(Biology 150) Chapter 9 - Cellular Respiration and Fermentation

What do living cells require for energy?

Energy from outside sources, such as food.

What is the primary function of photosynthesis in an ecosystem?

To convert light energy into organic molecules and release oxygen.

What is the role of ATP in cellular processes?

ATP powers most cellular work by storing and providing energy.

What are catabolic pathways?

Pathways that release stored energy by breaking down complex molecules.

What is fermentation?

A partial degradation of sugars that occurs without oxygen.

What is aerobic respiration?

A process that consumes organic molecules and oxygen to yield ATP.

What is anaerobic respiration?

Similar to aerobic respiration but consumes compounds other than oxygen.

What is the chemical equation for cellular respiration using glucose?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (ATP + heat).

What are redox reactions?

Chemical reactions that transfer electrons between reactants.

What happens during oxidation?

A substance loses electrons.

What happens during reduction?

A substance gains electrons.

What is the reducing agent in a redox reaction?

The electron donor that becomes oxidized.

What is the oxidizing agent in a redox reaction?

The electron receptor that becomes reduced.

What is the role of NAD+ in cellular respiration?

NAD+ acts as an oxidizing agent and electron acceptor.

What does NADH represent in cellular respiration?

Stored energy that is used to synthesize ATP.

What is the electron transport chain?

A series of steps where electrons are passed to yield energy for ATP synthesis.

What are the three stages of cellular respiration?

Glycolysis, the citric acid cycle, and oxidative phosphorylation.

What is glycolysis?

The process that breaks down glucose into two molecules of pyruvate.

What is the citric acid cycle?

The stage that completes the breakdown of glucose.

What is oxidative phosphorylation?

The process that generates most ATP, powered by redox reactions.

How much ATP can be generated from one molecule of glucose during respiration?

Up to 32 molecules of ATP.

What is substrate-level phosphorylation?

A process that generates ATP during glycolysis and the citric acid cycle.

What is the main energy source for cellular respiration?

Organic molecules, primarily glucose.

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

It allows for a controlled release of energy to regenerate ATP.

What is the relationship between cellular respiration and heat energy?

Cellular respiration releases heat energy as a byproduct.

What is the role of oxygen in aerobic respiration?

Oxygen acts as the final electron acceptor in the electron transport chain.

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration uses oxygen, while anaerobic respiration does not.

What is the outcome of the oxidation of organic fuel molecules during cellular respiration?

The fuel is oxidized, and oxygen is reduced.

What are the two major phases of glycolysis?

Energy investment phase and energy payoff phase.

Does glycolysis require oxygen?

No, glycolysis occurs whether or not O2 is present.

What is the net gain of ATP from glycolysis?

2 ATP (4 ATP formed - 2 ATP used).

What are the products of glycolysis?

2 pyruvate, 2 NADH, and 2 ATP.

What happens to pyruvate in the presence of oxygen?

Pyruvate enters the mitochondrion where it is converted to acetyl CoA.

What is the citric acid cycle also known as?

The Krebs cycle.

What does the citric acid cycle produce per turn?

1 ATP, 3 NADH, and 1 FADH2.

How many steps are there in the citric acid cycle?

Eight steps, each catalyzed by a specific enzyme.

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

They relay electrons extracted from food to the electron transport chain.

Where is the electron transport chain located?

In the inner membrane (cristae) of the mitochondrion.

What is chemiosmosis?

The use of energy in a H+ gradient to drive cellular work, specifically ATP synthesis.

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

Oxygen, which forms water (H2O) when it accepts electrons.

What is the function of ATP synthase?

To use the exergonic flow of H+ to drive phosphorylation of ATP.

What is the significance of the proton-motive force?

It is the force that drives protons back across the membrane, powering ATP synthesis.

What is the first step of the citric acid cycle?

The acetyl group of acetyl CoA combines with oxaloacetate to form citrate.

What is produced during the conversion of pyruvate to acetyl CoA?

NADH and CO2 are produced.

What is the role of the pyruvate dehydrogenase complex?

It catalyzes the conversion of pyruvate to acetyl CoA.

What is the energy yield of glycolysis in terms of NADH?

2 NADH are produced during glycolysis.

What is the role of isomerase in glycolysis?

To convert glucose-6-phosphate to fructose-6-phosphate.

What does the term 'energy investment phase' refer to in glycolysis?

The phase where ATP is used to phosphorylate glucose and its derivatives.

What is the significance of the high-energy enol-P linkage?

It is formed during glycolysis and is crucial for ATP production.

What happens during the energy payoff phase of glycolysis?

ATP and NADH are produced from the conversion of glyceraldehyde 3-phosphate.

What is the main purpose of the citric acid cycle?

To complete the breakdown of pyruvate to CO2 and generate electron carriers.

What is produced when electrons are transferred to O2 in the electron transport chain?

Water (H2O) is produced.

What is the process called that synthesizes ATP through the addition of a phosphate group to ADP?

Oxidative phosphorylation

What is the role of the H+ gradient in ATP synthesis?

It drives the synthesis of ATP by coupling redox reactions of the electron transport chain.

What is the maximum amount of ATP produced per glucose molecule during cellular respiration?

About 30 to 32 ATP

What happens to the electron transport chain without oxygen?

It ceases to operate.

What are the two common types of fermentation?

Alcohol fermentation and lactic acid fermentation.

What is produced during alcohol fermentation?

Ethanol and carbon dioxide.

What is the end product of lactic acid fermentation?

Lactate.

What is the primary function of glycolysis?

To oxidize glucose and harvest chemical energy.

What is the role of NAD+ in glycolysis?

It acts as the oxidizing agent that accepts electrons.

What are obligate anaerobes?

Organisms that carry out fermentation or anaerobic respiration and cannot survive in the presence of oxygen.

What is the significance of glycolysis in evolutionary terms?

It is thought to have been used by ancient prokaryotes before oxygen was present in the atmosphere.

What is the process by which fatty acids are broken down to generate acetyl CoA?

Beta oxidation.

How do proteins contribute to cellular respiration?

They must be digested to amino acids, which can feed into glycolysis or the citric acid cycle.

What is feedback inhibition in the context of cellular respiration?

A mechanism where ATP concentration regulates the speed of respiration.

What is the proton-motive force?

The H+ gradient across a membrane that has the capacity to do work.

What is the net ATP yield from glycolysis?

2 ATP.

What is the role of fermentation in the absence of oxygen?

It allows glycolysis to continue by regenerating NAD+.

What are facultative anaerobes?

Organisms that can survive using either fermentation or cellular respiration.

What is the primary electron carrier in cellular respiration?

NADH.

What is produced during the citric acid cycle?

NADH, FADH2, ATP, and CO2.

What is the main function of the electron transport chain?

To transfer electrons and pump protons to create a gradient for ATP synthesis.

What is the role of ATP synthase in oxidative phosphorylation?

It synthesizes ATP from ADP and inorganic phosphate using the energy from the proton gradient.

What is the relationship between glycolysis and the citric acid cycle?

They are major intersections for various catabolic and anabolic pathways.

What is the final electron acceptor in aerobic respiration?

Oxygen (O2).

What is the process of converting pyruvate to ethanol in fermentation?

Alcohol fermentation.

What is the process of converting pyruvate to lactate in fermentation?

Lactic acid fermentation.