Biology Chapter 8 Lesson 3 - Cell Transport

Cell Transport Concepts

• Diffusion: Movement of particles from an area of high concentration to an area of low concentration, establishing equilibrium.
• Osmosis: Specifically refers to the diffusion of water through a selectively permeable membrane, critical for maintaining cell homeostasis.
• Selectively Permeable Membrane: A barrier that only allows certain substances to pass through while restricting others, important for controlling cellular environments.

Types of Transport

• Facilitated Diffusion: Uses carrier proteins to assist the movement of molecules across the membrane from high to low solute concentration without energy expenditure.
• Passive Transport: Diffusion across a biological membrane with no energy cost; includes diffusion, osmosis, and facilitated diffusion.
• Active Transport: Movement of substances against their concentration gradient using specific transport proteins and ATP, crucial for nutrient uptake and waste removal.

Vesicular Transport

• Exocytosis: Secretion process where vesicles fuse with the plasma membrane to release molecules outside the cell.
• Endocytosis: Intake of extracellular substances through vesicle formation from the plasma membrane, allowing cells to engulf materials.

Phospholipid Structure

• Phospholipid: Composed of a hydrophilic "head" (water-attracting) and two hydrophobic "tails" (water-repelling), forming the basis of cellular membranes.
• Hydrophilic: Attracted to water; found in the head of phospholipids.
• Hydrophobic: Repellent to water; characterizes the tails of phospholipids.

Solutions and Cell Behavior

• Hypotonic Solution: Lower solute concentration than inside the cell; leads to cell swelling as water enters.
• Hypertonic Solution: Higher solute concentration outside the cell; causes cell shrinkage as water leaves.
• Isotonic Solution: Equal solute concentration inside and outside the cell, maintaining cell shape without net movement of water.

Transport Mechanisms Insights

• Integral Proteins: Span the entire lipid bilayer, involved in transport and communication across the membrane.
• Peripheral Proteins: Located on the membrane's surface, lacking penetration through the bilayer; serve as enzymes and signaling molecules.
• Bulk Transport: Includes endocytosis and exocytosis to transport large molecules and particles across the cell membrane.

Additional Processes

• Pinocytosis: A form of endocytosis that specifically involves the uptake of liquid from the surrounding environment.
• Phagocytosis: A specialized type of endocytosis that engulfs large particles or even other cells, vital for immune response.

Lab Context

• Iodine as an Indicator: Useful for detecting the presence of starch, illustrating the principles of diffusion in a lab setup.
• Starch Movement: Starch remains in a baggie during experiments because its large size prevents it from diffusing out through the membrane.

Test your knowledge on cell transport concepts with this informative quiz. Explore key terms such as diffusion, osmosis, and selectively permeable membranes. Perfect for reviewing essential biological processes related to how substances move across cell membranes.