Transport across cell membranes

TRANSPORT ACROSS CELL MEMBRANES

Structure of cell membranes

-Phospholipid bilayer

-hydrophilic heads facing towards the water and hydrophobic tails inward away from water

-Fluid Mosaic model- fluid because phospholipids can slide over each other, mosaic due to the fact that the molecules look like a mosaic painting from above

-Contains, glycoproteins, receptor proteins, channel proteins (for facilitated diffusion), as well cholesterol to stabilize the cell membrane- ensures not too fluid when hot, etc. ( can have microvilli to increase surface area as well as lots of mitochondria for active transport)

Simple diffusion

Simple diffusion can occur across…