Transport: Passive and Active

Structure of Cell membranes Fluid not rigid Selectively permeable Made of a phospholipid bilayer Embedded with proteins (4 kinds) -cell surface markers -receptor proteins -enzymes - transport protein

Cell Membrane

Passive Transport Movement of substances from one side of the membrane to another WITHOUT the use of ENERGY Ex. Diffusion Facilitated diffusion osmosis

Diffusion Process where particles move from an area of high concentration to an area of lower concentration – Ex. Food coloring in water – Sugar in coffee – Spraying perfume

Facilitated Diffusion Membrane is a phospholipid bilayer. Substances that are non-polar tent to pass through easier than polar or large molecules…they need help. Proteins in cell membrane act as carriers and channels, helping (facilitating) molecules pass through. Ex. Glucose, Cl -

Osmosis Aquaporins – channel proteins that allow water to pass through membrane Osmosis – diffusion of WATER through a selectively permeable membrane Movement of water will occur until equilibrium is reached.

Effects of Osmosis in cells

Active transport Moving a substance against its concentration gradient, from a low to high concentration Requires energy via ATP

Sodium – Potassium Pump 3 Na+ ions out of the cell, 2 K+ ions in the cell

Vesicles Used by substances too large to use carrier proteins (ex. Proteins, polysaccharides) Endocytosis – movement of substances into cell by vesicle Pinocytosis phagocytosis

Vesicles Exocytosis – out of cell by vesicle (ex. proteins packaged by golgi body!!)