(2.4) Biology - Transport Across Cell Membranes

Why is it called the ‘fluid mosaic model’

• fluid → phospholipid molecules can move around layers via diffusion

• mosaic → the membrane has protein molecules and their arrangement varies

label ts

• A → intrinsic protein

• B → fatty acid tail

• C → glycoprotein

• D → phospholipid head

• E → peripheral protein (support)

• F → phospholipid bilayer

• G → glycolipid

• H → carbohydrate

• I → cholesterol

function of membranes?

• provide support for cell

• controls what enters and exits

function of phospholipids ?

• allow lipid soluble substances to enter and exit cell

• prevent water soluble molecules from entering and exiting cell

• make membrane flexible

function of glycoprotein and glycolipids

• act as recognition sites

• help cells attach to eachother to form tissues

function of cholesterol

• decreases flexibility and permeability which decreases water loss

function of channel protein

• allows specific water soluble ions and water molecules to diffuse through

• used for facilitated diffusion

function of carrier protein

• changes shape when molecules or ions bind to active site and transports them across membrane

• used for active transport