B: Fluid Mosiac Model and Membrane Protiens (15) Flashcards
How do RNA vaccines work
RNA vaccines trick body cells into producing a fragment of the virus, allowing the body’s immune system to respond
What is the structure of the plasma membrane
Lipid bilayer made of phospholipids
Trilaminar structure
6nm thick
Micelles formed by fatty acids with one hydrophobic chain
What are Phospholipids made off
Head hydrophilic (interacts with water)
Tall hydrophobic
How do phospholipids orrinatate themselves
Lipid molecule spontaneously aggregate to buddy their hydrophobic tails in the interior, leaving their hydrophilic heads open to the water
Lipids with layers will always be in configuration that is the most stable
Define: Amphipathic
Amphipathic: has both hydrophobic and hydrophilic regions
Phospholipids are amphipathic
Define: Hydrophilic
Hydrophilic: molecule attracted to water molecules and tends to be dissolved by water
Define: hydrophobic
Hydrophobic molecules: molecules not attracted to water or repelled by it
Explain what fluid mosaic models are
Fluid: individual lipid molecules move
Mosaic: diverse particles like proteins, carbohydrates and cholesterol penetrate the lipid layer
Why is the PM considered a fluid mosaic model
Viewed as 2D liquid that restricts diffusion of membrane components
Components are mobile and can easily interact
Can lipids move within the plasma membrane
Yes, Move easily and latterly within the leaflet
Movement to other leaflet is difficult and slow
Can proteins move within the membrane
Movement of proteins restricted
Rapid movement is spatially limited
Long range diffusion is slow
What did the Frye-Eddin Experiment prove
After the fusion of 2 cells, their surface proteins are segregated, but after a short period of time, the surface proteins diffused and mingle between the combined cell
Are all membranes the same?
No, different membranes contain different types of lipids (giving them different fluidity) and different proteins (giving them different function)
What is part of the inner membrane of mitochondria
Inner membrane of mitochondria constraints high [protein] necessary for ETC and ATP synthesis
What is the purpose of myelin sheaths
Increases speed at which electrical impulses travel
What is the structure of myelin sheaths
Myelin sheaths have very few types of transmembrane proteins
Consists of layers of plasma membrane wrapped around an neuron’s axon
What are the 3 types of membrane proteins
- Integral (transmembrane protein)
- Peripheral proteins
- Lipid anchored proteins
What is the location and function of integral protein
Go from one end of membrane to other
Transport nutrients and ions
Do cell-cell communication (gap junction) and attachment
Are peripheral proteins attatched to the membrane
Not physically attached, just close to membrane
What is the purpose of lipid-anchored proteins
Attach to one lipid molecule in bilayer
What is the structure of the PM
Biological membranes are asymmetrical
Outer leaflet contains glycolipids and glycoproteins while inner does not
What is balance between ordered and disordered structure important for (3)
Mechanical support and flexibility
Membrane assembly/modification
Dynamic interactions with membrane components
What are the 4 basic mechanisms of moving molecules across membranes
Simple diffusion, diffusion through channel, facilitated diffusion, active transport
How does temp affect the fluidity of membranes
Warming increases fluidity - liquid crystal
Cooling decreases fluidity - crystalline gel
Most important factor of fluidity
How does the nature of lipids affect the fluidity of membranes
Unsaturated (c-c double bond) lipids increase fluidity
– Causes crease in fatty acid tails, stopping them from packing so close
Saturated (every c-c is a single bond) lipids reduce fluidity
– Able to pack together tighter
How does cholesterol affect the fluidity of membranes
Addition of cholesterol depends on temp on biological membrane
If added to liquid crystal membrane, fluidity will decrease
If added to crystalline gel membrane, fluidity will increase
