Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
13 Cards in this Set
- Front
- Back
|
Fxns of Plasma Membrane
|
1. outer boundary of cell
2. barrier/regulation of passage of molecules 3. mediated interaction bw cell & environment (keeps mem. potential) |
|
|
Plasma Membrane Structure
|
-phospholipid bilayer associated w/ different proteins, glycolipids, & cholesterol
-4 major phospholipids 2 outer = sphingomyelin & phosphatidylcholine 2 inner = phosphatidylserine & phosphatidylethanolamine (somtimes phosphatidylinositol) |
|
|
Role of Cholesterol
|
-temperature dependent
fxn @ high temp: -makes membrane less fluid -reduce its permeability -keeps mem together (specifically @ hydrophobic areas like wax) fxn @ low temp: -maintains mem fluidity (increase) |
|
|
Membrane Proteins
|
-lipids are structure of membrane
-proteins responsible for fxn types: -peripheral: indirectly associated, can be released w/out disrupting membrane -integral: protein w/in lipid bilayer -only released after disrupting membrane (solubolize mem w/ detergent) |
|
|
What percentage of Plasma Membrane protein?
|
~50% (can be as much as 80%)
|
|
|
Integral Proteins
|
-span the membrane
-number of membrane domains vary: -Glycophorin: passes once -Band 3: passes multiple times thru membrane -G-linked protein: passes thru 7x |
|
|
Other Membrane Proteins
|
1. GPI anchored: linked to outer membrane
2. associate w/ inner: via lipid attach, +/- charge, disulfide bonds |
|
|
Transport of Small Molecules
|
-passive diffusion
-ex: ethanol, O2, CO2, benzene -small hydrophobic molecules -high to low concentration gradient -no membrane proteins involved |
|
|
Facilitated Diffusion
|
-move along concentration gradient high to low
-involves membrane proteins -charged molecules & other large molecules can enter cells ex: glucose, aa, ions |
|
|
Active Transport
|
-moves against concentration gradient
-input of energy (ATP hydrolysis) -pumps -ex: NA-K pump |
|
|
Ion Gradient & Active Transport
|
-in GI tract, glucose moves against concentration gradient
-does not utilize ATP -utilizes Na gradient established by Na-K pump -free-ride w/ 2 Na coming in cell |
|
|
Epithelial Glucose Transport
|
-intestinal epith. transport glucose against concentration gradient
-then release glucose into blood w/ conc. gradient -apical and basal domain separated by tight jxns |
|
|
1. Glucose into cell:
2. Fxn of Tight Jxn 3. Glucose into Bloodstream |
1. via Na/K pump - sodium gradient *only on apical
2. separates 2 proteins from one another, keeps unidirectional flow of glucose 3. facilitated diffusion |
