Flashcards in Chapter 4: The Structure and Function of the Plasma Membrane Deck (46)
What are the functions of the membrane and describe each! (7)
1. compartmentalization - encloses cell boundary and intercellular spaces..each compartment has different contents so specialized activities can occur without interference ..interference = diseases. *Independently regulated.
2. framework for biochemical rxns- ensures components are arranged for effective interaction
-ie. all ETC molecules are embedded in MIT M
3. selectively permeable M - prevents unrestricted exchange of molecules...method of communication (gap junctions in cardiac cells ex)....aquaporins = how water gets into cells.
4. transport- substances can be moved up or down [ ] gradient...up= expenditure of ATP....establishes ion gradients
5. signal transduction - bind ligands to M receptors...changes internal cellular activities (2nd messenger) ex: cyclic AMP= common messenger
6. intercellular interaction - recognition and signalling occurs between cells...ex: immune system!
7. energy transduction - one type of energy is converted into another~>..example photosynthesis.. Light+sugar
L> Sugar --->ATP= cellular respiration
Describe the structure of the plasma membrane!
-ratio of lipid to protein in membrane depends on which membrane , which cell and which organization it is in!
-glycoproteins: carb attached to protein
- glycolipid : carb attached to lipid
Mitochondrial membrane concentration?
- high  of protein to lipid!
Neuron membrane concentration?
- high  of lipid to protein
What is between the inner and outer leaflets? Also what the fuck are inner and outer leaflets? (maybe answer in the reverse order)
-inner leaflet is the phospholipids closest to the inside of the cell...outer is closer to the exterior
- between them is a hydrophobic region
What are the three membrane lipids?
All lipids that make up a membrane are _____
- amphipathic...have a water loving and hating region!
O - hydrophilic region
| \ - hydrophobic region.....
**they aggregate spontaneously in a membrane
- ____ and ___ backbone
- phospholipid and glycerol
- What are the four major phospholipids?
*phosphatidic acid (base of phospoglyceride)
- tail composed of?
- saturated FA and Unsaturated FA
*unsaturated = membrane fluid = not as compact...ie why there is a bend in the tail!
polar head group ----glycerol backbone |========= fatty chain
The polar head group can vary in phosphoglycerides. What are they? (6)
1. Dioleoyl Phosphatidic acid
2. Phosphatidic acid
3. Phosphatidyl-cholne (lecithin) (PC)
4. Phosphatidyl- serine (PS)
5. Phosphatidyl-ethanolamine (cephaline) (PE)
6. Phosphatidyl-inositol (PI)
- mainly found on the outer leaflet
- important in cell signalling
- some viruses can use it to gain entry into the cell
- found in cell M mainly of platelets
-important in blood clotting
- promotes membrane curvature
- inner leaflet of M = where it is found
PE and PC?
- neutral phsophoglycerides
- also have EPA ( five double bonds in FA tail) and DHA(6 double bonds in FA tail) aka omega 3's
L> FA that lowers cholesterol
- inner leaflet of PM
- flippase are enzymes that ensure they are on the right leaflet
- sign something is wrong if it is on the outer
L> aka cell is not functioning right
- prevents memory loss
- cell signalling and emulation of cellular metabolism and growth
- commonly found in the inner mitochondrial membrane
PS and PI have what kind of charge?
- ceramide molecules??
- sphingosine (sugar) + FA chain
** sugar containing lipid molecule at the PM surface
Sphingolipids are the most or least abundant lipid in PM?
- ceramide molecules types?
- Sphingomyelin ( ceramide + phosphorylcholine)
- Glycolipid (ceramide + CHO)
L> cerebroside (simple sugar)
L> ganglioside(cluster of sugars)
- protects PM from harsh exterior ...lipid acts a buffer to low pH of other enzymes
-electrical insulation : insulates axons
-cell recognition : cell service receptor
- binds cell to extracellular matrix ..helps it bind so the cell can grow.
- cell signalling
- can be released from PM to act as a signalling molecule for differentiation or proliferation of other cells... Also signal of cell death!
Sphingosine functions in?
signal transduction in PM
Accumulation of Sphingomyelin leads to?
- Niemann pick disease (lysosomal storage disease)
L> potential disease associated ?
- Gal + ceramide
- defect in degradation of cerebroside causes organs to malfunction... Gaucher's disease
L> Type 1 and 2
-type can be helped with an enzyme replacement therapy but for type 2 death occurs by age 2.
- GalNac + Gal + Glu + ceramide
- Tay Sachs Disease
L> fatal...build up of lipid in brain...die by age four...homozygous recessive.....
L> GM1 and GM3?
L> acts as cell surface receptor
L> influenze, cholera and bothcelism use to gain entry to the cell.
*cholera attaches to GM1
L> cyclic AMP (cAMP) increases in intracellular level of it which leads to an increase in sodium and water loss in the large intestine.
L> lack of it causes neurological diseases ..blindness...seizures etc
- flat , rigid