Lecture 2.1: Membranes and Transport Unit 2– The Working Cell Lecture 2.1: Membranes and Transport

Membranes and Chemical Activities Selective permeability Structure Phospholipid bilayer Hydrophilic head Hydrophobic tail Phospholipids in water

Which molecules get through?? Nonpolar Polar Fluid mosaic model…the fluid part of the model

The mosaic part of the model Glycoproteins and glycolipids

Proteins and functions

Passive Transport Diffusion No energy (passive transport) Down the concentration gradient Example in cells

Osmosis Passive transport of water Hypertonic solutions Hypotonic solutions Isotonic solutions

Osmoregulation Cells in hyper/hypotonic solutions

Facilitated diffusion Down the gradient, with help Transport proteins Ex: sugars, amino acids, water

Active transport Uses energy Transport proteins work against gradient with ATP as the energy source Na+ and K+

Proton pumps Coupled transport

Exocytosis and endocytosis Getting rid of big molecules Bringing big molecules in

Types of endocytosis Phagocytosis Pinocytosis Receptor-mediated endocytosis