Foundation of Biology --> Chapter 7

Cellular Respiration

Process that harvests energy from carbohydrates and other fuel molecules to produce ATP.

Purpose of Cellular Respiration

Converts biochemical energy from nutrients into ATP for powering cellular activities.

Importance of Cellular Respiration

Provides energy for movement, growth, and essential cellular processes.

Energy Link

Connects energy from food to usable energy for cells.

ATP Full Name

Adenosine Triphosphate.

Main Energy Currency of Cells

ATP.

Where Most ATP Is Generated

Mitochondria.

Energy in ATP

Stored in high-energy phosphate bonds.

Steps from Simple Molecules to Living Cells

Simple molecules ‚Üí biomonomers ‚Üí macromolecules ‚Üí polymer complexes ‚Üí metabolic networks ‚Üí living cells.

Importance of Chemical Complexity

Each step builds molecular complexity essential for life.

Glucose Role

Primary energy source for cellular respiration.

Glucose Formula

C₆H₁₂O₆

Mitochondria Function

Organelle where most ATP is generated through respiration.

ATP Function

Stores and transfers energy within cells.

Where Cellular Respiration Occurs

In cytoplasm and mitochondria.

Products of Cellular Respiration

ATP, CO2, and H2O.

Types of Phosphorylation

Substrate-level and oxidative phosphorylation.

Key Point of Cellular Respiration

Food energy is harvested and stored as ATP.

ATP Powers

Movement, active transport, and biosynthesis.

ATP Use Example

Motor proteins and membrane transport.

Stages of Cellular Respiration

Glycolysis, Pyruvate Oxidation, Citric Acid Cycle, Oxidative Phosphorylation.

Stage 1 - Glycolysis

Glucose → Pyruvate, ATP, and NADH.

Stage 2 - Pyruvate Oxidation

Pyruvate → Acetyl-CoA, CO₂, NADH.

Stage 3 - Citric Acid Cycle

Acetyl-CoA → CO₂, ATP, NADH, FADH₂.

Stage 4 - Oxidative Phosphorylation

Electron carriers → ATP via ETC.

Oxidation

Loss of electrons or hydrogens.

Reduction

Gain of electrons or hydrogens.

Redox Mnemonic

OIL RIG: Oxidation Is Loss, Reduction Is Gain.

Glucose and Oxygen in Respiration

Glucose oxidized to CO₂; Oxygen reduced to H₂O.

NAD+/NADH Relationship

NAD+ is oxidized form; NADH is reduced form.

FAD/FADH2 Relationship

FAD is oxidized form; FADH₂ is reduced form.

Energy Release Through Oxidation

Oxidation releases energy to make ATP.

Stages of Energy Capture

Occurs during glycolysis, pyruvate oxidation, citric acid cycle, and oxidative phosphorylation.

Electron Carriers Function

Store and transfer energy from oxidation reactions to the ETC.

Main Electron Carriers

NADH and FADH₂.

Electron Transport Chain Role

Uses electrons from carriers to drive ATP synthesis.

Substrate-Level Phosphorylation

Direct ATP formation using a phosphate from a substrate.

Oxidative Phosphorylation

ATP formed using energy from electrons in the ETC; requires oxygen.

Oxygen Requirement in Oxidative Phosphorylation

Yes, oxygen acts as final electron acceptor.

ATP Production Comparison

Substrate-level produces less ATP than oxidative phosphorylation.

Free Energy Change in Respiration

Free energy decreases as energy is harvested and stored in ATP/NADH.

Respiration Type of Reaction

Exergonic ('downhill' energy release).

Glycolysis Location

Cytoplasm (cytosol).

Glycolysis Oxygen Requirement

Anaerobic; does not require oxygen.

Net Inputs of Glycolysis

Glucose, NAD+, ADP + Pi.

Net Outputs of Glycolysis

2 Pyruvate, 2 ATP, 2 NADH.

Phases of Glycolysis

Preparatory phase (uses 2 ATP), Cleavage phase, Payoff phase (produces 4 ATP, 2 NADH).

Purpose of Glycolysis

Breaks down glucose for initial ATP and NADH production.

Mitochondrial Matrix Function

Site of pyruvate oxidation and citric acid cycle.

Inner Membrane Function

Houses electron transport chain for oxidative phosphorylation.

Intermembrane Space Function

Area where H+ accumulates for ATP synthesis.

Pyruvate Oxidation Location

Mitochondrial matrix.

Inputs of Pyruvate Oxidation

Pyruvate, NAD+, Coenzyme A.

Outputs of Pyruvate Oxidation

Acetyl-CoA, CO₂, NADH.

Link Between Glycolysis and Citric Acid Cycle

Pyruvate oxidation connects the two processes.

Citric Acid Cycle Location

Mitochondrial matrix.

Inputs of Citric Acid Cycle

Acetyl-CoA, NAD+, FAD, ADP + Pi.

Outputs of Citric Acid Cycle

CO₂, NADH, FADH₂, ATP, CoA.

Energy Transfer in Citric Acid Cycle

Energy stored in NADH, FADH₂ , and ATP.

Role of Citric Acid Cycle

Completes oxidation of carbon fuels and transfers energy to carriers.

ETC Location

Inner mitochondrial membrane.

ETC Function

Transfers electrons from NADH and FADH2 to oxygen, pumping protons to create gradient.

ETC Protein Complexes

Complex I-IV and ATP synthase.

Final Electron Acceptor in ETC

Oxygen (O2).

Product Formed at End of ETC

Water (H2O).

Proton Gradient Purpose

Stores potential energy for ATP synthesis (proton motive force).

Chemiosmosis Definition

Movement of ions across a membrane to generate ATP.

ATP Synthase Subunits

F0 (membrane channel) and F1 (catalytic enzyme).

ATP Synthase Function

Converts proton flow into ATP via rotational energy.

Inputs to ETC

NADH, FADH₂, ADP + Pi, O₂.

Outputs from ETC

ATP, H₂O, NAD+, FAD.

Water Formation in Respiration

H+ and electrons combine with O₂ in the matrix to form water.

Overall Cellular Respiration Equation

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP.

Total ATP Yield (approx.)

About 30–32 ATP per glucose molecule.

Study Tip 1

Know the location, inputs, and outputs of each stage.

Study Tip 2

Focus on the purpose and energy flow of each process rather than every intermediate.

Study Tip 3

Understand which stages are aerobic vs anaerobic.

Study Tip 4

Remember that NADH and FADH₂ link earlier stages to ATP production.