Cell Membrane & Transport Quiz

Cell Membrane

• Composed of a phospholipid bilayer with hydrophilic heads and hydrophobic tails.
• Embedded proteins facilitate transport and communication.
• Cholesterol contributes to membrane stability and fluidity.
• Semi-permeable: Selective in what it allows to pass through.
• Oxygen (O2) and carbon dioxide (CO2) can pass through.
• Large proteins and glucose cannot pass.
• Viruses attach to receptors, enter through endocytosis or membrane fusion to release their genetic material.

Cell Transport

• Passive Transport: No energy needed; movement from high to low concentration (diffusion, osmosis, facilitated diffusion).
• Active Transport: Energy (ATP) required; movement from low to high concentration (endocytosis, exocytosis).
• Endocytosis: Cell takes in large molecules by engulfing them (e.g., white blood cells engulfing bacteria).
• Exocytosis: Cell expels large molecules by fusing vesicles with the membrane (e.g., release of neurotransmitters).
• Diffusion: Movement of molecules from high to low concentration.
• Osmosis: Diffusion of water across a semi-permeable membrane.
• Hypotonic Solution: Lower solute concentration than the cell; water enters, causing swelling.
• Hypertonic Solution: Higher solute concentration than the cell; water exits, causing shrinking.
• Isotonic Solution: Equal solute concentration; no net water movement; cells retain their shape.
• Facilitated Diffusion: Passive transport aided by protein channels.
• Water Movement Across Membranes: Hypertonic: water exits, cell shrinks; Hypotonic: water enters, cell swells; Isotonic: water movement balanced.

Mitosis

• Prophase: Chromosomes condense, nuclear membrane breaks down.
• Metaphase: Chromosomes align in the center of the cell.
• Anaphase: Sister chromatids separate to opposite poles.
• Telophase: Chromosomes reach poles, nuclear membranes reform around each set.
• Cytokinesis: Cytoplasm divides, creating two identical daughter cells.

Cellular Respiration

• Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
• Purpose: Convert glucose into usable energy (ATP).
• Location: Glycolysis in the cytoplasm; Krebs cycle and electron transport chain in the mitochondria.