Energy Transfer and Cellular Respiration

Study Notes

Energy Transfer and Cellular Respiration

ATP (adenosine triphosphate) stores more energy than ADP (adenosine diphosphate) due to its extra phosphate groups with negative charges.
Exergonic reactions release energy—products have less energy than reactants.
Endergonic reactions absorb energy—products have more energy than reactants. Photosynthesis is endergonic; respiration is exergonic.
The First Law of Thermodynamics: Energy cannot be created or destroyed, only transformed.
ATP is used to phosphorylate molecules like glutamic acid, converting it to ADP.
Redox reactions involve one substance losing electrons (oxidation) and another gaining electrons (reduction).
Enzymes like hexokinase catalyze specific reactions, for example, glucose phosphorylation.
Glycolysis produces 2 ATP, 2 NADH, 2 pyruvates, and 2 water molecules.
The Citric Acid Cycle (Krebs Cycle) releases CO2, involving redox reactions. This cycle occurs twice per glucose molecule.
The Electron Transport Chain (ETC) is a series of redox reactions transferring electrons in the inner mitochondrial membrane. Oxygen is the final electron acceptor, forming water.
The proton motive force is a gradient generated by H+ ions (protons) across the inner mitochondrial membrane. This gradient provides energy for ATP synthesis.
Cold temperatures can sometimes decrease cellular respiration efficiency.
Fermentation regenerates NAD+ in the absence of oxygen. Alcohol and lactic acid fermentations differ in the byproducts they create.
Oxidative Phosphorylation is the final step of cellular respiration, using the ETC and chemiosmosis to produce a large amount of ATP.
ATP synthase drives ATP production through chemiosmosis, as H+ move across the inner mitochondrial membrane.
38 ATP molecules can be produced per glucose molecule.
Locations of key processes:
- Glycolysis: Cytoplasm
- Oxidative Phosphorylation: Mitochondria
- Pyruvate oxidation and Citric Acid Cycle: Mitochondrial matrix
Inputs and outputs of different steps:
- 6O2 (oxygen) is used/produced in oxidative phosphorylation (mitochondria).
- 6CO2 (carbon dioxide) is used/produced in pyruvate oxidation and the citric acid cycle (mitochondria).
- 6H2O (water) is used/produced in Glycolysis, the citric acid cycle, and oxidative phosphorylation (cytosol, mitochondrial matrix, and mitochondria, respectively)
- 38ATP (adenosine triphosphate) is produced by oxidative phosphorylation (mitochondria).
Fermentation serves to regenerate NAD+ in the absence of oxygen.
Two CO2 molecules are produced for each acetyl CoA.

Cellular Respiration Summary

Cellular respiration is the process of extracting energy from glucose.
The process involves four key steps: glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation.

Description

Explore the key concepts of energy transfer in cellular respiration, including ATP formation, exergonic and endergonic reactions. This quiz covers fundamental topics like glycolysis, the citric acid cycle, and the role of enzymes in metabolic pathways. Test your understanding of how energy is transformed in biological systems.