CELLULAR RESPIRATION

What is the primary product of glycolysis?

2 pyruvate molecules, along with a net gain of 2 ATP and 2 NADH.

Where does glycolysis occur?

In the cytoplasm of the cell.

What enzyme catalyzes the first step of glycolysis?

Hexokinase.

Which molecule is produced during pyruvate oxidation?

Acetyl-CoA, along with CO₂ and NADH.

What are the main reactants in the Krebs cycle?

Acetyl-CoA and oxaloacetate.

What are the end products of one turn of the Krebs cycle?

3 NADH, 1 FADH₂, 1 ATP, and 2 CO₂.

What role does oxygen play in aerobic respiration?

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

What happens during anaerobic respiration?

Glucose is partially broken down into energy, producing byproducts like lactic acid or ethanol and CO₂.

What is produced during lactic acid fermentation?

Lactic acid and 2 ATP per glucose molecule.

How many ATP are produced from one molecule of glucose during aerobic respiration?

32-38 ATP.

What is the role of NAD⁺ in respiration?

NAD⁺ acts as an electron carrier, accepting electrons in glycolysis and being regenerated in fermentation.

Why is anaerobic respiration less efficient than aerobic respiration?

Anaerobic respiration only yields 2 ATP per glucose molecule, while aerobic respiration can yield 32-38 ATP.

What is the function of the electron transport chain?

To transfer electrons from NADH and FADH₂ to oxygen, creating a proton gradient that drives ATP synthesis.

What occurs in the electron transport chain?

Electrons are passed through a series of protein complexes, pumping protons across the inner mitochondrial membrane.

What are the byproducts of aerobic respiration?

Carbon dioxide (CO₂) and water (H₂O).

What is fermentation?

A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen.

What are the two types of fermentation?

Lactic acid fermentation and alcoholic fermentation.

What is produced during alcoholic fermentation?

Ethanol and CO₂, along with 2 ATP per glucose molecule.

What is the role of FAD in respiration?

FAD serves as an electron carrier, similar to NAD⁺, accepting electrons during the Krebs cycle.

What is the significance of the Krebs cycle?

It generates electron carriers (NADH and FADH₂) for the electron transport chain and produces CO₂ as a waste product.

How many times does the Krebs cycle turn per glucose molecule?

Twice, since each glucose molecule produces two acetyl-CoA.

What is oxidative phosphorylation?

The process of ATP production that occurs due to the transfer of electrons along the electron transport chain and the creation of a proton gradient.

What is the final product of cellular respiration?

ATP, along with CO₂ and H₂O as byproducts.

What is substrate-level phosphorylation?

A direct way of synthesizing ATP, occurring in glycolysis and the Krebs cycle, where a phosphate group is transferred from a substrate to ADP.

What is the function of ATP synthase?

To synthesize ATP from ADP and inorganic phosphate, using the proton gradient created by the electron transport chain.

What is the role of coenzymes in metabolic processes?

Coenzymes, such as NAD⁺ and FAD, assist in transferring electrons during enzymatic reactions.

What are the three stages of cellular respiration?

Glycolysis, the Krebs cycle, and oxidative phosphorylation.

What is the purpose of fermentation in anaerobic conditions?

To regenerate NAD⁺ allowing glycolysis to continue producing ATP in the absence of oxygen.

What type of organisms primarily utilize alcoholic fermentation?

Yeasts and some types of bacteria.

How does pyruvate enter the Krebs cycle?

Pyruvate is converted into acetyl-CoA in the mitochondria before entering the Krebs cycle.

What is the main purpose of glycolysis?

To break down glucose into pyruvate, producing ATP and NADH.

What happens to pyruvate in the presence of oxygen?

Pyruvate is converted into acetyl-CoA and enters the Krebs cycle.

What is the overall equation for cellular respiration?

Glucose + O₂ → CO₂ + H₂O + ATP.

What are NADH and FADH₂ primarily used for?

To carry electrons to the electron transport chain.

What is the role of oxygen in the electron transport chain?

Oxygen receives electrons and combines with protons to form water.

What is chemiosmosis in cellular respiration?

The process of using the proton gradient to produce ATP via ATP synthase.

How does the structure of mitochondria facilitate cellular respiration?

Mitochondria have inner membranes that create a proton gradient and contain the enzymes for the Krebs cycle and electron transport chain.

What is the significance of the electron transport chain?

It produces the majority of ATP during cellular respiration.

What is the role of proton pumps in the electron transport chain?

To actively transport protons across the mitochondrial membrane, establishing a proton gradient.

How is carbon dioxide produced during cellular respiration?

CO₂ is produced as a byproduct during the conversion of pyruvate to acetyl-CoA and in the Krebs cycle.

What is the purpose of cellular respiration?

To convert biochemical energy from nutrients into ATP, which cells use for energy.

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration requires oxygen and produces more ATP, while anaerobic respiration occurs without oxygen and produces less ATP.

What is ATP made up of?

Adenine, ribose (a sugar), and three phosphate groups.

What is the role of glucose in cellular respiration?

Glucose serves as the primary energy source that is broken down to produce ATP.

What happens during oxidative phosphorylation?

Electrons are transferred through the electron transport chain, driving ATP production and resulting in water formation.

What is the key regulatory enzyme in glycolysis?

Phosphofructokinase (PFK), which controls the rate of glycolysis.

What are the two phases of glycolysis?

The energy-investment phase and the energy-generation phase.

How does fermentation enable cells to generate ATP?

By regenerating NAD⁺, allowing glycolysis to continue in the absence of oxygen.

What is the significance of the proton gradient in cellular respiration?

It is used by ATP synthase to produce ATP during chemiosmosis.

What is the function of coenzyme A in cellular respiration?

