Aim: How is the cell membrane built to do its job?

What are the functions of the cell membrane? 3 Basic Functions: Acts as a container Selectively permeable Communication

Function #1  Acts as a container  Holds the contents of the cell within

Function #2  Receptors  Has protein shapes on the cell membrane to communicate

Function #3  Selectively permeable  Allows only certain molecules in and out

Cell Membrane Structure  Bi-layer of lipids  Embedded withproteins

What are the two components of the cell membrane?  Lipids  Proteins

Components of Cell Membrane Lipids (lots of lollipops with legs) BI-LAYER OF LIPIDS

Proteins STRUCTURAL PROTEIN CHANNEL Membrane Proteins: 1.Transport Proteins: (Channels) 2.Receptor Proteins

Receptors RECEPTORS Proteins for communication Chemicals sent from other cells must fit Lock and key concept

Why is this model called the fluid mosaic model? Fluid – molecules are always moving Mosaic – made of many different molecules + =

How do some things get through the cell membrane?

Can the elephant get into the house?

How is the cell membrane different from an umbrella? An umbrella is impermeable It does not allow materials through

How is a window screen similar to the cell membrane? Both are semi- permeable. Only certain molecules pass.

What is the difference between these molecules?

Some are large… Polysaccharides – many units

Some are small… Water (Mickey Mouse) Monosaccharide – one unit AKA: GLUCOSE

Predict which molecules will get through the membrane SELECTIVELY PERMEABLE

Why do some things get through the cell membrane? Small molecules are more likely to get through the cell membrane compared to big molecules