Cellular Energetics Notes

Lesson 1: Cellular Energetics

Aim: Understand the role of energy in living systems.

Processes:

• Cellular respiration: The biochemical process that cells use to convert nutrients into energy. This includes both aerobic (with oxygen) and anaerobic (without oxygen) pathways.

• Fermentation (Alcoholic and Lactic Acid): Metabolic processes that occur in the absence of oxygen, allowing for the production of energy.

  • Alcoholic Fermentation: Happening in yeast, converts glucose to ethanol and carbon dioxide.

  • Lactic Acid Fermentation: Occurs in muscle cells, converting glucose to lactic acid, particularly during intense exercise.

• Photosynthesis: The process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose.

Lesson 2: Enzymes

Aim: Understand the purpose and function of enzymes.

Definition: Enzymes are biological catalysts that speed up chemical reactions in the body, lowering the activation energy needed for reactions to occur.

Active Site: Area where the substrate binds on the enzyme; the specific region of an enzyme where catalysis occurs.

Enzyme-Substrate Complex: The temporary complex formed when an enzyme binds to its substrate, leading to a catalyzed reaction.

Lesson 3: Factors that Affect Enzyme Efficiency

Enzyme Activity: Dependent on optimal conditions:

• Temperature: Most enzymes have an optimal temperature range; beyond this, activity can decrease.

• pH: Each enzyme works best at a certain pH; deviations can result in reduced function or denaturation.

• Enzyme Concentration: Higher enzyme concentrations increase reaction rates until substrate becomes limiting.

• Substrate Concentration: Increasing substrate concentration raises the reaction rate to a point of saturation.

Denaturation: Extreme conditions can alter enzyme shape, impacting its ability to function effectively by disrupting the hydrogen bonds and hydrophobic interactions that maintain its structure.

Inhibition:

• Competitive Inhibition: Inhibitor competes with the substrate for the active site; increasing substrate concentration can overcome this.

• Non-Competitive Inhibition: Inhibitor binds to a different site, altering the enzyme's shape and reducing activity, regardless of substrate concentration.

Lesson 4: Photosynthesis

Aim: Understand photosynthesis and how plants convert solar energy.

Stages:

• Light-Dependent Reactions: Occur in the thylakoid membranes and convert solar energy into chemical energy.

  • Inputs: Water (H2O) and light.

  • Outputs: NADPH, ATP, and oxygen (O2) as a byproduct.

• Light-Independent Reactions (Calvin Cycle): Occur in the stroma; utilize chemical energy to fix carbon dioxide into glucose.

Chlorophyll: Pigment that absorbs light energy (primarily blue and red wavelengths) and reflects green, essential for photosynthetic processes.

Lesson 5: Light-Dependent Reactions

• Occur on the thylakoid membrane.

• Inputs: H2O, light; Outputs: NADPH, ATP, and O2.

• Chemiosmosis: H+ ions create a gradient for ATP synthesis via ATP synthase, converting ADP to ATP.

Lesson 6: Light Independent Reactions (Calvin Cycle)

• Occur in the stroma.

• Inputs: CO2, ATP, NADPH; Outputs: Glucose, ADP, NADP+.

• Steps:

  1. Carbon Fixation (via rubisco): CO2 is incorporated into a 5-carbon sugar.

  2. Reduction: Generates G3P (glyceraldehyde-3-phosphate), which can be converted into glucose.

  3. Regeneration of RuBP: The molecule must be regenerated for the cycle to continue.

Lesson 7: Environmental Factors & Photorespiration

• Light Intensity: Increased light can boost photosynthesis rates until saturation is reached, after which it plateaus.

• Temperature: Influences enzymatic activity; high temperatures can lead to denaturation of photosynthetic enzymes.

• Oxygen Levels: High oxygen can increase rates of photorespiration, which reduces the efficiency of photosynthesis and carbon fixation.

Lesson 8: Cellular Respiration

Aim: Understand cellular respiration processes.

Types:

• Aerobic: Uses oxygen, generates more ATP (up to 36 ATP per glucose).

• Anaerobic: Occurs without oxygen (fermentation), yielding less energy (2 ATP per glucose).

Reaction Equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (ATP).

Lesson 9: Oxidative Phosphorylation

• Electron Transport Chain: Uses electrons from NADH and FADH2 to create a proton gradient across the inner mitochondrial membrane for ATP synthesis.

• Oxygen is the final electron acceptor, playing a critical role in producing water.

Lesson 10: Anaerobic Respiration

• Fermentation: Allows glycolysis to continue in the absence of O2, enabling ATP production.

• Types:

  • Alcoholic fermentation (in yeast): Converts glucose into ethanol and CO2.

  • Lactic acid fermentation (in muscle cells): Converts glucose into lactic acid, especially when oxygen is scarce.

Lesson 11: Fitness & Cellular Energy

• Molecular Variation: Essential for adaptability and survival, influencing metabolic efficiency.

• Example: Different hemoglobin types optimize oxygen absorption in varying environmental conditions, enhancing survival.

• Photosynthesis Flexibility: Various chlorophyll types evolve to maximize light absorption efficiency, critical for energy capture in different light