Bio Unit 2 Cellular Respiration

Chapter Overview

• Focuses on the processes of energy transformation and cellular respiration.

• Key concepts: metabolism, energy types, thermodynamics, cell respiration processes.

Specific Expectations

• Analyze metabolic processes and their relevance in various systems (biological, community).

• Understand terminology related to metabolism.

• Conduct investigations of cellular respiration.

• Explain chemical changes and energy conversions in aerobic vs anaerobic respiration.

• Explore matter and energy transformations during respiration, highlighting roles of organs and processes.

Role of Energy in Living Organisms

• All organisms require energy to survive, grow, reproduce.

• Source of energy: carbohydrates and other organic compounds.

• Energy is released through cellular respiration; in absence of oxygen, anaerobic processes occur.

Key Terms Defined

• Metabolism: Sum of all chemical processes in living cells.

• Metabolic Pathways: Step-by-step chemical reaction sequences.

• Catabolism: Breakdown of molecules, releasing energy.

• Anabolism: Building larger molecules from smaller ones, consuming energy.

Energy Forms and Changes

Types of Energy:

• Kinetic Energy: Energy of motion.

• Potential Energy: Stored energy.

• Bond Energy: Energy associated with chemical bonds.

Laws of Thermodynamics:

• First Law: Energy cannot be created or destroyed, only transformed.

• Second Law: Energy transformations increase the overall disorder (entropy) of the universe.

Free Energy Changes

• Free Energy (G): Energy available to do work within a system.

• If delta G < 0, the reaction is spontaneous (exergonic).

• If delta G > 0, the reaction requires energy input (endergonic).

ATP Hydrolysis

• Hydrolysis of ATP to ADP releases energy used to power cellular processes.

• Cycle: ATP hydrolysis to release energy, regeneration from ADP using energy from catabolic reactions.

Cellular Respiration Processes

Stages:

1. Glycolysis:

   • Occurs in cytoplasm.

   • Converts glucose into pyruvate.

   • Produces 2 ATP and 2 NADH.

2. Pyruvate Oxidation:

   • Converts pyruvate to Acetyl-CoA.

   • Produces NADH and CO2.

3. Krebs Cycle:

   • Occurs in mitochondrial matrix.

   • Generates 1 ATP, 3 NADH, 1 FADH2 per acetyl-CoA, with CO2 as a byproduct.

4. Oxidative Phosphorylation:

   • Electron transport chain uses NADH/FADH2 to create a proton gradient, producing many ATP via ATP synthase (chemiosmosis).

Oxygen's Role in Respiration:

• Serves as the final electron acceptor in the electron transport chain.

• Importance of oxygen in aerobic respiration highlighted vs anaerobic pathways using alternative electron acceptors.

Anaerobic Respiration and Fermentation

• Less efficient energy extraction compared to aerobic respiration.

• Fermentation Types:

  • Lactate Fermentation: Pyruvate to lactate to regenerate NAD+ in anaerobic conditions (muscle cells).

  • Ethanol Fermentation: Pyruvate to ethanol + carbon dioxide (yeast).

Metabolic Interconnections (Alternate Pathways)

• Other biomolecules (fats, proteins) can enter respiration pathways at various points based on cellular energy supply needs.

Regulation and Control of Metabolic Pathways

• Feedback mechanisms using ATP and other intermediates adjust enzyme activity in pathways, maintaining energy balance.

Cellular Respiration Summary

• Results in net production of approximately 30-38 ATP per glucose, depending on cellular conditions and type (eukaryotes vs prokaryotes).

• Major role of NADH and FADH2 as electron carriers in energy production.

Review/Reflect Questions

1. How does cellular respiration reflect both aerobic and anaerobic conditions?

2. Examine energy expenditure in various activities and its influence on metabolic pathways.

3. Discuss the implications of mitochondrial diseases on energy metabolism within cells.