The Cell Membrane Cell Membrane Basics Function Controls

The Cell Membrane

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

Phospholipid Composition • 3 Parts Polar Head • 1) Phosphate Group • 2) Glycerol Nonpolar Tails • 3) Two chains of fatty acids • Arrangement: – Outside: Polar heads – Inside: Nonpolar Tails

Phospholipid Bilayer

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

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

Receptor Proteins • Help cells communicate – hormones, neurotransmitters, & other ligands • Two kinds – Membrane – Intracellular

Recap 1) 2) 3) 4) 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? 5) Draw and label the basic components of the cell membrane. 6) Which membrane protein supports the cell membrane? 7) Which membrane protein allows materials to pass through?