The Cell Membrane

Cell Membrane Basics Function: Controls the passage of materials into and out of a cell Double layer of phospholipids (bilayer)

Charged CO2 water Cell Membrane Basics Function: Controls the passage of materials into and out of a cell Double layer of phospholipids (bilayer) Semi-Permeable: only some materials may enter/exit oxygen

Phospholipid Composition phosphate 3 Parts Polar Head 1) Phosphate Group 2) Glycerol Nonpolar Tails 3) Two chains of fatty acids Arrangement: Outside: Polar heads (hydrophilic) Inside: Nonpolar Tails (hydrophobic) glycerol Fatty acids What causes this arrangement?

Phospholipid Bilayer

Cell Membrane Contents 1) Cholesterol: strength & flexibility 2) Carbohydrates: identification 3) Various Proteins

Cell Membrane Contents glucose Cell Membrane Contents glucose Protein channel glucose 1) Cholesterol: strength & flexibility 2) Carbohydrates: identification 3) Various Proteins

Membrane Proteins Randomly scattered through the bilayer Various Functions Cytoskeleton: internal support Protein channels: allow objects to pass Enzymes: speed up chemical reactions Markers (carb chains): cell recognition; fight disease

Receptor Proteins Help cells communicate Binds to ligands (molecules) Maintain homeostasis Binds to ligands (molecules) Ex: hormones and neurotransmitters Two kinds Membrane Intracellular

Draw, identify, label, & describe carbohydrate chain protein cholesterol protein protein channel cytoskeleton

Review Draw and label the basic components of the cell membrane. Name the 3 parts to a phospholipid? Which part(s) make up the head of a phospholipid? Which part(s) make up the tails of a phospholipid? Which part of phospholipid always seems to be in contact with a watery environment? Why? Which membrane protein supports the cell membrane? Which membrane protein allows materials to pass through? What qualities/characteristics of a cell membrane help the cell to maintain homeostasis?