Biology Chapter: Aerobic Respiration

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Questions and Answers

What primary function does ATP synthase serve in the mitochondria?

Catalyzing the breakdown of glucose

Transporting protons into the intermembrane space

Producing carbon dioxide during respiration

Catalyzing ATP synthesis from ADP and Pi (correct)

Which of the following factors does NOT affect the respiration rate?

Oxygen levels

Type of substrate

Presence of light (correct)

Temperature

From the provided data, how many protons are required to produce one ATP molecule using NADH?

10 protons (correct)

8 protons

6 protons

4 protons

What is one of the alternate fates of glucose during respiration?

Production of nucleotides Signup and view all the answers

Which part of ATP synthase is responsible for the movement of protons?

Fo unit Signup and view all the answers

What is the main role of the proton motive force (PMF) in the mitochondria?

It drives the synthesis of ATP by ATP synthase. Signup and view all the answers

Which statement accurately describes the location of protons during the establishment of the electrochemical gradient?

Protons accumulate in the intermembrane space. Signup and view all the answers

What components are identified as proton pumps in the mitochondrial electron transport chain?

Complexes I, III, and IV Signup and view all the answers

What is the function of ATP synthase in the inner mitochondrial membrane?

It synthesizes ATP from ADP and inorganic phosphate using the PMF. Signup and view all the answers

What happens to the protons after they accumulate in the intermembrane space?

They create a proton gradient that helps ATP synthesis. Signup and view all the answers

Which structure is crucial for the process of ATP synthesis in mitochondria?

ATP synthase complex Signup and view all the answers

What creates the electrochemical potential difference across the inner mitochondrial membrane?

The accumulation of protons in the intermembrane space. Signup and view all the answers

What does the term 'chemiosmotic' refer to in the context of ATP synthesis?

The coupling of electron transport to proton movement and ATP synthesis. Signup and view all the answers

What is the main product of aerobic respiration?

ATP Signup and view all the answers

How many ATP molecules are typically produced during anaerobic respiration from 1 mole of glucose?

2 Signup and view all the answers

Which stage of respiration occurs in the cytoplasm and does not require oxygen?

Glycolysis Signup and view all the answers

What is the theoretical energy yield from burning 1 mole of glucose in a calorimeter?

-686 kcal/mol Signup and view all the answers

During the TCA Cycle, what is pyruvate converted into?

Acetyl CoA Signup and view all the answers

Which of the following statements about mitochondria is NOT true?

All cellular respiration occurs in the mitochondria Signup and view all the answers

What is the efficiency percentage of aerobic respiration?

40% Signup and view all the answers

What is directly linked to ATP synthesis according to the chemiosmotic theory?

H+ electrochemical gradient Signup and view all the answers

What process occurs if no oxygen is present after glycolysis?

Fermentation occurs Signup and view all the answers

Study Notes

Respiration

Respiration is a biological process that releases energy stored in carbohydrates through a step-wise, controlled manner.
This energy is coupled with ATP synthesis.
ATP is vital for plant cell maintenance, growth, and development.

Aerobic Respiration

Aerobic respiration requires oxygen.
During aerobic respiration, glucose is broken down with oxygen to produce carbon dioxide, water, and energy (in the form of ATP).
The equation for aerobic respiration is C6H12O6 + 6O2 + 6H2O --> 6CO2 + 12H2O + energy (ATP)
One mole of glucose yields 36 ATP molecules through aerobic respiration.

Efficiency of Aerobic Respiration

Aerobic respiration is relatively efficient.
The theoretical energy yield from burning one mole of glucose in a calorimeter is -686 kcal/mol.
The practical yield of energy from burning one mole of glucose in a cell with oxygen is 36 ATP, which equates to -274 kcal/mol.
The calculated efficiency of aerobic respiration is 40%.

Efficiency of Anaerobic Respiration

Anaerobic respiration does not require oxygen.
Anaerobic respiration is much less efficient than aerobic respiration.
Although one mole of glucose theoretically yields -686 kcal/mol of energy, anaerobic respiration only produces 2 ATP, which translates to -15.2 kcal/mol.
This results in a calculated efficiency of only 2.2%.

