Cellular Respiration Overview

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Questions and Answers

What is the primary function of the electron transport chain in cellular respiration?

  • To generate ATP from the breakdown of glucose. (correct)
  • To break down glucose into pyruvate.
  • To generate NADH and FADH2.
  • To produce carbon dioxide as a waste product.

Which of the following is NOT a product of glycolysis?

  • Pyruvate
  • NADH
  • Carbon Dioxide (correct)
  • ATP

Which of the following statements accurately describes the relationship between glycolysis and the Krebs Cycle?

  • Both processes require oxygen to function effectively.
  • The products of glycolysis are used as reactants in the Krebs Cycle. (correct)
  • Glycolysis occurs in the mitochondria, and the Krebs Cycle occurs in the cytoplasm.
  • The Krebs Cycle occurs before glycolysis in the breakdown of glucose.

What is the primary difference between aerobic and anaerobic respiration?

<p>Aerobic respiration requires the presence of oxygen, while anaerobic respiration does not. (D)</p> Signup and view all the answers

How many molecules of ATP are produced directly during the Krebs Cycle?

<p>2 (B)</p> Signup and view all the answers

During glycolysis, glucose is broken down into two molecules of

<p>Pyruvate (A)</p> Signup and view all the answers

What is the role of NAD+ in glycolysis?

<p>To transport electrons from glycolysis to the electron transport chain. (D)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between photosynthesis and cellular respiration?

<p>Photosynthesis releases oxygen, and cellular respiration uses oxygen. (B), Photosynthesis uses carbon dioxide, and cellular respiration releases carbon dioxide. (C)</p> Signup and view all the answers

During fermentation, what is the primary reason organisms regenerate NAD+?

<p>To ensure continued glycolysis and ATP production when oxygen is limited. (D)</p> Signup and view all the answers

Which of the following processes is NOT a part of cellular respiration?

<p>Photosynthesis (D)</p> Signup and view all the answers

What is the primary function of ATP synthase in the electron transport chain?

<p>Using the proton gradient to synthesize ATP. (B)</p> Signup and view all the answers

Why is oxygen crucial for the electron transport chain?

<p>It acts as the final electron acceptor, allowing the chain to continue. (B)</p> Signup and view all the answers

What is the primary difference between lactic acid fermentation and alcoholic fermentation?

<p>The final product produced. (B)</p> Signup and view all the answers

Which of the following is a major benefit of pacing oneself during exercise?

<p>Reducing the build-up of lactic acid in muscles. (A)</p> Signup and view all the answers

What is the direct consequence of lactic acid build-up in muscles?

<p>Muscle fatigue and soreness. (C)</p> Signup and view all the answers

Why does heavy breathing occur after intense exercise?

<p>To clear lactic acid and convert it back to pyruvate. (B)</p> Signup and view all the answers

How does cyanide act as a deadly poison in the body?

<p>It binds to an enzyme in the electron transport chain, halting ATP production. (B)</p> Signup and view all the answers

Which of the following statements correctly explains the significance of cellular respiration for organisms?

<p>It is the primary process for generating ATP, providing energy for all cellular functions. (A)</p> Signup and view all the answers

Flashcards

Electron Transport Chain (ETC)

Final stage of cellular respiration where electrons are transferred to oxygen through protein complexes, producing ATP and water.

Role of Oxygen in ETC

Oxygen acts as the final electron acceptor in the ETC, allowing the chain to function and preventing backup.

ATP Synthase Function

Utilizes proton gradient created by ETC to synthesize ATP during chemiosmosis.

Fermentation

Anaerobic process that allows ATP production when oxygen is absent, occurring after glycolysis.

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Lactic Acid Fermentation

Type of fermentation in muscle cells converting pyruvate into lactic acid and regenerating NAD+.

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Alcoholic Fermentation

Type of fermentation that converts pyruvate into ethanol and CO₂, regenerating NAD+.

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Proton Gradient

Created during ETC; it powers ATP synthase to make ATP as protons flow back across the membrane.

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Cellular Respiration Purpose

To convert glucose's chemical energy into ATP for cellular functions like growth and repair.

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Why Breathe Heavily Post-Exercise

Lactic acid builds up after intense work; oxygen is needed to clear it and convert back to pyruvate.

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Short vs Long Exercise Energy Use

Short-term uses fermentation for quick energy, while long-term relies on aerobic respiration for sustained energy.

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Aerobic

Requires oxygen for the process of cellular respiration.

