Cellular Respiration and Fermentation Overview Chapter 9

What is the primary function of cellular respiration?

To use electrons from high-energy molecules to make ATP.

What are the two fundamental requirements of cells for cellular respiration?

Energy to generate ATP and a source of carbon for synthesizing macromolecules.

What is the process by which glucose is broken down into pyruvate?

Glycolysis.

What is produced during glycolysis?

Two NADH, two ATP, and two pyruvate.

What happens to pyruvate during pyruvate processing?

Each pyruvate is oxidized to form acetyl CoA.

What is the outcome of the citric acid cycle?

Each acetyl CoA is oxidized to CO2.

What is the role of the electron transport chain in cellular respiration?

Electrons move through a transport chain, setting up a proton gradient used to make ATP.

What is the significance of ATP in cellular activities?

ATP provides energy for cellular processes.

How do cells obtain glucose for ATP production?

Plants produce glucose during photosynthesis; other organisms obtain it from food.

What are catabolic pathways?

Destructive metabolism that breaks down molecules for ATP production.

What types of molecules can furnish substrates for cellular respiration?

Proteins, carbohydrates, and fats.

What is feedback inhibition in glycolysis?

High levels of ATP inhibit the enzyme phosphofructokinase, regulating glycolysis.

Where does glycolysis occur in eukaryotic and prokaryotic cells?

In the cytosol.

What is the net yield of ATP during glycolysis?

Two ATP.

What is the chemical formula for glucose?

C6H12O6.

What are the products of pyruvate processing?

Acetyl CoA and CO2.

What is the role of NADH in cellular respiration?

NADH carries electrons to the electron transport chain.

What is the main purpose of the citric acid cycle?

To oxidize acetyl CoA to CO2 and produce electron carriers.

What is the significance of maintaining homeostasis in metabolism?

It allows the organism to maintain a stable internal environment despite external changes.

What is oxidative phosphorylation?

The process where the energy from electrons is used to produce ATP via a proton gradient.

What is the role of ATP in the energy investment phase of glycolysis?

Two ATP are used to initiate the breakdown of glucose.

What is the meaning of 'glycolysis'?

The term 'glycolysis' means 'sugar splitting'.

Where does glycolysis occur in eukaryotes and prokaryotes?

In the cytosol of eukaryotes and prokaryotes.

What is the role of pyruvate dehydrogenase in pyruvate processing?

It is an enzyme complex that processes pyruvate into acetyl CoA.

Where is pyruvate dehydrogenase located in eukaryotes and prokaryotes?

In the mitochondrial matrix in eukaryotes and in the cytosol in prokaryotes.

What are the main products of pyruvate processing?

Acetyl CoA, NADH, and CO2.

What happens to one of the carbons during pyruvate processing?

It is oxidized to CO2.

What is the significance of feedback inhibition in pyruvate processing?

It regulates pyruvate dehydrogenase activity when products are abundant.

What is the main function of acetyl CoA in cellular respiration?

It enters the Citric Acid Cycle.

Where does the Citric Acid Cycle occur in eukaryotes and prokaryotes?

In the mitochondrial matrix in eukaryotes and in the cytosol in prokaryotes.

What are the main outputs of the Citric Acid Cycle for each glucose molecule?

6 NADH, 2 FADH2, and 2 ATP.

How many times does the Citric Acid Cycle turn for each glucose molecule?

Twice, since two pyruvate are produced from one glucose.

What is produced from the oxidation of acetyl CoA in the Citric Acid Cycle?

Two CO2 molecules.

What are the three main energy-storing molecules produced during cellular respiration?

ATP, NADH, and FADH2.

How is the Citric Acid Cycle regulated?

It is regulated by feedback inhibition, particularly by ATP and NADH levels.

What is the waste bi-product of the Citric Acid Cycle?

CO2.

What happens to the reduced electron carriers NADH and FADH2 after the Citric Acid Cycle?

They are used in the electron transport chain to produce ATP.

What are the two main phases of glycolysis?

Energy investment phase and energy payoff phase.

What is the chemical formula for pyruvate?

C3H4O3.

What is the role of coenzyme A in pyruvate processing?

It attaches to the remaining two-carbon unit to form acetyl CoA.

What is the significance of the cristae in mitochondria?

They increase the surface area for biochemical reactions.

What is the intermembrane space in mitochondria?

The space between the inner and outer mitochondrial membranes.

What is the function of NAD+ in cellular respiration?

It acts as an electron carrier, being reduced to NADH.

What is the role of NADH and FADH2 in cellular respiration?

They transfer electrons to the electron transport chain (ETC), where most of glucose's original energy is stored.

What is the final electron acceptor in the electron transport chain?

Oxygen, which combines with protons to form water.

What is the function of the electron transport chain (ETC)?

The ETC oxidizes NADH and FADH2, transferring electrons through a series of proteins and generating a proton gradient.

What is ubiquinone, and what is its role in the ETC?

Ubiquinone, also known as coenzyme Q, is a lipid-soluble non-protein that transfers electrons between complexes in the ETC.

How is ATP synthesized during oxidative phosphorylation?

ATP is produced as protons move through ATP synthase, driven by the proton-motive force generated by the electrochemical gradient.

What distinguishes oxidative phosphorylation from substrate-level phosphorylation?

Oxidative phosphorylation occurs during the electron transport chain, while substrate-level phosphorylation occurs during glycolysis and the citric acid cycle.

What happens to NADH when there is no electron acceptor available?

NADH builds up, and there is no NAD+ available, causing glycolysis, pyruvate processing, and the citric acid cycle to stop.

What is fermentation, and why is it important?

Fermentation is a metabolic pathway that regenerates NAD+ from NADH, allowing glycolysis to continue producing ATP in the absence of oxygen.

What occurs during lactic acid fermentation in muscle cells?

Pyruvate accepts electrons from NADH, producing lactate and regenerating NAD+.

What is the end product of alcohol fermentation in yeast?

Ethanol and carbon dioxide are produced when acetaldehyde accepts electrons from NADH.

How many ATP are produced from one glucose molecule during fermentation?

2 ATP are produced per glucose during fermentation.

What is the ATP yield from cellular respiration compared to fermentation?

Cellular respiration yields about 29 ATP per glucose, while fermentation yields only 2 ATP.

What are facultative anaerobes?

Organisms that can switch between fermentation and aerobic respiration depending on the availability of an electron acceptor.

What is the proton-motive force?

The proton-motive force is the electrochemical gradient of protons across the mitochondrial membrane that drives ATP synthesis.

What is chemiosmosis?

Chemiosmosis is the process by which ATP is produced using the energy from the proton gradient.

What are the four protein complexes in the electron transport chain?

Complexes I, II, III, and IV.

What happens to electrons as they move through the ETC?

They are held more tightly, releasing a small amount of energy at each reaction.

What is the significance of redox potential in the ETC?

It refers to the differential ability of molecules to accept electrons, influencing their role in the electron transport chain.

What is produced at the end of the electron transport chain?

Water is formed when low-energy electrons are passed to oxygen along with protons.

What is the role of ATP synthase?

ATP synthase is the enzyme that synthesizes ATP from ADP and inorganic phosphate (Pi) using the energy from protons moving through it.

What is the relationship between the ETC and ATP production?

The ETC generates a proton gradient that is essential for ATP production through chemiosmosis.

What metabolic pathways can occur in the absence of oxygen?

Fermentation pathways, such as lactic acid fermentation and alcohol fermentation.

What is the emergency backup pathway for ATP production when oxygen is scarce?

Fermentation, which allows glycolysis to continue by regenerating NAD+.