Biology Chapter on Respiration

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Questions and Answers

What role does the proton gradient play in ATP synthesis?

It powers the conversion of ADP and Pi to ATP. (correct)

It drives the transport of electrons.

It inhibits the formation of ATP.

It regulates the temperature of the mitochondria.

How many protons are typically required to produce one molecule of ATP?

4 protons (correct)

2 protons

8 protons

3 protons

Which of the following is NOT a fate of glucose during respiration?

Production of fatty acids

Direct production of ATP (correct)

Conversion to amino acids

Conversion to nucleotides

Which components are part of ATP synthase that projects into the matrix?

Alpha and beta chains Signup and view all the answers

What factor does NOT affect the respiration rate in cells?

Color of the plant Signup and view all the answers

What is the primary product of aerobic respiration from 1 mole of glucose?

36 ATP Signup and view all the answers

Which of the following stages of respiration can occur without oxygen?

Glycolysis Signup and view all the answers

What is the efficiency percentage of aerobic respiration?

40% Signup and view all the answers

How many ATP are generated from anaerobic respiration of one mole of glucose?

2 ATP Signup and view all the answers

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

Mitochondrial matrix Signup and view all the answers

What is produced in the absence of oxygen during glycolysis?

Lactate or ethanol Signup and view all the answers

Which of the following best describes the function of mitochondria?

Energy production through respiration Signup and view all the answers

What is the role of the chemiosmotic theory in oxidative phosphorylation?

Creation of a H+ electrochemical gradient for ATP synthesis Signup and view all the answers

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

-686 kcal/mol Signup and view all the answers

What is the initial substrate of glycolysis?

Glucose Signup and view all the answers

What is the primary role of the proton motive force (PMF) in cellular respiration?

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

What causes the accumulation of protons (H+) in the intermembrane space during respiration?

The action of proton pumps in Complexes I, III, and IV. Signup and view all the answers

Which component is directly responsible for synthesizing ATP in mitochondria?

ATP synthase Signup and view all the answers

What effect does the electrochemical gradient have on ATP production?

It drives protons back into the mitochondrial matrix. Signup and view all the answers

Which statement best describes the role of ATP synthase?

It catalyzes the conversion of ADP and inorganic phosphate into ATP using stored energy. Signup and view all the answers

What type of gradient is created by the accumulation of protons in the intermembrane space?

Electrochemical gradient Signup and view all the answers

Which complexes in the electron transport chain act as proton pumps?

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

Where is ATP synthase located in the mitochondria?

Inner mitochondrial membrane Signup and view all the answers

Study Notes

Respiration

Process where energy stored in carbohydrates is released in a controlled manner
Energy is used to synthesize ATP
ATP is essential for plant cell maintenance, growth, and development

Aerobic Respiration

Chemical Reaction: C6H12O6 + 6O2 + 6H2O → 6CO2 + 12H2O + energy (ATP)
1 mole of glucose yields 36 ATP

Efficiency of Aerobic Respiration

Energy released from breaking an ADP-P bond is -7.6 kcal/mol ATP
Theoretical energy yield of burning 1 mole of glucose is -686 kcal/mol
Practical energy yield of burning 1 mole of glucose in the cell with oxygen is 36 ATP
Efficiency: (274 kcal/mol glucose / 686 kcal/mol glucose) * 100 = 40%

Efficiency of Anaerobic Respiration

Energy released from breaking an ADP-P bond is -7.6 kcal/mol ATP
Theoretical energy yield of burning 1 mole of glucose is -686 kcal/mol
Practical energy yield of burning 1 mole of glucose in the cell without oxygen is 2 ATP
Efficiency: (15.2 kcal/mol glucose / 686 kcal/mol glucose) * 100 = 2.2%

3 Stages of Respiration

Glycolysis
- Occurs in the cytoplasm
- Happens with or without oxygen
- Breaks down glucose (6C) into 2 pyruvates (3C)
TCA Cycle
- Occurs in the mitochondrial matrix
- Requires oxygen
- Converts pyruvate via acetyl CoA into CO2, generates NADH and FADH2
Electron Transport Chain
- Occurs in the mitochondrial cristae
- Transfers electrons from NADH and FADH2 to reduce O2 to H2O and generate ATP

Mitochondria

Spherical to oval shape
Approximately 1 micron in diameter
Number of mitochondria per cell increases with respiration demand (300-1000/root tip cell)
Double-membrane bound
- Outer membrane is smooth
- Inner membrane folds into cristae, controlling movement in and out of the organelle
- Inner membrane is the site of electron transport

Glycolysis

Found in all living organisms
The only stage that can occur without oxygen
Oldest stage of respiration, operating for billions of years in anaerobic organisms
Converts glucose to 2 pyruvates in the cytosol
With oxygen: pyruvate goes to the TCA cycle
Without oxygen: pyruvate is converted to lactate or ethanol (fermentation)
Yields 2 ATP/mole glucose in the absence of oxygen

Glycolysis Flowchart

Glucose (6C) 

2 Pyruvate (3C)
CO2     -O2            -O2
                +O2
Ethanol                        Lactate
                TCA Cycle

Chemiosmotic Theory (Peter Mitchell)

The transport of protons from the matrix to the intermembrane space generates a proton gradient across the membrane.
Protons accumulate in the intermembrane space, creating an electrochemical potential difference known as the proton motive force (PMF).
This PMF drives ATP synthesis by the ATP synthase complex.

Inner Mitochondrial Membrane (IMM)

IMM - Inner mitochondrial membrane
IMS- Inter membrane space
OMM- outer mitochondrial membrane

ATP Synthase

Protein assembly in the inner mitochondrial membrane
Uses the proton gradient to make ATP
Protons are pumped through a channel on the enzyme from the intermembrane space into the matrix
Approximately 4 H+ are required for every ATP produced

NADH and FADH2

NADH yields 2.5 (3) ATP molecules
FADH2 yields 1.5 (2) ATP molecules

ATP Synthase Units

F1
- Projects into the matrix
- Contains 3 α, 3 β, gamma, delta, and epsilon chains
- Catalyzes ATP synthesis
- Peripheral catalytic sites are present on the beta subunits.
Fo
- Embedded in the membrane
- Acts as a channel for transport of H+

ATP Production

ADP + Pi → ATP
34 H+ are required to produce one ATP molecule (34 protons are pumped from the intermembrane space to the matrix)

Alternate Fates of Glucose Carbon (C)

Not all carbon from glucose is respired to CO2
Intermediates of respiration branch off to synthesize:
- Amino acids
- Pentoses for cell wall structure
- Nucleotides
- Porphyrin biosynthesis
- Fatty acid synthesis
- Lignin precursors
- Precursors for carotenoid synthesis, hormones

Factors Affecting Respiration Rate

Substrate concentration
ATP concentration
Oxygen concentration
Temperature
Plant type
Plant organ
Plant age

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Description

Explore the intricate processes of aerobic and anaerobic respiration. Learn how cells convert carbohydrates into energy through ATP synthesis and understand the efficiency of these metabolic pathways. This quiz covers key reactions, energy yields, and the importance of respiration in plant cell development.