Movement Through the Plasma MembraneChapter 3 Part B
General Outline•Cells & Tissues:–Cell Theory.–Basic structure of all cells•Phospholipid Bilayer:–Fluid Mosaic Model.–Components of Cell Membrane.•Cell Movement and Transport:–Cell Movement: Cilia vs. Flagella.–Transmembrane Transport.–Movement Through the Plasma Membrane•Cell Organelles•Cell Cycle•Body tissues:–Epithelial Tissue–Connective Tissue–Muscle Tissue–Nervous Tissue•Wound Healing
Movement Through the Plasma Membrane•There are two ways in which substances can enter or leave a cell: •1) Passive •2) Active
Membrane Transport•1) Passive:–Osmosis.–Simple diffusion.–Facilitated Diffusion:•Carrier Proteins:–Uniports vs. Symports vs. Antiports•Channels:–Voltage Gated.–Ligand Gated.•2) Active:–Active Transport:•Primary Active Transport: •Secondary Active Transport:–Exocytosis.–Endocytosis:•Phagocytosis.•Pinocytosis.
Passive Transport-> Simple Diffusion:•Diffusion is the net passive movement of particles (atoms, ions or molecules) from a region in which they are in higher concentrationto regions of lower concentration. •It continues until the concentration of substances is uniform throughout.
Diffusion Down Concentration Gradient
Passive Transport-> Simple Diffusion•Def: Diffusion is the movement of a substance from an area of higher solute concentration to one of lower solute concentration (down a concentration gradient).–a. The concentration gradient is the difference between concentrations in a space.•i.e. The difference in the concentrations of the molecules in the two areas is called the concentration gradient.–b. The end result of diffusion is uniform distribution of molecules.•The end result of diffusion is an equal concentration, or equilibrium, of molecules on both sides of the membrane. •At equilibrium, there is no longer an area of high concentration or low concentration, and molecules flow equally in both directions across the semipermeable membrane. •At equilibrium, equal amounts of a molecule are entering and leaving a cell.–c. Diffusion requires no expenditure of energy.•Molecules flowing down a concentration gradient is a natural process and does not require energy.