What is the potential of a cell made up of Zn/Zn21 and

Introduction to Biology Notes: Chapter 7­ Membrane Structure and Function  Plasma Membrane: boundary that separates the living cell from its surroundings - It is selective permeable  Selective Permeable: allows some substances to cross it more easily than others  Cellular Membranes: fluid mosaics of lipids and proteins  Amphipathic: contains hydrophobic and hydrophilic regions  Fluid Mosaic Model: states that a membrane is a fluid structure with a “mosaic” of various proteins embedded in it Factors that Affect Membrane Fluidity - Temperature - Cholesterol Membrane Protein: - Peripheral Proteins: bound to the surface of the membrane - Integral Proteins: penetrate the hydrophobic core  Transmembrane Proteins: integral proteins that span the membrane 6 Major Functions of Membrane Proteins: a. Transport b. Enzymatic activity c. Signal transduction d. Cell­cell recognition e. Intercellular joining f. Attachment to the cytoskeleton and extracellular matrix Role of Membrane Carbohydrates - Cell recognition  Aquaporins: facilitate the passage of water Transport Across Plasma Membrane - Passive transport o Diffusion o Osmosis o Facilitated diffusion - Active transport o Cotransport - Bulk transport o Exocytosis o Endocytosis  Passive Transport: substances diffuse down their concentration gradient with no energy investment  Dynamic Equilibrium: many molecules cross the membrane