Plasma Membrane & Cellular Transport

Cell Transport A cell has to move food and wastes into and out of the cell. Materials must move through the plasma membrane which maintains homeostasis in the cell. food waste food waste

Cell Transport The Plasma Membrane surrounds the cell. How does it work?

Plasma Membrane Boundary between the cell and its environment 1.Allows nutrients into the cell 2.Removes wastes and excess materials 3.Maintains homeostasis: a stable internal environment

Plasma Membrane How does it work? 1.Selectively permeable: only allows some molecules in the cell, keeps others out dyn/content/photo/2006/10/15/PH jpg

Plasma Membrane 2. Fluid Mosaic Model: membrane is flexible, made of many pieces working together watch?v=Qqsf_UJcfBc Molecules are able to move around within each layer of the membrane. Fluid Molecules moving around on surface create different patterns. Mosaic

Plasma Membrane 3. Phospholipid Bilayer: membrane is 2 layers, made of phospholipids with proteins mixed in

Plasma Membrane Parts Phosphate heads – hydrophilic (like water), outside and inside membrane Fatty Acid Tails – hydrophobic (fear water), inside membrane, like OREO cream Cholesterol – prevents fats from sticking together, stabilize membrane Transport proteins – move molecules into and out of cell Identification proteins – outside cell, “nametag” Support proteins – inside cell for framework, “skeleton” Carbohydrates – serve as markers or “nametags”

1. Diffusion - molecules move from an area of high concentration to low concentration NO ENERGY required, moves molecules from high concentration to low concentration Passive Transport

2. Osmosis – diffusion of water molecules across a selectively permeable membrane Passive Transport – no energy required

Solutions Isotonic solution – equal concentrations of solute (salt) inside and outside cell

Solutions Hypotonic solution – less solute in solution, more solute in cell, WATER FOLLOWS SALT, cells swell

Solutions Hypertonic solution – more solute in solution, less solute in cell, WATER FOLLOWS SALT, cells shrink

Osmosis in blood cells

Solutions – how transport affects animals and plants

Transport in Plants Healthy plant cells are crisp due to TURGOR PRESSURE Wilted plant cells are flaccid due to lack of water

Passive Transport – no energy required 3. Facilitated Diffusion – movement of molecules from high concentration to low concentration with help of membrane transport proteins High concentration Low concentration

Active Transport Requires energy Moves molecules against concentration gradient Moves molecules from area of low concentration to area of high concentration Examples: gated channels, sodium/potassium pumps, endocytosis, exocytosis

Active Transport Endocytosis and Exocytosis