Recording-2025-03-24T20:00:48.152Z

Glycolysis

• Starts with a six-carbon glucose compound.

• Splits into two three-carbon pyruvate molecules.

• Produces ATP, precursor metabolites, and NADH (reducing power).

• Key processes: energy production and metabolite generation for anabolic reactions.

Pentose Phosphate Pathway

• Another route for glucose breakdown.

• Focuses on providing metabolites necessary for biosynthesis (anabolism).

• Produces ATP, precursor metabolites, and reducing power, similar to glycolysis.

• Essential for cellular metabolism across different organisms.

TCA Cycle (Krebs Cycle)

• Further breakdown of metabolites generated in glycolysis.

• Generates more reducing power and ATP, setting up for the next major pathway in cellular respiration.

Cellular Respiration

• Electrons collected from glycolysis and TCA cycle enter the Electron Transport Chain (ETC).

• Oxidative Phosphorylation occurs in the membrane (mitochondrial in eukaryotes, cell membrane in prokaryotes).

• Aerobic Respiration: uses oxygen as the final electron acceptor, yielding the highest ATP production (up to 38 ATP per glucose).

• Anaerobic Respiration: use of alternatives to oxygen, usually yields less ATP than aerobic.

• Fermentation: occurs in absence of oxygen, even in facultative anaerobes like E. coli, generating ATP but less efficiently than respiration.

ATP Production Efficiency

• Greatest ATP yield from aerobic respiration.

• Anaerobic respiration and fermentation yield less ATP but allow survival without oxygen.

• Microorganisms adapt to various environments using different metabolic pathways to ensure ATP production.

Role of Enzymes

• Enzymes are critical for metabolic pathways: they catalyze reactions and increase the rate by lowering activation energy.

• Enzymes are not consumed or permanently altered in reactions; they repeatedly function.

• Active sites are specific for substrates; the binding leads to the product formation without altering the enzyme.

• Enzymes require cofactors (e.g., minerals) and coenzymes (organic compounds) to assist in the chemical reactions.

Enzyme Regulation

• Enzymes can be regulated through feedback inhibition where the end product inhibits the enzyme when in excess.

• Allosteric Sites: binding at these sites can modify the active site, either enhancing or inhibiting enzyme activity.

• Competitive Inhibition: an inhibitor competes with the substrate for the active site.

• Non-competitive Inhibition: an inhibitor binds to an allosteric site, altering enzyme structure, and thus preventing substrate binding.

Importance of Homeostasis

• Maintaining proper pH, temperature, and salt concentration is crucial for enzyme activity.

• Denaturation of enzymes can lead to loss of function, reducing metabolic efficiency.

Feedback Mechanisms

• Metabolic pathways are tightly regulated by feedback mechanisms where the accumulation of end products can inhibit the pathway to conserve resources.

• Enzymes and their regulation ensure that cells only produce what is necessary for vital functions.