Biology: Selectively Permeable Membranes

Membranes and Transport Mechanisms

• Selectively Permeable Membrane: Allows specific molecules or ions to diffuse through, enabling controlled entry and exit of substances.
• Peripheral Protein: Temporarily adheres to the membrane, playing roles in signaling or attachment but not firmly fixed.
• Integral Protein: Permanently embedded in the membrane, essential for transport and communication across the membrane.

Diffusion and Osmosis

• Diffusion: Process where particles spread from areas of higher concentration to lower concentration, promoting equilibrium.
• Osmosis: Specific type of diffusion for solvents through a semipermeable membrane from a less concentrated to a more concentrated solution to balance concentrations.

Types of Solutions

• Hypotonic: Solutions with lower solute concentration than another solution, leading to potential cell swelling.
• Hypertonic: Solutions with higher solute concentration than another solution, causing cell shrinkage.
• Isotonic: Solutions with equal solute concentration, resulting in no net movement of water across the membrane, maintaining cell size.

Transport Processes

• Passive Transport: Movement of substances across a membrane without energy expenditure; driven by concentration gradients.
• Active Transport: Movement of molecules against their concentration gradient, requiring energy and typically aided by enzymes.

Endocytosis and Exocytosis

• Endocytosis: Cellular process of taking in matter through membrane invagination to form a vacuole, facilitating nutrient uptake.
• Exocytosis: Release of substances from a cell via vacuole fusion with the cell membrane, enabling secretion of waste or signaling molecules.

Specialized Transport

• Facilitated Diffusion: A type of passive transport aided by integral proteins that increases the membrane's permeability for specific molecules.

Cell Integrity and Function

• Turgor Pressure: Internal pressure against the plant cell wall, maintaining shape and structure; crucial for plant rigidity.
• Cytolysis: Process where cells are disrupted or dissolved, often due to osmotic imbalance and resulting in cell bursting.
• Equilibrium: State where opposing forces are balanced; important in biological systems for maintaining homeostasis.

Test your knowledge of selectively permeable membranes with this quiz. Learn the definitions of key terms and concepts related to membrane biology and peripheral proteins. Perfect for students studying cell biology or biochemistry.