Quiz 1 Flashcards
Ways membrane phospholipids can move?
- lateral diffusion within monolayer
- rotation
- flexion (inflection/flexing)
- flip flop (rare, maybe once a month)
Roles of plasma membrane:
- selective permeability, barrier/protection
- cell communication
- import and export of molecules
- cell growth and motility
Ways to influence fluidity of the cell membrane:
- shorter tails (less interaction with neighbors, more fluid)
- double bonds, kinds (unsaturated have less interactions, more fluid)
- cholesterol sits between phospholipids (sterol adds rigidity)
How is Cholesterol like other lipids?
amphipathic (polar head group), sterol
What is major lipid component of plasma membrane?
Phospholipids, with hydrophilic head and 2 hydrophobic tails, amphipathic
Where are membranes made?
ER, more phospholipids made in the cytosolic half of the bilayer
What is scramblase?
Found at ER. Catalyzes transfer of random phospholipids from one monolayer to another. Results in symmetry of growth and length.
Where does asymmetry distribution (typical in animals) occur?
Golgi lumen. Flippase catalyzes transfer of specific phospholipids to cytosolic monolayer.
What is found more on the extracellular face?
- Sphingomyelin (SM)
- Glycolipids and other carbs on sugar coating
- Phosphatidylcholine (PC)
What is found more on the cytosol face?
- Phosphatidylethanolamine (PE)
- Phosphatidylserine (PS)
- Phosphotidylinositol (PI??)
Functions of glycomatrix
- cell recognition
- cell detection
- distinguish cells (unique)
Where are glycolipids formed?
Golgi
Some categories of plasma proteins:
- transporters/channels (Ion channels, Na+ pump)
- anchors (integrins)
- receptors (PDGF)
- enzymes (protein catalysts)
What are the two ways proteins associate with the plasma membrane?
Integral membrane proteins and peripheral proteins (includes protein-attached).
What are three kinds of integral membrane proteins?
- Transmembrane
- Monolayer-associated
- Lipid-linked
