Question

Identify an example organism for each type of cellular respiration: aerobic respiration, anaerobic respiration, and fermentation. Specifically identify the steps used by that organism to generate energy, including the final electron accepter.

Answer 1

Answer:

Anaerobic respiration-" The process by which cells that do not breathe oxygen liberate energy from fuel to power their life functions."

• These organisms also use an electron transport chain to generate as much ATP as possible from their fuel, but their electron transport chains extract less energy than those of aerobic respiration because their electron acceptors are weaker. The Staphylococcus aureus and Lactococcus lactis are two organism which performs anaerobic respiration.

• Aerobic respiration-"The process by which oxygen-breathing creatures turn fuel, such as fats and sugars, into energy."

Organisms who performs aerobic respiration:

Most of the living beings humans etc.

Fermentation:"The metabolic process by which organic molecules (normally glucose) are converted into acids, gases, or alcohol in the absence of oxygen or any electron transport chain."

Mechanism-" The main porpuse is to convert NADH back into the coenzyme NAD⁺ so that it can be used again for glycolysis."

• During fermentation, an organic electron acceptor  reacts with NADH to form NAD⁺, generating products such as carbon dioxide and ethanol or lactate in the process.

Types-

1. Ethanol fermentation,
2. Lactic acid fermentation.

Explanation:

Difference between Aerobic and anaerobic respiration:

• In anaerobic cells, however, respiration typically takes place in the cell’s cytoplasm, since most anaerobic cells do not have specialized organelles.
• In aerobic cells, the electron transport chain, and most of the chemical reactions of respiration, occur in the mitochondria.

Steps of Aerobic Respiration:

1. Glycolysis. In aerobic cells, the equation for glycolysis is:

• Glucose + 2 HPO₄²⁻- + 2 ADP³⁻ + 2 NAD⁺ → 2 Pyruvate⁻ + 2 ATP⁴⁻-+ 2 NADH + 2 H⁺ + 2 H₂O,

2. Oxidative decarboxylation of pyruvate

• 2 (Pyruvate⁻ + Coenzyme A + NAD⁺ → Acetyl CoA + CO₂ + NADH),

3. Citric acid cycle

2 (Acetyl CoA + 3 NAD⁺ + FAD + GDP³⁻ + HPO₄²⁻ + 2H₂O → 2 CO₂ + 3 NADH + FADH₂ + GTP⁴⁻ + 2H⁺ + Coenzyme A),

4. Oxidative phosphorylation

34 (ADP³⁻ + HPO₄²⁻ + NADH + 1/2 O₂ + 2H+ → ATP⁴⁻ + NAD⁺ + 2 H₂O)

• Electron Transport Chain Steps- These four complexes actively transfer electrons from an organic metabolite, such as glucose. When the metabolite breaks down, two electrons and a hydrogen ion are released and then picked up by the co-enzyme NAD+ to become NADH, releasing a hydrogen ion into the cytosol.

1. Complex I: The complex-structured proteins embedded in the phospho-lipid membrane.
2. Continuing onto Complex II,
3. Traversed to Complex III,
4. Cytochrome c via co-enzyme Q,
5. And then finally to Complex IV.

Note-By-products from other cycles and processes, like the citric acid cycle, amino acid oxidation, and fatty acid oxidation, are used in the electron transport chain. As seen in the overall redox reaction,

• 2 H+ + 2 e+ + ½ O₂ → H₂O + energy