bio exam 1

What is fermentation and when does it occur?

Fermentation is a metabolic process that occurs in the absence of oxygen (anaerobic conditions), allowing organisms to convert sugars into energy, typically resulting in byproducts like alcohol or organic acids.

What are the end products of fermentation in animals and yeast?

In animals, the end product of fermentation is lactate. In yeast, fermentation produces ethanol (alcohol) and carbon dioxide (CO₂), which is used in brewing and baking.

Why is fermentation considered inefficient?

Fermentation is considered inefficient because it only converts about 7% of the energy contained in glucose into usable ATP, whereas aerobic processes are more productive.

What is a primary reason aerobic respiration is more efficient than fermentation?

Aerobic respiration is more efficient than fermentation because it fully oxidizes glucose, extracting much more energy and yielding up to 38 ATP molecules from a single glucose molecule.

What role does oxygen play in aerobic respiration?

In aerobic respiration, oxygen acts as the final electron acceptor in the electron transport chain, facilitating the production of ATP through oxidative phosphorylation.

Where does the citric acid cycle take place?

The citric acid cycle, also known as the Krebs cycle or tricarboxylic acid cycle (TCA), occurs in the mitochondrial matrix, where acetyl-CoA is processed to produce energy carriers.

What are the main products of the citric acid cycle?

The main products of the citric acid cycle include NADH and FADH₂ (electron carriers), carbon dioxide (CO₂) as a waste product, and a small quantity of ATP or GTP.

What enzyme converts pyruvate into acetyl-CoA?

The enzyme responsible for converting pyruvate into acetyl-CoA is called pyruvate dehydrogenase, which also releases CO₂ during the process.

Which mitochondrial compartment contains the enzymes for the citric acid cycle?

The mitochondrial matrix houses the enzymes necessary for the citric acid cycle, allowing for the processing of acetyl-CoA into energy.

How does ATP synthase generate ATP?

ATP synthase generates ATP by harnessing the energy from a proton gradient across the mitochondrial membrane, using the flow of protons to drive the conversion of ADP and inorganic phosphate into ATP.

What regulates the citric acid cycle?

The citric acid cycle is primarily regulated by the levels of ATP, NADH, and other metabolites, which indicate the energy needs of the cell.

What process breaks down fatty acids into acetyl-CoA?

Beta-oxidation is the metabolic process that breaks down fatty acids into acetyl-CoA units, which can then enter the citric acid cycle for energy production.

Why is protein catabolism considered a last resort for energy production?

Protein catabolism is viewed as a last resort for energy production because it degrades muscle and tissue proteins for energy, typically occurring only during prolonged starvation or intense exercise.

Which molecule serves as the final electron acceptor in the electron transport chain (ETC)?

Oxygen functions as the final electron acceptor in the electron transport chain, allowing electrons to combine with protons to form water, which is crucial for maintaining the flow of electrons.

What is the function of cristae in mitochondria?

Cristae are the inner membrane folds of mitochondria that increase the surface area available for ATP production; they contain essential components of the electron transport chain and ATP synthase.

What energy currency is primarily produced by oxidative phosphorylation?

ATP (adenosine triphosphate) is the primary energy currency produced through the process of oxidative phosphorylation during cellular respiration.

What are the major electron carriers in the electron transport chain?

The major electron carriers in the electron transport chain are NADH and FADH₂, which transport electrons from metabolic pathways to the ETC, driving ATP production.

What is the role of ATP in cellular processes?

ATP acts as the main energy currency of the cell, powering various biochemical reactions, including biosynthesis, movement, and active transport across cell membranes.

What happens to NADH and FADH₂ in the electron transport chain?

In the electron transport chain, NADH and FADH₂ are oxidized, releasing electrons that are transferred through a series of protein complexes, ultimately leading to ATP synthesis and water formation.

How does the proton gradient across the mitochondrial membrane contribute to ATP synthesis?

The proton gradient created by the movement of protons across the mitochondrial membrane stores potential energy due to the concentration difference, which ATP synthase utilizes to phosphorylate ADP into ATP.

What is the importance of the mitochondrial membrane potentials in energy production?

The mitochondrial membrane potential is critical for energy production; it generates the electrochemical gradient necessary for ATP synthesis and also governs the transport of metabolites.

Define oxidative phosphorylation in cellular respiration.

Oxidative phosphorylation is the final stage of cellular respiration, occurring in the mitochondria, where energy from electrons transferred through the electron transport chain is used to synthesize ATP.

What are the three main stages of cellular respiration?

The three main stages of cellular respiration are glycolysis (breaking down glucose), the citric acid cycle (oxidizing acetyl-CoA), and oxidative phosphorylation (producing ATP via the electron transport chain).

What is the significance of anaerobic respiration?

Anaerobic respiration allows organisms to produce energy in the absence of oxygen, enabling survival in low-oxygen environments and contributing to various biological processes like fermentation.