Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ESA 2 SK > MR 1 The Lipid Bilayer > Flashcards

MR 1 The Lipid Bilayer Flashcards

0
Q

What is the general membrane composition?

A

40% lipid
60% protein
1-10% carbohydrate
20% water (membrane hydrated)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What is an amphipathic molecule

A

One containing both hydrophilic and hydrophobic moieties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What molecules can be phospholipid head groups?

A

Choline, amines, amino acids, sugars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How long are the most common fatty acid chains?

A

C16 and c18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What formation are double bonds in fatty acid chains?

A

Cis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do the double bonds in fatty acid chains do?

A

Introduce a kink in the chain decreasing phospholipid packing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a plasmalogen?

A

Non classical phospholipid e.g sphingomyelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why is sphingomyelin special?

A

Only phospholipid not based on glycerol. In membrane resembles other phospholipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a glycolipid?

A

Sugar containing lipid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define cerebroside and ganglioside

A

Cerebroside head group is a sugar monomer

Ganglioside head group is a sugar oligosaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What % of membrane lipid does cholesterol make up?

A

45%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What two structures can amphipathic molecules form in water?

A

Micelles and bilayers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What drives spontaneous bilayer formation in water?

A

Van der waals between hydrophobic tails

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What stabilises the cooperative structure of bilayers?

A

Non covalent forces; electrostatic and h-bonding between hydrophilic moieties and interactions between hydrophilic groups and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In what ways can lipids move in bilayers?

A

Intra-chain motion: kink formation in fatty acyl chains
Fast axial rotation
Fast lateral diffusion within plane of bilayer
Flip-flop- movement from one half of bilayer to other on one for one exchange basis(rare)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name the modes of motion of membrane proteins

A

Conformational change
Rotational
Lateral
NO FLIP FLOP

16
Q

Why don’t membrane proteins flip flop?

A

They have large hydrophilic moieties and large amounts of energy would be required for them to pass through the hydrophobic region of the bilayer

17
Q

What restricts mobility of membrane proteins?

A

Lipid mediated effects- proteins spread out into fluid phase or cholesterol poor regions
Membrane protein associations
Association with extramembranous (peripheral) proteins e.g cytoskeleton

18
Q

What are peripheral membrane proteins and how are they removed?

A

Bound to surface by electrostatic and hydrogen bonds (includes disulphide interactions)
Can be removed by changes in pH or ionic strength

19
Q

What are integral membrane proteins and how are they removed?

A

Interact extensively with hydrophobic regions of bilayer.
Cannot be removed by changes in pH or ionic strength
Removed by detergents and organic solvents that compete for the non-polar interactions in the bilayer

20
Q

How are membrane proteins translated so that they span the membrane of vesicles?

A

Using a stop transfer signal that is highly hydrophobic and remains in the ER so that the rest of the protein is translated outside of the ER in the cytoplasm

21
Q

How long is the stop transfer signal?

A

18-20AAs which is the distance to span a phospholipid bilayer

22
Q

What usually immediately follows a stop transfer signal?

A

A few basic (+ve) residues

23
Q

What are hydropathy plots used for?

A

To see how many transmembrane regions a protein has

24
Q

Why is asymmetrical orientation of proteins in membranes important?

A

Receptors for hydrophilic extracellular messengers like insulin must have recognition site facing towards extracellular space

25
Q

How do fatty acids affect membrane fluidity?

A

Double bonds in chain reduce phospholipid packing increasing fluidity

26
Q

How does cholesterol affect membrane fluidity?

A

Stabilises plasma membrane by H bonding to fatty acid chains
Abolishes endothermic phase transition of phospholipid bilayers
Reduces phospholipid packing, increasing fluidity
Reduces phospholipid chain motion decreasing fluidity

27
Q

Explain the fluid mosaic model

A

Fluid- due to hydrophobic integral components such as lipids that move laterally throughout the membrane like a fluid

28
Q

How is the shape of erythrocytes held?

A

Cytoskeleton of spectrin and actin

29
Q

What proteins in the cytoskeleton are peripheral?

A 
Actin
Spectrin
Ankyrin
Band 4.1
Adducin
30
Q

Which erythrocyte cytoskeleton proteins are integral?

A

Band 3

Glycophorin A

31
Q

What causes hereditary spherocytosis?

A

In dominant form spectrin is depleted by 40-50% so cells round up and lysis increases as RBCs have reduced lifespan

32
Q

What causes hereditary Elliptocytosis?

A

Spectrin molecules unable to form heterotetramers giving fragile elliptoid cells leading to haemolytic anaemia

ESA 2 SK (35 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions