucose & Fats) contain energy, stored

in their molecular structure

Catabolism of these molecules generate the energy to synthesize High-energy

Phosphate bonds (ATP)

Generation and utilization of energyin human tissues is an important

concern in medical science Medical problems due to energy imbalance:

StarvationUnavailability of Energy

ObesityExcess Storage of Energy

MarasmusEnergy imbalance due to Malnutrition

Hormonal DisordersDiabetes mellitus, Diseases of Thyroid

Cellular Respiration is theMain Source of Energy

The overall process of energy generation by breakdown of food is called Cellular Respiration.The process by which the chemical

energy of food molecules (Carbohydrates, Fats, and Proteins) is released and captured in the form of ATP.

Cellular respiration is a complex biochemical phenomena backed up by:

Feel the difference between breathing and respiration!Merely inhalation of Oxygen and

expulsion of carbon dioxide is not respiration.

Respiratory System

Digestive System.

Blood circulatory System.

To generate energy through Cellular respiration a cell must have:

Required amount of Oxygen.Sufficient quantity of energy

generating molecules.Required enzymes in cytosol and

Mitochondria.Certain derivatives of vitamins such

as Thiamin, Niacin and Riboflavin).

Role of Carbohydrates, Fats, and Proteins Cellular Respiration

Carbohydrates Proteins Fats

Glucose Amino acids Fatty acidsGlycerol

CO2 + H2O + ATP (Energy)

Breakdown (Catabolism) of molecules generate the energy to synthesize ATP

Direct At Substrate Level:At the time of reaction ADP is converted to ATP.

Indirect Through Biological Oxidation:

Hydrogen atoms generated during reaction go through a complex process of biological oxidation.

Metabolic Processes InvolvedIn Cell Respiration

Glycolysis; occurs in cytosol.

Oxidation of Fatty acids and Krebs Citric acid Cycle occur in Matrix of Mitochondria.

Biological Oxidation occurs in Inner Membrane of Mitochondria.

Two types of Cellular Respiration

Aerobic Respiration.

Anaerobic Respiration.

Aerobic Respiration

Final Oxidizing agent (Electron Acceptor) is Oxygen.The most Important Metabolic Source

of Energy in Living cells (Exceptions?)Contributes approximately 90% of

total energy generated in cell.Net result is CO2, H2O and Energy

(ATP & Heat)

Anaerobic Respiration

Final Oxidizing agent (Electron Acceptor) is Other than Oxygen.

Important Source of Energy in cells Not Having Mitochondria (RBC).Cells Deprived of Oxygen (Exerting Muscles & Ischeamic Tissues)

A number of NAD and FAD molecules are reduced by H+ generated

during Glycolysis, Oxidation of Fatty acids and Krebs Citric acid Cycle

In various reactions of Glycolysis, Citric acid cycle and Oxidation of Fatty acids Hydrogen atoms are removed from the substrate and accepted by co-enzyme NAD and FAD.

Biological oxidation in the mitochondria is the final and most important step of

cellular respirationReduced NAD (NADH) and Reduced

FAD (FADH) ultimately pass their Hydrogen to Oxygen to form water

During this complex process elctron of hydrogen atom is seprated and takes part in genertaion of energy in the form of ATP

Cellular RespirationGlycolysis, Oxidation of Fatty acids and catabolism of Amino acids

Citric Acid Cycle

NADH FADH2

BiologicalOxidation

ADP ATP

The Final Stage of Cellular Respiration called

Biological Oxidation

The Oxidation of NADH2 & FADH

generates as high as 90% of total

energy generated by complete setup of

Cellular Respiration.

Biological Oxidation

Biological mechanism for the synthesis of ATP, Takes place in Inner Mitochondrial Membrane.Includes two integrated mechanisms

Respiratory Chain, extracts energy from electrons of Hydrogen.Oxidative Phosphorylation, utilizes extracted energy for the formation of high-energy bond.

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