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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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