Bioenergetics and Cellular Respiration Overview

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Questions and Answers

What are the two compartments formed by the double-membrane mitochondrion?

Nucleus and cytoplasm

Intermembrane space and cristae

Inner membrane and outer membrane (correct)

Cytoplasmic fluid and matrix

Which of the following stages of aerobic respiration occurs first?

Formation of acetyl-CoA

Glycolysis (correct)

Krebs cycle

Electron transport chain

What is the main product of glycolysis?

NADH

Pyruvate (correct)

Glucose

Acetyl-CoA

Which phrase describes the Energy Investment Phase of glycolysis?

Requires an investment of ATP Signup and view all the answers

What happens to pyruvate during the formation of acetyl-CoA?

It is converted to acetyl-CoA and CO2 is released Signup and view all the answers

In aerobic respiration, what is produced as a direct result of glucose oxidation?

Energy in the form of ATP Signup and view all the answers

Which of the following correctly describes the role of NAD+ in glycolysis?

Serves as an electron acceptor Signup and view all the answers

Where does glycolysis occur within a cell?

In the cytoplasmic fluid Signup and view all the answers

What is produced when a coenzyme-A is attached to pyruvate?

Acetyl-CoA Signup and view all the answers

How many NADH molecules are produced during one cycle of the Krebs cycle per glucose molecule?

6 Signup and view all the answers

Which molecule is regenerated at the end of the Krebs cycle?

Oxaloacetate Signup and view all the answers

What type of reactions do the electron transport chain involve?

Reduction-oxidation (redox) Signup and view all the answers

Which component carries high-energy electrons to the electron transport chain?

FADH2 Signup and view all the answers

Who received the Nobel Prize for the identification of the Krebs cycle?

Hans Adolf Krebs Signup and view all the answers

In which part of the cell does the Krebs cycle occur?

Matrix of mitochondria Signup and view all the answers

What is formed when a four-carbon molecule oxaloacetate accepts a two-carbon acetyl group?

Citric acid Signup and view all the answers

What is the total maximum ATP yield from one glucose molecule during aerobic respiration?

36 to 38 ATP Signup and view all the answers

How much ATP does the oxidation of FADH2 yield per molecule?

2 ATP Signup and view all the answers

Which process occurs in the absence of oxygen to generate ATP?

Fermentation Signup and view all the answers

What is the primary function of NADH produced during glycolysis?

Transfer electrons during fermentation Signup and view all the answers

What is the yield of ATP from the two NADH molecules produced in glycolysis in eukaryotes?

2 ATP Signup and view all the answers

Which organic molecule can enter glycolysis after being converted to pyruvate?

Glutamate Signup and view all the answers

What is the caloric value of one gram of lipid in the diet?

9 kcal Signup and view all the answers

Which of the following statements about the Krebs cycle is accurate?

It generates both NADH and FADH2. Signup and view all the answers

Which enzyme complex is responsible for reducing NADH?

NADH-Q reductase complex Signup and view all the answers

Which of the following electron carriers can exist in both oxidized and reduced forms?

All of the above Signup and view all the answers

What is the primary function of flavin mononucleotide (FMN) in the electron transport chain?

Transfers electrons from NADH-Q reductase to the next complex Signup and view all the answers

Which complex is located after the cytochrome b/c1 reductase complex in the electron transport chain?

Cytochrome c oxidase complex Signup and view all the answers

What process is represented by the equation 2 H+ + 1/2 O2 → H2O?

Reduction of oxygen Signup and view all the answers

Which of the following complexes directly contributes to the generation of a proton gradient?

Cytochrome c oxidase complex Signup and view all the answers

Which of the following statements about the electron transport chain is false?

Ubiquinone is a fixed component of the electron transport chain. Signup and view all the answers

What is the end product when electrons are finally transferred to oxygen in the electron transport chain?

Water Signup and view all the answers

What is the primary purpose of cellular respiration in cells?

To generate ATP for cellular work Signup and view all the answers

Which type of organism can switch from aerobic respiration to fermentation when oxygen is unavailable?

Facultative anaerobe Signup and view all the answers

In cellular respiration, what is the role of the final electron acceptor when it is oxygen?

It gets reduced Signup and view all the answers

What is the chemical equation for the process of cellular respiration using glucose as fuel?

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy Signup and view all the answers

What is the primary role of NADH and FADH2 in the electron transport chain?

To donate electrons with high energy content. Signup and view all the answers

What is often referred to as the 'power station' of the cell?

