B: Fluid Mosiac Model and Membrane Protiens (15)

Question 1

How do RNA vaccines work

Answer 1

RNA vaccines trick body cells into producing a fragment of the virus, allowing the body’s immune system to respond

Question 2

What is the structure of the plasma membrane

Answer 2

Lipid bilayer made of phospholipids
Trilaminar structure

6nm thick
Micelles formed by fatty acids with one hydrophobic chain

Question 3

What are Phospholipids made off

Answer 3

Head hydrophilic (interacts with water)
Tall hydrophobic

Question 4

How do phospholipids orrinatate themselves

Answer 4

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

Question 5

Define: Amphipathic

Answer 5

Amphipathic: has both hydrophobic and hydrophilic regions

Phospholipids are amphipathic

Question 6

Define: Hydrophilic

Answer 6

Hydrophilic: molecule attracted to water molecules and tends to be dissolved by water

Question 7

Define: hydrophobic

Answer 7

Hydrophobic molecules: molecules not attracted to water or repelled by it

Question 8

Explain what fluid mosaic models are

Answer 8

Fluid: individual lipid molecules move

Mosaic: diverse particles like proteins, carbohydrates and cholesterol penetrate the lipid layer

Question 9

Why is the PM considered a fluid mosaic model

Answer 9

Viewed as 2D liquid that restricts diffusion of membrane components

Components are mobile and can easily interact

Question 10

Can lipids move within the plasma membrane

Answer 10

Yes, Move easily and latterly within the leaflet

Movement to other leaflet is difficult and slow

Question 11

Can proteins move within the membrane

Answer 11

Movement of proteins restricted

Rapid movement is spatially limited

Long range diffusion is slow

Question 12

What did the Frye-Eddin Experiment prove

Answer 12

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

Question 13

Are all membranes the same?

Answer 13

No, different membranes contain different types of lipids (giving them different fluidity) and different proteins (giving them different function)

Question 14

What is part of the inner membrane of mitochondria

Answer 14

Inner membrane of mitochondria constraints high [protein] necessary for ETC and ATP synthesis

Question 15

What is the purpose of myelin sheaths

Answer 15

Increases speed at which electrical impulses travel

Question 16

What is the structure of myelin sheaths

Answer 16

Myelin sheaths have very few types of transmembrane proteins

Consists of layers of plasma membrane wrapped around an neuron’s axon

Question 17

What are the 3 types of membrane proteins

Answer 17

1. Integral (transmembrane protein)
2. Peripheral proteins
3. Lipid anchored proteins

Question 18

What is the location and function of integral protein

Answer 18

Go from one end of membrane to other

Transport nutrients and ions
Do cell-cell communication (gap junction) and attachment

Question 19

Are peripheral proteins attatched to the membrane

Answer 19

Not physically attached, just close to membrane

Question 20

What is the purpose of lipid-anchored proteins

Answer 20

Attach to one lipid molecule in bilayer

Question 21

What is the structure of the PM

Answer 21

Biological membranes are asymmetrical

Outer leaflet contains glycolipids and glycoproteins while inner does not

Question 22

What is balance between ordered and disordered structure important for (3)

Answer 22

Mechanical support and flexibility

Membrane assembly/modification

Dynamic interactions with membrane components

Question 23

What are the 4 basic mechanisms of moving molecules across membranes

Answer 23

Simple diffusion, diffusion through channel, facilitated diffusion, active transport

Question 24

How does temp affect the fluidity of membranes

Answer 24

Warming increases fluidity - liquid crystal
Cooling decreases fluidity - crystalline gel

Most important factor of fluidity

Question 25

How does the nature of lipids affect the fluidity of membranes

Answer 25

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

Question 26

How does cholesterol affect the fluidity of membranes

Answer 26

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