Cell Membrane

Function

1. Separates cytoplasm from external environment

2. Regulates what enters and leaves cell

3. Cell identification

4. Cell-cell communication

Plasma membrane regulates movement of

materials due to its chemical

composition:Phospholipids

CholesterolProteins

Phospholipids

• Phospholipids BilayerPhospholipids have:1. Hydrophilic head

2.Nonpolar hydrophobic tail

Hydrophilic "heads" faces the watery environment inside and outside cell

Hydrophobic tail forced to face inward – away from water.

The phospholipids are

not bound together –

gives the membrane a

fluid nature

CHOLESTEROL

• Function:

1.Stabilizes membrane (structural support)

2.Cell communication (cell-cell and cell-hormone)

Some interesting facts

• Most common molecule in membrane (>50%)

• Due small size and weight – only 20% of membrane mass

• Is an amphipathic molecule Homework – find out what this means

Proteins

• Are embedded in membrane

• Serve different functions

Functions

• 1. Channel Proteins - small openings for molecules to diffuse through

• 2. Carrier Proteins- binding site on protein "grabs” molecules, pulls them into cell

• 3. Receptor Proteins – act as triggers that set off cell responses (such as release of hormones or opening of channel proteins)

• 4. Cell Recognition Proteins - ID tags, identify cell to immune system

• 5. Enzymatic Proteins - carry out metabolic reactions

LABEL YOUR DIAGRAM WITH THE FOLLOWING

DETAILS

Task: Due end of class

• Read pages 47 -49 in your text

• Answer questions 1 – 5 in practice section

• Explain the structure and function of glycoproteins.

• How are liposomes used in cancer treatment and gene therapy?

• What role might receptor proteins have in medical disorders such as Hypertension?