Cell Membrane and Transport

• The cell membrane is composed of phospholipids and proteins.

  • Phospholipids are arranged in a phospholipid bilayer.

  • The membrane is made up of hydrophilic phosphate heads and hydrophobic lipid tails.

  • The membrane is fluid, allowing for movement of substances.

The Fluid Mosaic Model

• Proposed in 1972.

• The cell membrane is fluid and can flow around objects.

• The cell membrane is a mosaic of components, including phospholipids, proteins, carbohydrates, and cholesterol.

Cell Membrane Function

• Retains cell contents.

• Acts as a selective barrier, regulating the movement of materials into and out of the cell.

Selective Transport

• Movement across the cell membrane is called selective transport.

• Membranes can be classified as impermeable, permeable, or semi-permeable.

Phospholipid Molecule

• Consists of a hydrophilic phosphate head and a hydrophobic lipid tail.

• This chemical makeup accounts for the fluidity of the membrane and its arrangement.

Phospholipid Bilayer

• Phospholipids arrange themselves into a phospholipid bilayer.

• The lipid tails point inward, away from water.

• The phosphate heads point outward, towards water.

• Various types of proteins are embedded in the bilayer.

Membrane Proteins

• Variety of proteins are embedded within the lipid layers.

• Membrane proteins serve various functions.

Cell Membrane Labels

• A fluid mosaic model of membrane structure.

• A three-dimensional model of membrane structure.

• Labels for phospholipids, hydrophilic heads, hydrophobic tails, hydrophobic regions of proteins, hydrophilic regions of proteins, glycolipids, glycoproteins, lipid bilayer, external layer, internal layer, and