Unit 2: Biochemistry Notes

Cell Membrane

• Fluid Mosaic Model: Describes the cell membrane structure.
• Phospholipid Bilayer:
  • The basic structure of the cell membrane.
  • Composed of hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails.
• Semi-permeable: The membrane allows only certain substances to pass through.
• Protein Channels and Pumps: Assist in the transport of specific molecules.
• Cholesterol and Carbohydrates: Also present in the cell membrane.

Transport Across Membranes

Passive Transport

• No energy required.
• Movement from high to low concentration.
• Driven by the concentration gradient (difference in concentration between two sides).
  • Diffusion: Movement of small particles (e.g., O_2).
  • Osmosis: Diffusion of water (H_2O).
  • Facilitated Diffusion: Uses protein channels for larger molecules (e.g., glucose).

Active Transport

• Energy required.
• Movement from low to high concentration.
• Involves the movement of large molecules.
• Example: Sodium/Potassium Pump

Types of Solutions

• Hypertonic: High solute concentration.
• Hypotonic: Low solute concentration.
• Isotonic: Equal solute concentration.

Endomembrane System

• Nucleus: Contains genetic material.
• Ribosome: Site of protein synthesis.
• Rough Endoplasmic Reticulum (ER): Has ribosomes attached for protein synthesis.
• Vesicle: Transport vehicle within the cell.
• Golgi Apparatus: Modifies and packages proteins.
• Lysosome: Contains enzymes for breaking down waste.
• Organelle: A structure within a cell.

Endocytosis and Exocytosis

• Endocytosis: Entering the cell.
  • Phagocytosis: Solid particles.
  • Pinocytosis: Liquid particles.
• Exocytosis: Exiting the cell.

Bioenergetics

Photosynthesis

• Occurs in plants, specifically in chloroplasts.
• Overall equation: 6CO2 + 6H2O \rightarrow C6H{12}O6 + 6O2
  • CO_2: Carbon Dioxide
  • H_2O: Water
  • C6H{12}O_6: Glucose
  • O_2: Oxygen
• Light-dependent Reaction:
  • Occurs in the thylakoid membrane (pancake-like structures in chloroplasts).
  • ATP and NADPH are created, and O_2 is released.
• Light-independent Reaction (Calvin Cycle):
  • Occurs in the stroma (syrup-like substance in chloroplasts).
  • Uses ATP and NADPH to create glucose.
• Chlorophyll: Pigment that attracts green light.

Cellular Respiration

• Occurs in mitochondria.
• Glycolysis:
  • Occurs in the cytoplasm.
  • Produces 2 ATP.
  • Anaerobic (does not require oxygen).
• Krebs Cycle:
  • Occurs in mitochondria.
  • Produces 2 ATP (for two cycles).
  • Aerobic (requires oxygen).
• Electron Transport Chain (ETC):
  • Occurs in mitochondria.
  • Produces 28-32 ATP.
  • Aerobic.
• Fermentation:
  • Anaerobic.
  • Alcoholic (in bacteria).
  • Lactic Acid (in human muscles).
  • Produces 2 ATP.

ATP (Adenosine Triphosphate)

• Energy is found in the bonds.
• Fully charged battery.
• ADP (Adenosine Diphosphate):
  • Partially charged battery.