Mitochondrion Signup and view all the answers

Which process couples electron transport to ATP synthesis?

Oxidative phosphorylation. Signup and view all the answers

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

Oxygen (O2) Signup and view all the answers

What is produced alongside ATP during cellular respiration?

NADH Signup and view all the answers

Which of the following processes occurs in the mitochondria?

Cellular respiration Signup and view all the answers

What is formed as electrons from NADH or FADH2 lose energy while moving through the electron transport chain?

A proton gradient. Signup and view all the answers

What type of respiration occurs when there is no oxygen available?

Anaerobic respiration Signup and view all the answers

How does the proton gradient contribute to ATP synthesis?

It powers ATP synthesis as protons diffuse back into the matrix. Signup and view all the answers

What type of process is the diffusion of protons through ATP synthase?

Exergonic process. Signup and view all the answers

In which part of the cell does oxidative phosphorylation primarily occur?

Mitochondria. Signup and view all the answers

What is the role of ATP synthase in the process of ATP production?

To synthesize ATP using the energy from the proton gradient. Signup and view all the answers

Study Notes

Bioenergetics Overview

Covers energy, cellular respiration, and photosynthesis
Relates energy transfer within ecosystems

Cellular Respiration

Aerobic respiration: Requires oxygen; produces ATP from glucose.
Anaerobic respiration: Does not require oxygen; uses an inorganic molecule as the final electron acceptor instead.
Fermentation: Uses an organic molecule as the final electron acceptor to regenerate NAD+ for glycolysis.

Mitochondrion Structure and Function

Double-membrane structure with compartments:
- Outer membrane
- Inner membrane
- Intermembrane space
- Matrix
- Cristae (folds in inner membrane)

Aerobic Respiration (Redox Process)

Consists of four main stages:
- Glycolysis
- Formation of Acetyl-CoA
- Krebs cycle
- Electron transport chain/Chemiosmosis
The overall reaction pathway for glucose is: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
Oxidation and reduction occur during the process

Glycolysis

Breakdown of glucose into pyruvate (in the cytosol)
Two phases:
- Energy investment phase (requires ATP)
- Energy liberation phase (produces ATP and NADH)
Net gain of 2 ATP, 2 NADH, and 2 Pyruvate

Formation of Acetyl-CoA

Occurs in the mitochondria
Pyruvate is converted to Acetyl-CoA
Generates NADH and releases CO₂

Krebs Cycle (Tricarboxylic Acid Cycle)

Takes place in the mitochondrial matrix
Acetyl-CoA enters the cycle and combines with oxalacetate to form citrate.
Series of eight reactions that complete the breakdown of glucose to CO2.
Produces 2 ATP, 6 NADH, and 2 FADH2 per glucose molecule

Electron Transport Chain

Complex series of electron carriers embedded in the inner mitochondrial membrane.
Electrons from NADH and FADH2 are passed along the chain releasing energy.
The energy is used to pump H+ ions into the intermembrane space.
This creates a gradient that drives ATP synthesis.

Chemiosmosis

Process of ATP synthesis fueled by the H+ gradient.
H+ ions diffuse back into the matrix through ATP synthase.
This drives the production of ATP from ADP.

Oxidative Phosphorylation

Coupled to the electron transport chain.
Most ATP synthesis occurs in this process.
ATP synthase is the enzyme responsible for ATP production

Summary of Aerobic Respiration ATP Production

Glycolysis: 2 ATP
Pyruvate grooming: 2 NADH
Krebs cycle: 2 ATP + 6 NADH + 2 FADH₂
Total ATP per glucose molecule (~36-38 ATP) *Depending on the shuttle system

Fermentation

Alternative energy production in the absence of oxygen.
Two common types:
- Alcoholic fermentation
- Lactic acid fermentation
Regenerates NAD+ to allow glycolysis to continue, enabling a low yield of ATP production through substrate-level phosphorylation.

Other Organic Molecules as Fuels

Carbohydrates (glucose), proteins (amino acids), and fats (glycerol and fatty acids) can all be used as fuels for cellular respiration.
Each molecule has different entry points.
Different fuels will yield different amounts of ATP.

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Description

This quiz covers essential concepts in bioenergetics, focusing on energy transfer in cellular respiration and photosynthesis. Key topics include the structure and function of mitochondria, types of respiration, and the stages of aerobic respiration. Test your understanding of these critical biological processes!