Download The Cell Membrane

The Cell Membrane
Cell Membrane Basics
• Function: Controls the passage of materials into
and out of a cell
• Double layer of phospholipids (bilayer)
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
Phospholipid Composition
• 3 Parts
Polar Head
• 1) Phosphate Group
• 2) Glycerol
phosphate
glycerol
Nonpolar Tails
• 3) Two chains of fatty
acids
• Arrangement:
– Outside: Polar heads
Fatty
(hydrophilic)
acids
– Inside: Nonpolar Tails
(hydrophobic)
– What causes this arrangement?
Phospholipid Bilayer
Cell Membrane Contents
1) Cholesterol: strength & flexibility
2) Carbohydrates: identification
3) Various Proteins
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
– Maintain homeostasis
• Binds to ligands (molecules)
– Ex: hormones and
neurotransmitters
• Two kinds
– Membrane
– Intracellular
Draw, identify, label, & describe
carbohydrate
chain
protein
protein
cholesterol
protein channel
cytoskeleton
Review
1) Draw and label the basic components of the cell
membrane.
2) Name the 3 parts to a phospholipid?
3) Which part(s) make up the head of a phospholipid?
4) Which part(s) make up the tails of a phospholipid?
5) Which part of phospholipid always seems to be in
contact with a watery environment? Why?
6) Which membrane protein supports the cell
membrane?
7) Which membrane protein allows materials to pass
through?
8) What qualities/characteristics of a cell membrane
help the cell to maintain homeostasis?