1. The Cell Membrane

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

5. 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

6. 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?

7. Phospholipid Bilayer

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

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

11. 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

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

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

14. 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?