Metabolism

Catabolism-Glycolysis (Kreb

Cycle)

Anabolism-Photosynthesis

Metabolism

• Sum of all chemical reactions

• Catabolism

– Exergonic reaction

– Most of energy in ATP –last phosphate bond

Metabolism

• Anabolism

– Consume more energy than produce

– Use ATP for energy

Enzymes

• Biological catalysts

• Energy of activation

• Specificity

• Primary structure

• Secondary structure

• Tertiary structure

• Quaternary structure

Components of Enzymes

• Apoenzyme-protein only

• Cofactor-nonprotein

– Trace elements

• Coenzyme-organic cofactor

– Carriers of electrons etc

– NAD+

Enzyme-substrate Complex

• Active site on enzyme

• Transformation in substrate

• Products released

• Enzyme orients substrate

• Lowers energy of activation

Denaturation

• Structure of enzyme is disrupted

• No longer active

• Temperature

• pH

• Substrate concentration

– Enzyme becomes saturated

Inhibitors

• Competitive inhibitors

• Noncompetitive inhibitors

– Allosteric site

Feedback Inhibition

• End product inhibition

• Series of enzymes –end product

Energy Production

• Oxidation-reduction reactions

• Generation of ATP

– Phosphorylation

– Used for metabolism, binary fission,

endospore formation movement

Types of Phosphorylation

• Substrate level

• Oxidative phosphorylation

• Photophosphorylation

Carbohydrate Metabolism

• Glucose as an example

• Two energy processes

– Cellular respiration

– Fermentation

– Glycolysis

• Respiration-Krebs cycle & electron transport chain

Glucose Metabolism

C6H12O6 + 6O2 + 38 ADP +38 P

6CO2 + 6H2O + 38 ATP

Glycolysis

• Summary of glycolysis

• 2 molecules of pyruvate (3 C)

• Production of 2 NADH & 2H+

• Net of 2 ATP

• Substrate phosphorylation

• Takes place in cytosol of bacteria & eukaryotes

• No oxygen is required

• Alternate pathways

Cellular Respiration

• Cellular respiration

– Final electron acceptor is inorganic molecule

• Two types based on final electron

acceptor

Aerobic Respiration

• Krebs cycle

• Mitochondria of eukaryotes-matrix

• Cytosol in prokaryotes

• Intermediary step- production of acetyl

CoA

– 2 CO2 & 2 NADH

Aerobic Respiration

• Acetyl Co enters Krebs cycle

• 4 carbons of glucose released as CO2

• 6 NADH & 2 FADH2 produced

• 2 ATP by substrate phosphorylation

Electron Transport Chain

• Series of redox reactions

• Stepwise release of energy

• Oxygen final acceptor of electrons

• Inner membrane of mitochondria in eukaryotes

• Foldings of plasma membrane or thylakoid

infoldings( photosynthesis)

• Occurs only in intact membranes

Carrier Molecules

• Some carry both electrons & protons (H+)

• Cytochromes transfer electrons only

• Oxygen is last link of chain

Chemiosmosis

• ATP generation

• Proton pumps

• Proton motive force

• Protein channels with ATP synthases

ATP Production

• Protons release energy as rush through

pore

• 3 ATP per NADH

• 2 ATP per FADH2

• ATP produced via oxidative

phosphorylation

• Damage to membrane ceases proton

movement

Anaerobic Respiration

• Final electron acceptor is an inorganic

molecule other than oxygen

• Some use NO3 - ,SO4

2-

• Important in nitrogen and sulfur cycles

• ATP varies, less than 38

• Only part of Krebs cycle & ETC used

Fermentation

• Pyruvate converted to organic product

• NAD+ regenerated

• Doesn’t require oxygen

• Does not use Krebs cycle or ETC

– Shut down

• Organic molecule is final electron acceptor

• Produces 2 ATP max

Photosynthesis

• Conversion of light energy into chemical

energy

• Anabolism (carbon fixation)-produce

sugars from CO2

• Two stages

Overall Reaction

6CO2 + 6H2O + ATP

C6H12O6 + 6O2 + ADP + P

Light Reactions

• Photophosphorylation-production of ATP

– Only in photosynthetic cells

• Light energy (electromagnetic radiation)

absorbed by chlorophylls

– Chlorophyll a in plants, algae and cyanobacteria

– Located in membranous thylakoids of chloroplasts-

plants & algae

– Infoldings of plasma membrane of cyanobacteria

Light Reactions

• Electrons flow through ETC

• Electron carrier is NADP+

• ATP produced by chemiosmosis

Noncyclic Photophosphorylation

• Plants, algae, cyanobacteria

• 2 photosystems

• Produce both ATP via chemiosmosis

• Produce NADPH

– Used to reduce CO2 in dark reactions

– Able to produce sugars

Summary

• ATP produced by chemiosmosis

– Uses energy released in ETC

• Oxygen produced from splitting of water

– H2O→ 2H+ +2 e + O

– Replace electrons lost from chlorophyll

• NADPH produced in second photosystem

Dark Reactions

• Calvin-Benson Cycle

• Requires no light

• Uses energy from ATP (light reactions) to

reduce CO2 to sugars

• Carbon fixation

Summary

• Light H20 CO2

Photosystems & ETC

Chlorophyll a

Chemiosmosis

Calvin Cycle

NADP+

ADP+ P

ATP

NADPH

O2 sugars Cellular respiration

Organic cpds