Cellular Respiration: Pathways and Processes Section 6: Fermentation & Anaerobic Alternatives

Hibernation Adaptation

Lowered metabolism in mammals conserving energy during winter.

Chloroplast Chemiosmosis

Light-driven ATP synthesis in plant cells.

Fermentation

Anaerobic process breaking down sugars without oxygen.

Anaerobic process

Metabolic process occurring without the presence of oxygen.

ATP production without oxygen or electron transport chain

Energy generation in the absence of O2, using substrate-level phosphorylation.

Alcohol Fermentation

Anaerobic conversion of pyruvate to ethanol, releasing CO2 and regenerating NAD+.

Lactic Acid Fermentation

Anaerobic conversion of pyruvate to lactate, regenerating NAD+.

NAD+

Coenzyme recycled for glycolysis continuation during anaerobic fermentation.

NADH

Electron carrier donates electrons, reducing pyruvate and regenerating NAD+.

Pyruvate

Glycolysis end product used in fermentation and gluconeogenesis processes.

Acetaldehyde

Intermediate in alcohol fermentation, reduced to ethanol.

Lactate

End product of lactic acid fermentation.

Sulfate-Reducing Bacteria

Microorganisms that use sulfate as the final electron acceptor in anaerobic respiration.

Hydrogen Sulfide (H2S)

Product of sulfate reduction during anaerobic respiration.

Strenuous Exercise

Oxygen limitation in muscles causes lactate production via fermentation.

Potassium Ions (K+)

Ions imbalance affects muscle function and fatigue, contrasting with lactate accumulation effects.

Liver Metabolism

Lactate is converted to pyruvate or glucose (Cori cycle).

Comparison of Pathway

ATP yield differences in fermentation: anaerobic vs. aerobic.

Obligate Anaerobes

Organisms that cannot survive in the presence of oxygen

Facultative Anaerobes

Organisms switch between aerobic respiration and fermentation/anaerobic respiration based on oxygen availability.

Anaerobic Respiration

ATP generation via electron transport chain, excluding oxygen as acceptor.

Sulfate as final electron acceptor

Molecule replaces oxygen in anaerobic bacteria's electron transport chain.

Final electron acceptor

Substrate accepting electrons in anaerobic respiration, like sulfate.

Cyanobacteria

Photosynthetic bacteria released oxygen, enabling aerobic respiration evolution.

Evolutionary Basis of Glycolysis

Different metabolic routes connect carbohydrate, protein, and fat metabolism.

Metabolic Pathways Interconnection

Different metabolic routes connect carbohydrate, protein, and fat metabolism.

Deamination

Amino group removal enables amino acid conversion for respiration.

Nitrogenous Waste

Ammonia, urea, or uric acid from deamination process.

Carbon Skeletons

Carbon chains from broken amino acids or fats enter glycolysis or citric acid cycle.

Catabolism

Metabolic pathways degrade complex molecules, releasing energy during fermentation.

Beta Oxidation

Fatty acids convert to acetyl CoA, entering the citric acid cycle, alternative to glucose metabolism.

ATP Yield

Fermentation produces 2 ATP anaerobically; aerobic processes yield more ATP using oxygen, highlighting differences in energy production methods.

Anabolic Pathways

Anabolism builds complex molecules, consuming energy, unlike catabolism.

Essential Amino Acids

Essential amino acids, required from diet, affect metabolic fuel availability for respiration.

Feedback Inhibition

End product inhibits earlier step, controlling respiration and fermentation rates.

Phosphofructokinase

ATP and citrate regulate glycolysis, linking glucose breakdown to energy.

Allosteric Enzyme

Enzymes regulated by non-active site binding control metabolic pathways and are crucial for metabolic flow.

Citrate

Intermediate inhibits phosphofructokinase, connecting glycolysis and the citric acid cycle.

Metabolic Interchanges

Cells convert molecules, impacting respiration's fuel sources and efficiency.

Glyceraldehyde-3-Phosphate

Intermediate of glycolysis linked to various other metabolic pathways.

Energy Flow

Metabolism involves energy movement and transformation through biochemical reactions in organisms.

Metabolic Balance

The maintenance of homeostasis in metabolic processes, ensuring energy supply meets demand.

Ecosystem Cycling (role of respiration)

The role of decomposition and respiration in returning carbon to the atmosphere and nutrients to the soil