Chapter 11: Membrane Structure Flashcards
Membrane Composition
lipids and proteins
Integral proteins
directly attached to membrane
Peripheral
loosely associated with membrane
The rearrangement of the phospholipid bilayer favors what?
- repair of damage
- formation of a closed compartment ( which is more favorable)
Liposomes structure
phospholipid bilayer and aqueous interior
How can phospholipids move?
- lateral diffusion
-flexion
-rotation
-flip-floping sides ( rarely occurs)
Phospholipid affect on membrane fluidity
-fatty acid chain length (shorter = more fluid)
-fatty acid
chain saturation (cis double bond = more fluid)
Sterol affect on membrane fluidity
Cholesterol ( high concentration more fluid)
- if most fatty acids are unsaturated then cholesterol creates less fluidity
Temperature affect on membrane fluidity
high temp ( high fluidity)
low temp ( more rigid)
is cholesterol amphipathic
yes
What is the pattern of mature membranes
asymmetrical
1st step of membrane synthesis
in the smooth ER phospholipids are added no the cytosolic face
2nd Step of membrane synthesis
scramblases randomly flip phospholipids from one face of the membrane to the other in the ER
3rd Step of membrane synthesis
Flippases move specific phospholipids from the extracellular face to the cytosolic face in the Golgi. Floppases move phospholipids from the cytosolic face to the extracellular face of the Golgi
Where do glycolipids obtain their sugar?
inside the Golgi
How can integral membrane proteins be removed from membranes?
using detergents
What happens when multiple amphipathic alpha helices associate?
form a hydrophilic pore ( integral membrane protein)
What can a large curved beta sheet form?
beta barrel that spans the membrane
Beta barrel structure
hydrophobic exterior and water filled interior (integral membrane protein)
What do detergents do?
disrupt hydrophobic associations
Properties of detergents
-Amphipathic
-Single hydrophobic chain
-Monolayer micelles
Glycoprotein
protein with short, covalently attached oligosaccharide
Proteoglycan
protein with one or more long oligosaccharides
Glycolipid
lipid with covalently attached oligosaccharide
Carbohydrate layer of cell surface composition
Glycoprotein, Proteoglycan, Glycolipid
Carbohydrate later of cell surface function
protection from chemical and mechanical damage
- cell to cell recognition
Ligands for lectins
proteins that bind oligosaccharide chains
Glycocalyx
carbohydrate layer
What is lectin binding responsible for?
recruitment of white blood cells to site of infection
Cell Cortex
framework of proteins that attaches to membrane proteins, restricting their mobility
What do tight junctions preserve?
the asymmetric distribution of membrane proteins
