Lipids and Cell Membrane Structure

Lipids make up MOST of the cell membrane Lipids are not soluble in water Lipids store large amounts of energy The monomers (smallest part of a lipid) are called fatty acids Fatty acids can combine to make complex lipids by a reaction called dehydration synthesis (aka condensation)

1. Carboxyl Head -COOH Polar – attracted to water Hydrophilic – “water loving” 2. Hydrocarbon Tail H-C chain Nonpolar – stays away from water Hydrophobic – “water fearing” Fatty Acids – unbranched carbon chain that makes up most lipids 2 parts:

Types of Fatty Acids Saturated –Each C always bonded to 4 other atoms –Molecule contains the max. # of H atoms Unsaturated –Double/triple bonds between some C atoms –Less H atoms needed

Phospholipids are lipids with 2 fatty acids attached to one glycerol. They have a polar and a non-polar end that align in the cell membrane forming a bi-layer

Cell Membrane Structure The cell membrane contains fats, proteins, and carbohydrates.

2 Kinds of cell membrane proteins 1.Integral Proteins  Proteins that penetrate completely through the lipid bilayer (inside)  Function to help transport different substances into and out of the cell. 2. Peripheral Proteins  Embedded into the bilayer  Located on the outside surface fluid mosaic model

Cell Membrane Functions It controls what enters and exits the cell. It is considered selectively permeable since it only lets certain molecules into and out of the cell It maintains the cell shape It connects each cell to other cells near it It can allow movement of the cell because the parts can move around each other, called the fluid mosaic model fluid mosaic model