Membrane structure and function

Question 1

How many membranes are there in a eukaryotic membrane?

Answer 1

2, inner and outer

Question 2

Describe the fluid mosaic model: (4)

Answer 2

Lipid bilayer 5nm
Protein molecules
Cholesterol

All fluid within each other

Question 3

What are the 3 main components of membrane and what are their roles?

Answer 3

Lipids - barrier, signalling, compartmentalisation
Proteins - channels, Adhesion, Receptors, cytoskeleton link
Carbohydrates - cell identity and recognition

Question 4

What type of lipids are membrane lipids?

Answer 4

Amphipathic

Question 5

How is the lipid bilayer held together?

Answer 5

Van der Waals bonds between fatty tails

Question 6

What are the 3 structures lipids can form?

Answer 6

Micelles, bilayers or liposomes

Question 7

How do detergents work?

Answer 7

Form micelles and disrupt fatty acids

Question 8

What are the 3 classes of lipids?

Answer 8

Phospholipids
glycolipids
cholesterol

Question 9

Where are lipids made and where are they destroyed?

Answer 9

Made: Smooth ER
Destroyed: Lysosome

Question 10

What are the main types of phospholipids?

Answer 10

Phosphoglycerides

Question 11

What is the structure of a phosphoglyceride?

Answer 11

Choline/serine
Phosphate
Glycerol
Hydrocarbon tail x2

Question 12

What are the 4 different types of heads in phospholipids?

Answer 12

Phosphatidyl-ethanolamine
Phosphatidyl-serine
Phosphatidyl-choline - most common
Sphingomyelin

Question 13

What are the properties of phospholipid tails? (6)

Answer 13

Fatty acids
Hydrocarbon chain ending in carboxylic acid
Chemical formula: CH3(CH2)nCOOH
14-24 carbon chain length
Common 16C & 18C
Saturated or unsaturated

Question 14

What is composition of phospholipids in the inner and outer membranes?

Answer 14

Phosphatidyl-ethanolamine: Inner only
Phosphatidyl-serine: Inner only (negatively charged)
Phosphatidyl-choline : both membranes
Sphingomyelin: both membranes

Question 15

What is the name of the 3 enzymes that allow phospholipids to switch membranes?

Answer 15

Flippase
Floppase
Scramblase

Question 16

How can we tell if a cell is going to do due to its membrane structure?

Answer 16

Phosphatidyl-serine: Inner only

It appears on the outer membrane

Question 17

Where are glycolipids found?

Answer 17

Outer membrane

Question 18

What are the key properties of a glycolipid? (5)

Answer 18

Sphingolipid base
1 or more sugar residues
5/6C rings
No phosphate
Neutral or acidic

Question 19

What is the size of cholesterol?

Answer 19

1.5nm

Question 20

What is cholesterols role?

Answer 20

Stiffen the membrane and provide structure

Question 21

What is the role of sterols in the membrane?

Answer 21

Straighteners