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Anaerobic

Does not require oxygen for cellular processes.

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Calorie

The energy needed to raise 1g of water by 1°C; indicates food energy.

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Cellular Respiration

Process that converts food into usable energy in the form of ATP.

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Glycolysis

First step of cellular respiration, breaking glucose into pyruvate in cytoplasm.

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Krebs Cycle

Further breaks down pyruvate, generating electron carriers in the mitochondria.

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Reactants of Glycolysis

Inputs for glycolysis: Glucose, 2 ATP, NAD+; yield pyruvate and ATP.

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Study Notes

Aerobic vs. Anaerobic Respiration

  • Aerobic respiration requires oxygen (O₂).
  • Anaerobic respiration does not require oxygen.

Calorie

  • A calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1°C.
  • In biology, it often represents the energy content of food.

Cellular Respiration (CR)

  • Cellular respiration (CR) converts food (like glucose) into usable energy (ATP).
  • It has three main stages: Glycolysis, Krebs Cycle (Citric Acid Cycle), and Electron Transport Chain (ETC).

Glycolysis

  • What it is: The first stage of CR, breaking down 1 glucose molecule (6 carbons) into 2 pyruvic acid molecules (3 carbons each).
  • Where it happens: In the cytoplasm.
  • Importance: Starts glucose breakdown, producing ATP, NADH, essential for later stages.
  • Reactants: Glucose, 2 ATP, NAD⁺.
  • Products: 2 pyruvic acid, 2 ATP (net gain), 2 NADH.
  • Energy Source: Glucose breakdown.
  • Energy Destination: Stored in NADH and ATP.
  • Anaerobic? Yes.
  • Advantage: Rapid ATP production, useful in anaerobic conditions.
  • Carbon Follow-Up: 6-carbon glucose splits into two 3-carbon pyruvate molecules.

Krebs Cycle (Citric Acid Cycle)

  • What it is: Breaks down pyruvate further, releasing CO₂ and transferring high-energy electrons.
  • Where it happens: Mitochondrial matrix.
  • Importance: Produces high-energy electron carriers (NADH, FADH₂), essential for the ETC, and some ATP directly.
  • Reactants: Pyruvate, NAD⁺, FAD, ADP.
  • Products: 2 CO₂, 3 NADH, 1 FADH₂, 1 ATP per turn (2 total).
  • Energy Source: Electrons released as pyruvate breaks down.
  • Energy Destination: Stored in NADH and FADH₂ for the next step.
  • Aerobic? Yes.

Electron Transport Chain (ETC)

  • What it is: The final CR stage. Protein complexes pass electrons, forming water.
  • Where it happens: Inner mitochondrial membrane.
  • Importance: Produces most ATP in CR. Oxygen is vital as the final electron acceptor.
  • Reactants: NADH, FADH₂, O₂, ADP.
  • Products: H₂O, 32-34 ATP.
  • Energy Source: High-energy electrons from NADH and FADH₂.
  • Energy Destination: Powers ATP synthase by creating a proton gradient.
  • Aerobic? Yes.
  • ATP Synthesis: ATP synthase uses the proton gradient to make ATP.

Fermentation

  • What it is: Anaerobic process continuing ATP generation without oxygen.
  • Why it happens: Regenerates NAD⁺, essential for glycolysis to continue, when oxygen is unavailable.
  • Human Example: Lactic acid fermentation during vigorous exercise.
  • Benefit: Provides temporary ATP production when oxygen is limited, although less efficient.
  • After Exercise: The body needs oxygen to clear lactic acid, returning it to pyruvate for further breakdown (oxygen debt).
  • Types:
    • Lactic Acid Fermentation: Pyruvate to lactic acid, regenerating NAD⁺.
    • Alcoholic Fermentation: Pyruvate to ethanol and CO₂, regenerating NAD⁺.

Short vs. Long Exercise Times

  • Short-term (seconds-minute): Primarily relies on fermentation.
  • Long-term (minutes-hours): Primarily uses aerobic respiration.

Overall Role of Cellular Respiration

  • CR converts glucose's chemical energy into usable ATP, powering essential cellular functions.

Why Organisms Do CR?

  • Organisms do CR to generate ATP for essential cellular activities.

###Cyanide

  • Cyanide is a highly effective poison because it blocks the electron transport chain, preventing ATP production. The body relies heavily on cellular respiration for energy, and by halting this process, cyanide causes rapid death.

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