Cell Membrane

Plasma Membrane

Cell Membrane

• 2 layers (bilayer) of phospholipids

• Similar to a mayonnaise sandwich– 2 pieces of bread with may stuck together

• Each individual phosphoplipid has a – head that is hydrophilic– tail that is hydrophobic

The phospholipid

STOP!! BIG WORDS!!!!• Hydrophobic: Hydro = Water ; Phobic = afraid

– The tail of the phospholipid is hydrophobic

• Hydrophilic: Hydro = Water ; Philic = loving– The head of the phospholipid is hydrophilic

• Millions of these molecules line up together to form a cell membrane!

What is the cell membrane for?• Controls material

going into the cell

• Controls material going out of the cell

• Holds the cell together

• Able to “talk” with other cells and molecules

Phospholipid

Head

Tail

Cell Membrane

Cell Membrane

Cell Membrane• Membrane looks big? Picture this…….

• It would take 10,000 membranes to equal the thickness of one sheet of paper!!!

Cell Membrane Proteins

• Proteins are stuck throughout the cell membrane

• They act as tunnels letting large molecules into and out of the cell

Receptor Molecules

• Molecules that that help the cell “talk” with other cells or molecules

• Must fit together like a puzzle piece

Keep in mind…...

• Not all substances can pass through the cell membrane!!! Only certain substances when needed…….this is called

SELECTIVE PERMEABILITY….

• Know what this means……