CELL (PLASMA) MEMBRANEChapter 4

Pg. 77-78

Homeostasis

• Balanced internal conditions of cells• Maintained by cell membrane controlling what enters or leaves cell.

Cell (Plasma) Membrane• Function:

• Protective barrier• Semi-permeable: Regulated transport of molecules in and out of

cell

Cell (Plasma) Membrane• Function:

• Protective barrier• Semi-permeable: Regulated transport of molecules in and out of

cell • Allow cell recognition• Interact with the environment

Structure1. Phospholipid Bilayer - Two layers of phospholipids

Structure1. Phospholipid Bilayer - Two layers of phospholipids

a) Phospholipid contains:o 2 fatty acid chains that are nonpolar (hydrophobic)o Polar head (hydrophilic)

Structure1. Phospholipid Bilayer - Two layers of phospholipids

a) Phospholipid contains:o 2 fatty acid chains that are nonpolar (hydrophobic)o Polar head (hydrophilic)

b) Fatty acid tails create a hydrophobic center

Membrane Structure2. Membrane Proteins-embedded in the lipid layer

a. Integral Proteins: extend through both sides of membrane

Membrane Structure2. Membrane Proteins-embedded in the lipid layer

a. Integral Proteins: extend through both sides of membrane• Receptor Proteins: binds to substances outside the

cell

Membrane Structure2. Membrane Proteins-embedded in the lipid layer

a. Integral Proteins: extend through both sides of membrane• Receptor Proteins: binds to substances outside the cell• Transport (channel) Proteins: Aids in moving

substances across membrane• Glycoproteins (with Carbs): cell identification

Membrane Structure2. Membrane Proteins-embedded in the lipid layer

b. Peripheral Proteins: only on one side of membrane

-Enzymes (assist in chemical reactions)

Membrane Structure3. Cholesterol in bilayer for strength

• Blue Biology Textbook• Draw Figure 4-10 Pg. 77• Draw Figure 4-11 Pg. 78• Cell membrane coloring