Biology Chapter 9 - Cellular Respiration Flashcards

Cellular Respiration Overview

• Aerobic Respiration: An efficient energy production process requiring oxygen, utilized by most organisms, also known as cellular respiration.
• Anaerobic Respiration: Energy production methods that do not involve oxygen, mainly employed by bacteria in oxygen-poor environments.
• Fermentation: Inefficient energy generation used when anaerobic pathways are necessary or ATP is needed rapidly without oxygen.

Energy Flow in Ecosystems

• Energy enters ecosystems as sunlight and exits as heat.
• Key Energy-Storing Molecule: Glucose is essential for energy storage in biological systems.

Key Equations

• Photosynthesis Equation: 6 CO2 + 12 H2O → C6H12O6 + 6 H2O + 6 O2
• Respiration Equation: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP

Electron Transfer and Energy

• Oxidized: A substance that has lost electrons, whereas a Reduced substance has gained electrons.
• Dehydrogenation Reactions: Transfer hydrogen to NAD+ or FAD during redox reactions.
• Substrate-Level Phosphorylation: Direct phosphorylation of ADP or GDP through coupled reactions.

Stages of Cellular Respiration

• Four Stages: Glycolysis, Pyruvate Oxidation, Krebs Cycle, Oxidative Phosphorylation.
• Glycolysis Location: Occurs in the cytosol and does not require oxygen.
• Products of Glycolysis: Breaks glucose down into two pyruvate molecules, yielding two ATP.

Pathways and Processes

• Energy Investment Phase: Consumes two ATPs to yield two G3P molecules.
• Energy Payoff Phase: Produces four ATPs, along with two Pyruvates and NADH.
• Pyruvate Oxidation: Converts pyruvate into acetyl-CoA.

Krebs Cycle

• Alternative Names: Citric Acid Cycle, Tricarboxylic Acid Cycle, TCA Cycle.
• Krebs Cycle Location: Takes place in the mitochondria, producing two ATP molecules per cycle.
• FAD Reduction: FAD is reduced to FADH2 during the Krebs Cycle.

Oxidative Phosphorylation

• Involves the electron transport chain (ETC) and chemiosmosis, regenerating the energy charge of NADH and FADH2.
• ATP Production: 32-34 ATP molecules produced due to the proton gradient established during this process.
• Location of ETC: Takes place in the inner membrane of mitochondria, where H+ ions accumulate in the intermembrane space.

Chemiosmosis and ATP Synthesis

• ATP Synthase: Enzyme allowing transportation of protons down the concentration gradient to synthesize ATP.
• Efficiencies of Electron Carriers: Oxidation of NADH yields approximately 3 ATP, while oxidation of FADH2 yields about 2 ATP.

Final Electron Acceptor

• Oxygen (O2): Serves as the final electron acceptor in the electron transport chain, completing the respiration process.

Metabolic Control

• Feedback Inhibition: A regulatory mechanism where the end product of a metabolic pathway inhibits an enzyme within that pathway.
• Phosphofructokinase: Acts as a key regulatory enzyme in glycolysis, influencing the pathway based on cellular energy demands.