Cell Membrane:
Structure and Function
Cell Membrane- boundary
- selectively permeable- lets certain things in
- lets certain things out
- maintains homeostasis
- recognizes foreign cells
- aids in cell recognition, communication
- Fluid Mosaic Model- not rigid
- many parts are constantly moving
- made of organic molecules
Phospholipid bilayer- two layer sandwich
- phosphate group- polar “head”
- hydrophilic- attracted to water
- 2 fatty acids- - non-polar “tail”
- hydrophobic- repels water
- repels polar molecules (K+, Na+)
Cholesterol
- Stabilizes phospholipid tails
- in hot and cold environments
- important for homeostasis
Proteins-move between phospholipids
- peripheral- on membrane surface
- integral- go through membrane
- 4 types
1. Marker protein/glycoprotein
- carbohydrates attached on cell exterior
(extracellular)
- helps in cell recognition
- integral
- ex: like a sign with the name of the cell
Hi! I’m a blood cell (skin cell, eye cell)
- important in immune system
- organ transplants
2. Receptor protein
- recognizes and binds to substances on
extracellular side
- integral
- ex: like a receptionist
knows what the cell wants & gets it
3. Transport/channel protein
- helps substances move into & out of cell
- integral
- ex: like a door in the cell
4. Enzyme
- help in chemical reactions
- peripheral extracellular or intracellular
Organelles made of membranes
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Cell membrane/plasma membrane
Mitochondria
Rough ER/smooth ER
Golgi
Lysosomes
Nuclear membrane
Vesicle
Vacuoles
Chloroplasts
Cilia/flagella
Organelles with NO membrane
- ribosomes
- Microtubule/microfilament
- Cell wall
- Cytoplasm
- Centriole
- Chromatin
- Nucleolus
http://www.youtube.com/watch?v=S7CJ7xZOjm0