To transport acetyl groups into the Krebs cycle for energy production.

What molecule enters the Krebs cycle to initiate the process?

Acetyl-CoA.

What is substrate-level phosphorylation?

The generation of ATP through the direct transfer of a phosphate group from a substrate to ADP.

How does ATP serve as an energy currency in cells?

ATP stores and releases energy as needed for cellular processes.

What is the primary electron donor in the electron transport chain?

NADH and FADH₂ donate electrons to the electron transport chain.

In what part of the mitochondria does the Krebs cycle occur?

In the mitochondrial matrix.

How are fats metabolized in cellular respiration?

Fats are broken down into fatty acids and glycerol, which can be converted into acetyl-CoA.

What is the role of uncoupling proteins in cellular respiration?

They dissipate the proton gradient in mitochondria, generating heat instead of ATP.

What is the role of glucose in glycolysis?

Glucose is broken down into two pyruvate molecules, generating ATP and NADH in the process.

What happens to acetyl-CoA in the Krebs cycle?

Acetyl-CoA enters the Krebs cycle and combines with oxaloacetate to form citrate, starting the cycle.

What is the impact of oxygen deprivation on cellular respiration?

Oxygen deprivation leads to anaerobic respiration, reducing ATP production and generating lactic acid or ethanol.

How do protons contribute to ATP production?

Protons flow back into the mitochondrial matrix through ATP synthase, driving the synthesis of ATP.

What is the role of the mitochondrial inner membrane in respiration?

It hosts the proteins and enzymes necessary for the electron transport chain and ATP synthesis.

What triggers the production of more ATP in response to a high ADP concentration?

A high concentration of ADP signals the need for more ATP production, stimulating the pathways of cellular respiration.

How does temperature affect cellular respiration?

Temperature affects enzyme activity, with higher temperatures generally increasing the rate of respiration up to an optimal point.

In which organisms does fermentation occur?

Fermentation occurs in anaerobic organisms like yeasts and certain bacteria.

What are the benefits of fermentation?

Fermentation allows ATP production in the absence of oxygen and regenerates NAD⁺ for glycolysis to continue.

What type of relationship exists between aerobic and anaerobic respiration?

They are alternative metabolic pathways for ATP production, with aerobic respiration being more efficient.

What is glycolysis?

A metabolic process that breaks down glucose into pyruvate, producing ATP and NADH.

What are the main stages of oxidative phosphorylation?

Electron transport chain and chemiosmosis.

What is the function of oxygen in aerobic respiration?

Oxygen is essential as the final electron acceptor, allowing the electron transport chain to function.

What are the two main types of cellular respiration?

Aerobic and anaerobic respiration.

What is generated during the energy-investment phase of glycolysis?

ATP is consumed to convert glucose into fructose 1,6-bisphosphate.

What happens during the energy-generation phase of glycolysis?

ATP and NADH are produced from the conversion of glucose intermediates.

What is the importance of the proton gradient in cellular respiration?

It drives ATP synthesis during oxidative phosphorylation.

How does the Krebs cycle contribute to cellular respiration?

It generates electron carriers (NADH and FADH₂) and ATP while producing CO₂ as a waste.

What type of reaction do uncoupling proteins facilitate?

They facilitate thermogenic reactions by dissipating the proton gradient.

What is the role of citric acid in the Krebs cycle?

Citric acid is formed by the reaction of acetyl-CoA with oxaloacetate at the start of the Krebs cycle.

What is the primary purpose of cellular respiration?

To convert biochemical energy from nutrients into ATP for cellular processes.

What is the net gain of ATP from glycolysis per glucose molecule?

2 ATP.

How does glycolysis begin?

By phosphorylating glucose, which then splits into two three-carbon molecules.

What is the function of NADH in cellular respiration?

To transport electrons to the electron transport chain.

During which phase of cellular respiration is carbon dioxide released?

In the Krebs cycle.

What molecule is oxaloacetate transformed into during the Krebs cycle?

Citrate.

What is the role of oxygen in aerobic respiration?

To act as the final electron acceptor in the electron transport chain.

What occurs to the electrons during oxidative phosphorylation?

They are transferred to oxygen, forming water while generating ATP.

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

They donate electrons, which are passed down a series of protein complexes.

What is produced as a result of the H⁺ ion gradient in the electron transport chain?

ATP, via chemiosmosis.

What are the three main types of energy carriers in cellular respiration?

NADH, FADH₂, and ATP.

What is the fate of pyruvate in anaerobic conditions?

It is converted into lactate or ethanol, depending on the organism.

How many NADH molecules are produced in one turn of the Krebs cycle?

3 NADH.

What is the significance of substrate-level phosphorylation in metabolism?

It directly generates ATP from ADP and inorganic phosphate without involving the electron transport chain.

What is the role of coenzyme A in the Krebs cycle?

To transport acetyl groups into the cycle.

How does the metabolism of fats differ from glucose?

Fats are broken down into fatty acids and glycerol, which can be converted to acetyl-CoA.

What is the yield of ATP during alcoholic fermentation?

2 ATP per glucose molecule.

What are uncoupling proteins?

Proteins that dissipate the proton gradient, producing heat instead of ATP.

What are the end products of the Krebs cycle for one molecule of acetyl-CoA?

3 NADH, 1 FADH₂, 1 ATP, and 2 CO₂.

What is the purpose of the electron transport chain?

To generate a proton gradient for ATP synthesis.

What role do protein complexes play in the electron transport chain?

They facilitate the transfer of electrons and help pump protons across the membrane.

What is the effect of high ADP concentration on ATP production?

It stimulates the pathways of cellular respiration to produce more ATP.

What is the function of ATP in cellular activities?

ATP serves as the energy currency of the cell, powering biochemical reactions.