Cellular Respiration - Glycolysis, Oxidation of Pyruvates, Krebs Cycle, Electron Transport Chain

What is the main purpose of cellular respiration?

To make ATP.

How much ATP is produced from glycolysis?

2 ATP.

How much ATP is produced from the Krebs cycle?

2 ATP.

What is the total ATP yield from one glucose molecule after the Electron Transport Chain?

Approximately 36 ATP.

What is the Electron Transport Chain (ETC)?

A series of proteins built into the inner mitochondrial membrane that transport electrons.

What is required for the Electron Transport Chain to function?

Oxygen (O2) for aerobic respiration.

What is the role of the proton (H+) gradient in ATP production?

It drives the synthesis of ATP through ATP synthase.

What process links the Electron Transport Chain to ATP synthesis?

Chemiosmosis.

Who proposed the chemiosmotic hypothesis?

Peter Mitchell.

What happens to electrons as they move through the Electron Transport Chain?

They move from one carrier to the next, releasing energy to pump H+ across the membrane.

What is the final electron acceptor in the Electron Transport Chain?

Oxygen (O2).

What occurs if oxygen is unavailable during cellular respiration?

The Electron Transport Chain backs up, ATP production ceases, and cells run out of energy.

What is the function of NADH and FADH2 in the Electron Transport Chain?

They donate electrons and protons to the ETC.

What is the intermembrane space in mitochondria?

The fluid-filled space between the outer and inner mitochondrial membranes.

What is oxidative phosphorylation?

The process of ATP production linked to the flow of electrons down the Electron Transport Chain.

What is the significance of the term 'proton-motive force'?

It refers to the potential energy stored in the H+ gradient used to synthesize ATP.

What is chemiosmosis?

The diffusion of ions across a membrane, specifically H+ ions through ATP synthase.

What is the role of ATP synthase in cellular respiration?

It synthesizes ATP from ADP and inorganic phosphate (Pi) using the energy from the H+ gradient.

What is the structure of mitochondria relevant to ATP production?

Mitochondria have a double membrane with highly folded cristae that house the Electron Transport Chain.

What is the overall equation for cellular respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + ~40 ATP.

What happens to protons (H+) during the Electron Transport Chain?

They are pumped into the intermembrane space, creating a gradient.

What is the significance of the Krebs cycle in cellular respiration?

It produces electron carriers (NADH and FADH2) that feed into the Electron Transport Chain.

What is the primary product of glycolysis?

2 pyruvate (3C) molecules from one glucose (6C) molecule.

What are the net gains from glycolysis?

2 ATP and 2 NADH.

What happens to pyruvate if oxygen is available?

Pyruvate enters the mitochondria for further oxidation.

What is produced during the oxidation of pyruvate?

2 acetyl CoA and 2 CO2, along with 2 NADH.

What is the Krebs Cycle also known as?

The Citric Acid Cycle.

Where does the Krebs Cycle occur?

In the mitochondrial matrix.

How many steps are in the Krebs Cycle?

8 steps, each catalyzed by a specific enzyme.

What is the significance of NADH and FADH2 produced in the Krebs Cycle?

They are electron carriers that move electrons to the Electron Transport Chain.

What is the total yield of ATP from the Krebs Cycle per glucose molecule?

2 ATP, along with 8 NADH and 2 FADH2.

What is the role of ATP synthase in cellular respiration?

It synthesizes ATP by using a H+ gradient to bond Pi to ADP.

What is the function of the highly folded inner membrane of mitochondria?

It provides more surface area for membrane-bound enzymes involved in ATP production.

What does the term 'endosymbiosis' refer to in the context of mitochondria?

It suggests that mitochondria evolved from bacteria that entered into a symbiotic relationship with eukaryotic cells.

What is the final product of glucose oxidation in cellular respiration?

CO2 and ATP.

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

It powers the ATP synthase to produce ATP from ADP and Pi.

What is the main purpose of cellular respiration?

To convert biochemical energy from nutrients into ATP.

How does the Krebs Cycle contribute to energy production?

By producing electron carriers that feed into the Electron Transport Chain, leading to ATP generation.

What are the three main stages of cellular respiration?

Glycolysis, the Krebs Cycle, and the Electron Transport Chain.

What is produced during the Krebs Cycle besides ATP?

NADH, FADH2, and CO2.

How does the Krebs Cycle relate to glycolysis?

Glycolysis produces pyruvate, which is then oxidized to enter the Krebs Cycle.

What is the role of coenzyme A in the oxidation of pyruvate?

It helps convert pyruvate into acetyl CoA.

What happens to the electrons carried by NADH and FADH2?

They are transferred to the Electron Transport Chain to generate ATP.

What is the primary purpose of glycolysis?

To produce ATP by breaking down glucose.

What does the term 'glycolysis' mean?

It means 'splitting sugar' (from 'glyco' meaning sugar and 'lysis' meaning splitting).

Where does glycolysis occur in the cell?

In the cytosol.

What is the net yield of ATP produced from one glucose molecule during glycolysis?

2 ATP.

What are the two products formed from glucose during glycolysis?

2 pyruvate molecules.

What are the two key energy carriers produced in glycolysis?

2 NADH and 2 ATP.

What is the significance of glycolysis in evolutionary terms?

It is an ancient pathway that represents the first energy transfer mechanism before the evolution of aerobic respiration.

What type of atmosphere did the first cells exist in?

An anaerobic atmosphere, without free oxygen (O2).

What is the initial energy investment required for glycolysis?

2 ATP are consumed to prepare glucose for splitting.

What happens during the energy payoff phase of glycolysis?

ATP and NADH are produced through the conversion of G3P to pyruvate.

What is substrate-level phosphorylation?

A process in glycolysis where ATP is produced directly from ADP and a phosphorylated substrate.

What happens to NADH in the absence of oxygen?

It is recycled back to NAD+ through fermentation processes.

What are the two types of fermentation that can occur after glycolysis?

Alcohol fermentation and lactic acid fermentation.

What is produced during alcohol fermentation?

Ethanol and carbon dioxide from pyruvate.

What is produced during lactic acid fermentation?

Lactic acid from pyruvate.

How does lactic acid fermentation differ from alcohol fermentation?

Lactic acid fermentation is reversible and can convert lactate back to pyruvate when oxygen is available.

What is the role of ATP synthase in cellular respiration?

It synthesizes ATP by using a proton gradient to bond Pi to ADP.

What is the overall reaction of glycolysis?

Glucose + 2 ADP + 2 Pi + 2 NAD+ → 2 pyruvate + 2 ATP + 2 NADH.

What is the energy accounting of glycolysis?

Net gain of 2 ATP and 2 NADH after an initial investment of 2 ATP.

What is the significance of pyruvate in cellular respiration?

It serves as a branching point for either fermentation or entry into the Krebs cycle for aerobic respiration.

What happens to NAD+ during glycolysis?

It is reduced to NADH during the oxidation of G3P.

What is the role of enzymes in glycolysis?

Enzymes facilitate each step of the glycolysis pathway, ensuring efficient conversion of glucose to pyruvate.

What is the evolutionary significance of glycolysis in modern cells?

All modern cells utilize glycolysis, indicating its fundamental role in energy metabolism.