Biology: Respiration Processes

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Questions and Answers

What is the primary purpose of respiration in cells?

Release of energy stored in carbohydrates (correct)

Production of oxygen

Storage of ATP

Synthesis of glucose

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

-15.2 kcal/mol

-686 kcal/mol (correct)

2 ATP

36 ATP

How much energy is practically yielded, in ATP, from one mole of glucose in the presence of oxygen?

40 ATP

36 ATP (correct)

2 ATP

12 ATP

What percentage efficiency is achieved via aerobic respiration?

40% Signup and view all the answers

Which stage of respiration occurs in the cytoplasm and can operate in the absence of oxygen?

Glycolysis Signup and view all the answers

What do pyruvates convert into without oxygen during glycolysis?

Lactate or ethanol Signup and view all the answers

Where does the TCA Cycle take place within a cell?

Mitochondrial matrix Signup and view all the answers

What is the main function of the Electron Transport Chain?

Reduce O2 to H2O and generate ATP Signup and view all the answers

How many ATP are yielded from anaerobic respiration per mole of glucose?

2 ATP Signup and view all the answers

According to the Chemiosmotic Theory, what is necessary for ATP synthesis during respiration?

H+ electrochemical gradient Signup and view all the answers

What is created due to the accumulation of protons (H+) in the intermembrane space?

A proton gradient or electrochemical gradient Signup and view all the answers

What role does the proton motive force (PMF) play in cellular respiration?

Drives the synthesis of ATP Signup and view all the answers

Which complexes in the mitochondrial inner membrane function as proton pumps?

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

Where is ATP synthase located within the mitochondrion?

Inner mitochondrial membrane Signup and view all the answers

What is the result of the electrochemical potential difference generated by proton transport?

Creation of a proton gradient Signup and view all the answers

What does ADP together with inorganic phosphate (Pi) produce when combined with energy from protons?

ATP Signup and view all the answers

What phenomenon describes the flow of protons across the inner mitochondrial membrane during ATP synthesis?

Chemiosmosis Signup and view all the answers

In terms of protons, what is the primary function of the inner mitochondrial membrane?

To separate the mitochondrial matrix from the intermembrane space Signup and view all the answers

What is the primary function of ATP synthase in cellular respiration?

To synthesize ATP using a proton gradient Signup and view all the answers

How many protons are required to synthesize one molecule of ATP?

4 protons Signup and view all the answers

Which of the following is NOT an alternate fate of glucose during respiration?

Conversion to carbon dioxide Signup and view all the answers

What factors can affect the respiration rate in plants?

Temperature and oxygen levels Signup and view all the answers

Which component of ATP synthase is responsible for acting as a channel for proton transport?

Fo complex Signup and view all the answers

Study Notes

Respiration

Biological process where stored energy in carbohydrates is released in a stepwise, controlled manner.
Released energy is used to synthesize ATP.
ATP is essential for plant cell maintenance, growth, and development.

Aerobic Respiration

C6H12O6 + 6O2 + 6H2O → 6CO2 + 12H2O + energy (ATP)
1 mole of glucose produces 36 ATP

Efficiency of Aerobic Respiration

ADP-P bond releases -7.6 kcal/mol ATP when broken.
Theoretical energy yield from burning 1 mol glucose = -686 kcal/mol
Practical yield from burning 1 mol of glucose in the cell with oxygen = 36 ATP.
Efficiency = 40% (274/686 x 100)

Efficiency of Anaerobic Respiration

ADP-P bond releases -7.6 kcal/mol ATPwhen bond is broken.
Theoretical energy yield from burning 1 mol glucose = -686 kcal/mol
Practical yield from burning 1 mol of glucose in the cell without oxygen = 2 ATP.
Efficiency = 2.2% (15.2/686 x 100).

3 Stages of Respiration

Glycolysis: Occurs in the cytoplasm, with or without oxygen; breaks down glucose (6C) to two pyruvates (3C).
TCA Cycle: Occurs in the mitochondrial matrix, only if oxygen is present; converts pyruvate via acetyl CoA to CO2, generating NADH and FADH2.
Electron Transport Chain: Occurs in the mitochondrial membranes (cristae); transfers electrons from NADH and FADH2 to reduce O2 to H2O and generate ATP.

Mitochondria

Spherical to oval: around 1 micron in diameter
Number of mitochondria per cell increases with demand for respiration; 300-1000/root tip cell.
Double-membrane bound:
- Outer membrane is smooth.
- Inner membrane folds to form cristae.
- Inner membrane controls movement in and out of the mitochondria.
- Inner membrane is the site of electron transport.
Matrix lies within the inner membrane.

Glycolysis

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

TCA Cycle

Requires oxygen.
Occurs in the mitochondrial matrix.
Involves a series of enzyme-catalyzed reactions.
Converts pyruvate to CO2.
Generates electron carriers NADH and FADH2.
Produces ATP but primarily serves to generate NADH and FADH2 for the electron transport chain.

Electron Transport Chain

Requires oxygen.
Occurs in the mitochondrial membrane (cristae).
Involves a series of protein complexes embedded in the inner membrane.
Electron carriers NADH and FADH2 transfer electrons to the ETC.
Electrons move through the ETC releasing energy.
This energy is used to pump protons (H+) into the intermembrane space creating a proton gradient.
This electrochemical gradient is the proton motive force.
Oxygen is the final electron acceptor in the chain.

Chemiosmotic Theory

Electron transport drives proton pumping across the inner mitochondrial membrane.
This creates a proton gradient, also called an electrochemical gradient or a proton motive force, driving the synthesis of ATP by ATP synthase complex.

ATP Synthase

Protein assembly in the inner mitochondrial membrane.
Uses 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 the production of 1 ATP.

Alternate Fates of Glucose C

Not all glucose carbon is respired to CO2. Some intermediates branch off to:
- Amino acids
- Pentose sugars 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. (Note: Optimum temperature range exists for respiration).
Plant type.
Plant organ. (Different organs have varying metabolic needs)
Plant age. (Respiration rates vary based on stages of growth and development)

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Description

Explore the crucial biological processes of respiration, focusing on both aerobic and anaerobic methods. Understand the chemical equations, energy yields, and the efficiency of ATP production in plant cells. This quiz will enhance your knowledge of how energy from carbohydrates is utilized in living organisms.