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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?