Biochemical Energy Production METABOLISM

Metabolism

• is a network of metabolic /biochemical reactions.

• Carried out in living cells.

• In a well organized, integrated and regulated manner.

• Related to various biomolecules viz

Energy

Metabolism converts nutrients into _

Simpler forms

Metabolism converts Chemically complex substances of cells into _

Functional complex biomolecules

Metabolism converts Chemically simple substances into _

Phototrophs (Plants)

use light to drive synthesis of organic molecules.

Heterotrophs (Animals)

use these as building blocks.

Catabolism

• Larger molecules broken down into smaller ones (Exothermic)

• Stages 1-4 (Digestion; Formation of Acetyl CoA; Citric Acid Cycle; Electron Transport Chain & Oxidative Phosphorylation)

• Releases energy (may be stored temporarily as ATP)

Anabolism

• Complex molecules synthesized from simpler substances (Endothermic)

• Absorbs energy & stores it as chemical bonds

Amphibolic pathways

• serve both in catabolism and anabolism

• occur at the crossroads of metabolism

• links between Anabolic and Catabolic pathways.

Regulation

means stimulation and inhibition of pathways as per cellular need

Hormones

• regulate the metabolic pathways.

• chemical messengers of human body.

• regulators of Enzyme activity

Enzymes

“Functional units of Metabolism”

Discrete pathways

Enzyme reactions are organized into

Concentration differences

_ keep enzyme-run reactions going in one direction

• Alteration in membrane permeability.

• Conversion of Inactive to Active form.

• Stimulation of mRNA translation. • Induction of new mRNA formation.

• Repression of mRNA formation

Modes Of Enzymes Regulation

Products

Products are constantly removed so no build up at the end. Concentration stays low for

Small steps

Enzymes catalyze oxidation via series of _

Metabolite

is a substrate or a reactant undergoing a biochemical/metabolic reaction

Metabolic reaction

is a biochemical reaction where a metabolite is specifically reacted by an Enzyme and Coenzyme to give a product

Reversible Reactions and Irreversible Reactions

Types Of Metabolic Reactions

Reversible Reactions

Same Enzyme is required. Not regulatory steps.

Irreversible Reactions

• Different set of Enzyme required.

• Non equilibrium Reactions.

• Regulatory steps.

Metabolic pathway

is a series of well defined and significant biochemical reactions followed one after another giving intermediate products and finally end product of the pathway

Compartmentalization of pathways

permits integration and regulation of metabolism.

• Allosteric regulation

• Covalent modification

• Control of enzyme levels

• Compartmentalization

• Metabolic specialization of organs

Modes Of Metabolic Regulation

Feedback inhibitio

product of pathway down regulates activity of early step in pathway

Feedforward activation

metabolite produced early in pathway activates down stream enzyme

Aerobic cellular respiration

In eukaryotic cells, the mighty mitochondrion is where the majority of our energy is grabbed from our food molecules in a process called _

Cellular respiration

Process by which cells convert the energy of fuel molecules (eg. glucose) into usable bond energy in ATP.

Anaerobic respiration

• Fermentation

• Cellular respiration which does not require oxygen

Aerobic respiration

• Cellular respiration which requires molecular oxygen

• Includes redox reactions

Energy

A pyramid of production reveals the flow of _ from producers to primary consumers and to higher trophic levels

ATP

is the most common “energy carrier”

NADH and FADH2

energy carriers

Reaction Coupling

released energy drives an endergonic reaction

ATP Hydrolysis reaction

• Exergonic (spontaneous)

• ATP + H2O → ADP + Pi + H+ ∆G = ~ -30 kJ

Phosphorylation of Glucose reaction

• Endergonic (nonspontaneous)

• Glucose + Pi + H+ → Glucose-Phosphate + H2O

• ∆G = ~ +14 kJ

Coupled Reaction

• Glucose + ATP → Glucose-Phosphate + ADP net ∆G = ~ -16 kJ

• has a net Exergonic effect, so will occur “spontaneously

Coupled

In cells, an exergonic reaction is “_” to an endergonic reaction to give it free energy to drive the reaction

ATP

links exergonic and endergonic reactions

High energy compounds

• _ have greater free energies of hydrolysis than typical compounds

• They contain very reactive (strained) bonds - represented by a squiggle (~)

Loss of Electron, Oxidation, Increase Oxidation No

LEORAION

Oxidized

_ species can gain O or lose H. Substance that becomes oxidized gives up energy

Reduced

_ species can gain H or lose O.

Gain of Electron, Reduction, Decrease Oxidation No.

GEROADON

Redox reactions

Many metabolic pathways use a series of small _ to minimize energy loss.

Energy

_ is transferred in the form of electrons (e- ) in Redox reactions

Sulfhydryl group

The active portion of CoA is the _

Thioester

An acetyl group bonds to CoA through a _bond

1. Glycolysis

2. Formation of acetyl coenzyme A

3. Citric acid cycle

4. Eelctorn transport and cheemiosmosis

Four stages of aerobic respiration

Stage 1

The process of digestion changes. large, complex molecules into relatively small, simpler ones

Stage 2

Small molecules from digestion are degraded to still smaller units, primarily the two-carbon acetyl group that becomes part of acetyl CoA.

Stage 3

Acetyl CoA is oxidized to produce CO, and reduced coenzymes (NADH, FADH) in the citric acid cycle.

Stage 4

NADH and FADH, facilitate ATP production through the electron transport chain and oxidative phosphorylation.

• Nutritional Deficiencies

• Enzyme Defects

• Hormonal Defects

• Drug and Toxin Interactions

Abnormal Metabolism Is Due To

Mutation

_ in Genes of Enzymes, forms defective Enzymes

Inborn Error Of Metabolism.

Congenital defect of Enzyme leads to _

• Using whole organism/Cellular fractions

• Using Metabolic Probes.

• Using Radioisotopes

Methods Used to Study Metabolism