Mitochondria and Cellular Respiration:
9.1 Electron Shuttles
Within the cytosol, two NADH molecules span the membrane during glycolysis.
9.2 Glycolysis
Glycolysis involves the conversion of glucose into 2 pyruvate molecules, yielding 2 ATP via substrate-level phosphorylation, and producing 2 NADH molecules.
Pyruvate Oxidation
The 2 pyruvate molecules are converted into 2 acetyl CoA molecules, which enter the citric cycle, yielding 2 ATP via substrate-level phosphorylation.
Mitochondrion and Oxidative Phosphorylation
The mitochondrion's oxidative phosphorylation includes the electron transport and chemiosmosis processes, yielding around 26-28 ATP, depending on the shuttle used for NADH electrons transport from the cytosol.
Concept Paragraph: Cellular Respiration and Energy Harvesting
Our bodies utilize catabolic pathways to break down complex molecules, releasing stored energy to produce ATP. These organic compounds store potential energy, which is released during the catabolic process known as cellular respiration. Electrons are transferred during cellular respiration, initiating redox reactions. This process involves oxidation and reduction, with the number of oxygen bonds indicating the degree of electron loss and molecule's oxidation level. The energy required to remove an electron is influenced by electronegativity and affinity, and energy must be harvested gradually to be effective. Cellular respiration stores electrons in carriers to release their energy in a controlled manner while preserving their high energy levels.
Role of Glycolysis
Glycolysis occurs in the cytoplasm, converting a glucose molecule into two 3-carbon pyruvate molecules. This process represents an initial energy investment which yields a net profit in the form of two ATP and two NADH molecules.
Definitions
- Fermentation: A catabolic process that partially degrades sugar or organic fuel without oxygen.
- Aerobic Respiration: A catabolic process that requires oxygen.
- Redox Reactions: The transfer of electrons between reactants.
- Oxidation & Reduction: The loss and gain of electrons, respectively.
- NAD+ & NADH: Electron acceptor and reduced form during respiration.
- Glycolysis: Breaks down glucose into pyruvate in the cytosol.
- Pyruvate Oxidation: The conversion of pyruvate to acetyl-CoA in the mitochondria.
- The Citric Acid Cycle: Completes the breakdown of glucose.
- Oxidative Phosphorylation: Generates ATP through the electron transport chain and chemiosmosis.
- Substrate-level Phosphorylation: Produces ATP in glycolysis and the citric acid cycle.
Citric Acid Cycle and Oxidative Processes
The citric acid cycle completes the glucose breakdown, producing NADH and FADH2, while the oxidative phosphorylation in the mitochondrion results in a high yield of ATP through the electron transport chain and chemiosmosis.
Conclusion
The processes of cellular respiration and fermentation are vital in energy production at the cellular level, and understanding their intricacies is crucial for comprehending the chemical reactions that sustain life. This knowledge can be applied to various fields such as biology, biochemistry, and food science.
For further learning, questions like: "what is the role of mitochondria in cellular respiration?" and "successfully making cheese requires separating what?" can be explored by referring to resources like 'Cellular Respiration and Fermentation worksheet', 'Chapter 9 Mastering Biology answers', 'Mitochondria and Cellular Respiration worksheet', and 'Drag the labels to place the steps of glycolysis in the correct sequence.' These resources facilitate a deeper understanding of the complex processes underlying energy generation in living organisms.