3 Stages of Respiration

Respiration occurs in three stages: glycolysis, the TCA cycle, and the electron transport chain.
Glycolysis occurs in the cytoplasm and can occur with or without oxygen. This stage breaks down glucose (6C) into two pyruvate molecules (3C).
The TCA cycle takes place in the mitochondrial matrix and is only possible in the presence of oxygen. This cycle converts pyruvate via acetyl CoA into carbon dioxide, generating NADH and FADH2.
The electron transport chain occurs in the mitochondrial membranes (cristae). It transfers electrons from NADH and FADH2 to reduce oxygen to water and generate ATP.

Mitochondria

Mitochondria are spherical to oval organelles with a diameter of about one micron.
The number of mitochondria per cell increases with the demand for respiration.
A root tip cell can contain 300-1000 mitochondria.
Mitochondria are double-membrane bound organelles with a smooth outer membrane and an inner membrane that folds to form cristae.
The inner membrane controls movement of substances in and out of the mitochondria and it's the site of electron transport.
The matrix of the mitochondria is the space enclosed by the inner membrane.

Glycolysis

Glycolysis occurs in all living organisms.
It is the only stage of respiration that can occur without oxygen.
Glycolysis is the oldest stage of respiration and has operated for billions of years in anaerobic organisms.
This stage converts glucose to two pyruvate molecules in the cytosol.
In the presence of oxygen, pyruvate moves on to the TCA cycle.
In the absence of oxygen, pyruvate is converted to lactate or ethanol (fermentation).
Glycolysis yields 2 ATP per mole of glucose in the absence of oxygen.

TCA Cycle

The TCA cycle is also known as the citric acid cycle or Krebs cycle.
The TCA cycle occurs in the mitochondrial matrix.
The cycle begins with the conversion of pyruvate to acetyl CoA.
The cycle involves a series of enzymatic reactions that generate NADH and FADH2.
The end products of the cycle are carbon dioxide, ATP, NADH, and FADH2.

Electron Transport Chain

The electron transport chain occurs in the mitochondrial inner membrane (cristae).
NADH and FADH2, generated from the TCA cycle, deliver electrons to the electron transport chain.
This chain consists of protein complexes embedded in the membrane.
As electrons move through the complexes, protons (H+) are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient.
This proton gradient drives the synthesis of ATP by the ATP synthase complex.

Chemiosmotic Theory of Oxidative Phosphorylation

The coupling of ATP synthesis to respiration occurs indirectly, via a proton electrochemical gradient across the inner mitochondrial membrane.
According to the chemiosmotic theory, protons (H+) accumulating in the intermembrane space create an electrochemical potential difference, also known as the proton motive force (PMF).
This PMF drives ATP synthesis by the ATP synthase complex.

Proton-Dependent ATP Synthese

ATP synthase is a protein assembly in the inner mitochondrial membrane.
It uses the proton gradient to synthesize ATP.
Protons are pumped through a channel on the enzyme from the intermembrane space to the matrix.
Approximately 4 H+ are needed to produce one ATP.

ATP Synthase Structure

ATP synthase contains two units: F1 and Fo.
F1 is a peripheral catalytic site, projecting into the matrix. It contains three α, three β, and γ, δ, ε chains. This unit is involved in the catalysis of ATP synthesis.
Fo is embedded in the membrane and acts as a channel for the transport of H+ across the membrane.

Alternate Fates of Glucose Carbon

Not all glucose carbon is respired to carbon dioxide.
Intermediates of respiration can branch off to form:
- Amino acids
- Pentose sugars used for cell wall structure
- Nucleotides
- Porphyrins
- Fatty acids
- Lignin precursors
- Precursors for carotenoid synthesis and hormones

Factors Affecting Respiration Rate

Respiration rate is influenced by several factors, including:
- Substrate concentration
- ATP concentration
- Oxygen concentration
- Temperature
- Plant type
- Plant organ
- Plant age

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Description

Explore the process of aerobic respiration in this quiz. Understand how glucose is broken down with oxygen to yield energy in the form of ATP, and discover the efficiency of this crucial biological process. Test your knowledge on the equations and energy yields involved in aerobic respiration.