Mitochondria and Cellular Respiration

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Questions and Answers

How many molecules of ATP are produced from one complete turn of the Krebs cycle?

1 molecule (correct)

4 molecules

3 molecules

2 molecules

Which of the following products is generated in the highest quantity during the complete breakdown of one glucose molecule through glycolysis and the Krebs cycle?

Reduced NAD (correct)

CO2

Reduced FAD

ATP

During the Krebs cycle, how many molecules of CO2 are released for each glucose molecule metabolized?

8 molecules

4 molecules (correct)

2 molecules

6 molecules

Which compound is not produced during the glycolytic pathway?

Carbon dioxide (CO2) Signup and view all the answers

How many turns of the Krebs cycle occur per glucose molecule during its metabolism?

2 turns Signup and view all the answers

What is the primary product of anaerobic respiration in muscles?

Lactic Acid Signup and view all the answers

How many ATP molecules are produced during anaerobic respiration?

2 ATP Signup and view all the answers

Which of the following is a product of ethanol fermentation in yeast?

Ethanol Signup and view all the answers

Where does aerobic respiration primarily occur in eukaryotic cells?

Mitochondria Signup and view all the answers

What is the byproduct of aerobic respiration?

Carbon Dioxide and Water Signup and view all the answers

What is produced during alcoholic fermentation?

Ethanol, Carbon dioxide, and energy Signup and view all the answers

What type of respiration occurs in the absence of oxygen?

Anaerobic respiration Signup and view all the answers

Which type of fermentation occurs in mammalian muscle tissue?

Lactic acid fermentation Signup and view all the answers

What is the byproduct of glucose breakdown during lactic acid fermentation?

Lactic acid Signup and view all the answers

Which organism primarily undergoes alcoholic fermentation?

Yeast Signup and view all the answers

How many molecules of NADH are produced in the initial stages of anaerobic respiration?

2 Signup and view all the answers

In anaerobic respiration, what is the main purpose of fermentation?

To regenerate NAD+ and continue ATP production Signup and view all the answers

Which molecule is not a product of alcoholic fermentation?

Lactic acid Signup and view all the answers

What is one function of the outer smooth membrane of the mitochondria?

To allow entry of small molecules needed for cellular respiration Signup and view all the answers

What structure within the mitochondria contains ribosomes and DNA?

Matrix Signup and view all the answers

Which metabolic process occurs in the cytoplasm?

Glycolysis Signup and view all the answers

What role do the stalked particles found in the cristae serve?

Facilitate ATP production using respiratory enzymes Signup and view all the answers

Which statement accurately describes the inner folded membrane of the mitochondria?

It is folded to form structures called cristae. Signup and view all the answers

What are cristae primarily involved in?

Increasing the surface area for respiration reactions Signup and view all the answers

What type of enzymes are primarily found in the mitochondrial matrix?

Respiratory enzymes Signup and view all the answers

What characterizes the mitochondrial DNA compared to nuclear DNA?

It is capable of coding for proteins independently. Signup and view all the answers

What is the primary energy yield from glycolysis during anaerobic respiration?

2 ATP Signup and view all the answers

In lactic acid fermentation, which compound acts as the final hydrogen acceptor?

Pyruvate Signup and view all the answers

What does lactate convert back into once oxygen supply is resumed?

Pyruvate Signup and view all the answers

What is the fate of lactate after it is produced during anaerobic respiration?

It is transported to the liver where it can be stored as glycogen. Signup and view all the answers

What is the reason for muscle fatigue and cramps during anaerobic respiration?

Accumulation of lactic acid Signup and view all the answers

What term describes the extra oxygen needed to break down lactate after exercise?

Oxygen debt Signup and view all the answers

What is the primary reason anaerobic respiration is used by muscles?

To provide ATP when oxygen supply is inadequate Signup and view all the answers

Why are enzymes crucial in metabolic pathways?

They speed up reactions by lowering activation energy. Signup and view all the answers

Study Notes

Mitochondria Structure

Double membrane: Outer smooth membrane is permeable to small molecules needed for cellular respiration (e.g., pyruvate). The inner folded membrane forms finger-like cristae projecting into the matrix.
Cristae: Contain stalked particles which contain respiratory enzymes.
Matrix: Contains ribosomes and DNA. Also contains soluble enzymes for cellular respiration.

Stages of Respiration

Glycolysis: Takes place in the cytoplasm.
Kreb's cycle (citric acid cycle/ tricarboxylic acid cycle): Takes place in the matrix of mitochondria.
- Each turn of the Krebs cycle produces:
  - 2 molecules of CO2
  - 1 molecule of ATP
  - 3 molecules of reduced NAD
  - 1 molecule of reduced FAD
ATP (adenosine triphosphate) synthesis by Chemiosmosis: Occurs in the inner mitochondrial membrane. Protons (H+) are pumped across the membrane from the matrix to the intermembrane space, creating a concentration gradient. This gradient drives the movement of protons back into the matrix through ATP synthase, generating ATP.

Anaerobic Respiration

Occurs in the absence of oxygen.
Two types:
- Alcoholic fermentation: Occurs in yeast and roots of plants in waterlogged soil. Produces ethanol, carbon dioxide, and energy (glucose -> ethanol + carbon dioxide + energy).
- Lactic acid fermentation: Occurs in mammalian muscle tissue. Produces lactic acid and energy (glucose -> lactic acid + energy).

Importance of Anaerobic Respiration in Muscles

When oxygen supply fails to meet muscle demand, muscles respire anaerobically.
Lactic acid produced lowers the pH and can inhibit muscle enzymes, causing muscle fatigue and cramps.
Once oxygen supply is resumed, lactate is converted back into pyruvate for the Krebs cycle or transported to the liver for breakdown or storage as glycogen.
Extra oxygen needed to breakdown lactate is known as "oxygen debt".

Metabolic Pathways and Enzymes

Many cellular respiration reactions occur through metabolic pathways where each step is catalyzed by a specific enzyme.
Enzymes lower the activation energy required for the reactions to take place.
Glucose is broken down into pyruvate through a series of steps, each with a specific enzyme.

Cellular Respiration Flowchart

Glucose is initially broken down via glycolysis to produce pyruvate.
In anaerobic conditions, pyruvate is further broken down to either ethanol and CO2 (alcoholic fermentation) or lactic acid (lactic acid fermentation).
In aerobic conditions, pyruvate enters the mitochondria to undergo the Krebs cycle and oxidative phosphorylation.
This process generates a significant amount of ATP, CO2, and water.

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Description

This quiz covers the structure of mitochondria and the stages of cellular respiration, including glycolysis and the Krebs cycle. Enhance your understanding of how ATP is synthesized and the role of mitochondrial membranes in these processes.