Chapter 10: Membrane Structure Flashcards
Membranes are essential for what?
Cell viability
Membranes are used to establish what that have distinct and diverse functions?
Compartments
Name three functions of membranes
- Synthesizing ATP
- Transmitting electrical signals
- Acting as sensor to extracellular cues
All biological membranes have a common what?
General structure
Basic structure of all cellular membranes include what?
Lipid molecules and membrane associated proteins
The most abundant membrane lipids are what?
Phospholipids
What are phospholipids composed of?
A polar (water loving) head group and two hydrophobic (water fearing) hydrocarbon tails
The nonpolar tails of phospholipids vary in their what?
Length (13-24 carbons)
One of the hydrocarbon tails of a phospholipid may contain one or more whats which impacts lipid packing within the bilayer?
Double bonds
The differences in the length of the tail plus the number of double bonds influence what?
The fluidity of the membrane
What are these structures?
Phospholipids
What are the main phospholipids?
Phosphoglycerides
Phosphoglycerides contain what kind of backbone?
A 3 carbon glycerol backbone
In a phosphoglyceride, 2 carbons of the glycerol are linked to what?
Fatty acid tails
In a phosphoglyceride, the 3rd carbon is linked to a phosphate group which is linked to a what?
Head group
Give an example of a phosphoglyceride
Phosphotidylcholine
What is this structure?
Lipid Bilayer
Identify structure
Phosphatidylethanolamine
What is this structure?
Cholesterol
What is A and B?
A: Lipid Micelle; B: Lipid Bilayer
What is a rigid ring structure attached to a polar hydroxyl head group and short nonpolar hydrocarbon tail?
Cholesterol
What packs in between phospholipids close to the nonpolar head groups?
Cholesterol
How many cholesterol molecules are present per phospholipid?
One cholesterol molecule present per phospholipid
Cholesterol has an impact on what property of the lipid bilayer?
The permeability-barrier properties of the bilayer
Cholesterol makes the bilayer less permeable to what?
Small water soluble molecules
Yes or No: Does cholesterol change the fluid properties of the membrane?
No
Membrane fluidity is influenced by two factors
Composition and temperature
Membranes with short hydrocarbon tails/multiple double bonds are more fluid at lower temperatures than membranes composed of what? Due to differences in what?
Long, saturated hydrocarbon tails due to differences in phospholipid packing
Which one has unsaturated hydrocarbon chains with cis-double bonds or saturated hydrocarbon chains?
A: unsaturated hydrocarbon chains with cis-double bonds B: saturated hydrocarbon chains
Which are thinner: Membranes composed of unsaturated phospholipids or membranes composed of saturated phospholipids?
Unsaturated phospholipids
Where does most of the movement in a layer of phospholipid occur?
Within the plane of each monolayer
Lipids rotate on their what?
Axis
Lipids exchange positions with neighboring lipids by what?
Lateral diffusion
Which motion in the lipid layer occurs most often?
A: Lateral diffusion
Which motion in the lipid layer is rare?
B: Flip-flop
Lipids molecules in the plasma membrane associate in specialized lipid subdomains referred to as what?
Lipid rafts
What regions are enriched with sphingolipids and cholesterol and are involved in organizing membrane proteins?
Lipid rafts
Lipid composition of membrane proteins differ how?
From organism to organism and organelle to organelle
Cholesterol is absent from what organism?
E. coli
What organism’s plasma membrane is composed primarily of phosphotidylethanolamine?
E. coli
A typical cell membrane can contain upwards of how many different lipid types that vary in their head groups, hydrocarbon chain length and saturation?
1, 000
The two leaflets of a lipid bilayer differ in their what?
Composition
What are sugar modified lipids?
Glycolipids