2.2 cell membranes

i) Know the structure and properties of cell membranes. ii) Understand how models such as the fluid mosaic model of cell membranes are interpretations of data used to develop scientific explanations of the structure and properties of cell membranes.

what is the function of cholesterol

• helps stabilise the cell membrane at different temperatures

• influences its fluidity

is phosphate head hydrophlic or hydrophobic

hydrophilic

is fatty acid tail hydrophilic or hydrophobic

hydrophilic

what is hydrophilic

water attracting

what is hydrophobic

water repelling

why is the sandwhich model wrong?

• because proteins also have hydrophilic and hydrophobic regions

what is the function of proteins

• cell transport and communication

what are the two types of proteins

intrinsic / integral - embedded in membrane with precise arrangment

extrinsic / peripheral - found in inner / outer surface of membrane

what does cholesterol do in low temperatures

• increases fluidity by preventing phospholipid tails from being too close

what does cholesterol do in high temperature

• it decreases fluidity by packing tails closer

how is cholesterol essential to the cell?

without cholesteorl membranes would break down and cells would burst

function of glycolipids and glycoproteins

• cell ot cell communication

• they bind with substancesin the cells surface

• they work as antigenx

how do molecules pass through the partially permeable membrane

• small / non - polar - can pass thorough gaps between phospholipids

• large / polar molecules - pass through channel / carrier proteins

whats the fluid mosaic model