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icpp > ICPP 1 Membrane Bilayer - Lipids > Flashcards

ICPP 1 Membrane Bilayer - Lipids Flashcards

1
Q

What are functions of the membrane?

A

Highly selective barrier
Control of enclosed electrochemical environment
Communication
Recognition
Signalling
Adhesion protein
Immune surveillance - communication
Signal generation to response to stimuli

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2
Q

What is the membrane composition by dry weight?

A

40% lipid
60% protein
1-10% carbs

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3
Q

How much of membrane weight is water?

A

20%

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4
Q

Role of water in membranes

A

Interacts with charged/polar regions + stabilises lipid head regions

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5
Q

What are the types of lipids?

A

Glycolipids
Cholesterol
Phospholipids - saturated + unsaturated

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6
Q

Types of unsaturated chains

A

Cis - kink
Trans - straight leg

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7
Q

What type of chain will make the membrane more fluid and why?

A

Cis unsaturated chain
Less tightly packed together due to kinks

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8
Q

Amphipathic meaning

A

Includes both hydrophobic + hydrophilic parts

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9
Q

Composition of phospholipid

A

Hydrophilic phosphate head + polar group
Glycerol backbone
Hydrophobic fatty acid tails

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10
Q

What type of reaction is between the fatty acid tails + glycerol back bone in phospholipids?

A

Esterification reaction

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11
Q

What enables phospholipid head + tails to rotate?

A

Glycerol residual has single bonds

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12
Q

Types of polar groups attached to the phosphate head in phospholipids

A

Amines
Amino acids
Choline - most common
Inositol - source of secondary messanger

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13
Q

What makes phospholipids optimally energetically stable?

A

External hydrophilic head
Internal hydrophilic tails

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14
Q

What is a sphinogomyelin?

A

Phospholipid without glycerol backbone
Has a sphingosine molecule instead

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15
Q

How are sphinogomyelin synthesised?

A

Bringing together a fatty acid chain + sphingosine molecule

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16
Q

What do sphingosine molecules have?

A

Serine residual -NH group

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17
Q

What can be the head group in sphinogomyelins?

A

Choline
Ethanolamine

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18
Q

What are the fatty acid chains mainly in sphinogomyelins?

A

Mainly saturated FA
If unsaturated FA > trans > no kink > closer packing

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19
Q

Function of sphinogomyelins

A

Membrane protein orientation
Formation of lipid rafts

20
Q

Composition of sphinogomyelins

A

Head group - choline or ethanolamine
Sphingosine molecule
Fatty acids - mainly saturated

21
Q

Composition of glycolipids

A

No phosphate had
No glycerol backbone - sphingosine molecule instead
Fatty acid chains

22
Q

Where are glycolipids located?
What for?

A

Only on external membrane for signalling

23
Q

Classes of glycolipids

A

Cerebrosides
Gangliosides

24
Q

Head group in cerebroside

A

Glucose
Galactose

25
Q

Where is there a high concentration of sphinogomyelins?

A

Myelin sheath

26
Q

Where is there a high concentration of cerebrosides?

A

Myelin sheath
Nervous system

27
Q

Function of cerebrosides

A

Stabilises membrane
Cell to cell recognition
Form basis of blood group - antigens on RBCs
Lipid raft formation

28
Q

What is connected to the head group in gangliosides?

A

Oligosaccharide chain

29
Q

Function of gangliosides

A

Cell-cell signalling
Immune system - important in CNS
Lipid raft formation

30
Q

Where are gangliosides on membranes?

A

Extend out from cell surface

31
Q

What are steroids derived from?

A

Cholesterol

32
Q

Composition of cholesterol

A

-OH head - hydrophilic
Non-polar hydrocarbon tail - hydrophobic

33
Q

Function of cholesterol

A

Membrane fluidity control
Lipid raft formation
Extending temp rang of membrane

34
Q

Relationship between permeability of membrane + structural integrity

A

Reciprocal
Increase in permeability = decreased in structural integrity + vice versa

35
Q

List the ways lipids can move

A

Fast axial rotation
Fast lateral diffusion
Protrusion
Wave 3D undulations
Flip flop

36
Q

Describe fast axial rotation

A

Whole lipid spins on head-tail axis
In circles

37
Q

Describe fast lateral diffusion

A

Lipids move randomly side to side through bilayer

38
Q

Describe protrusion

A

Bobbing up + down on vertical axis

39
Q

Describe wave 3D undulations

A

Like Mexican wave

40
Q

Describe flip flop movement

A

Lipid flips upside down

41
Q

What does adding unsaturated phospholipids to the membrane do?

A

Increases fluid using due to cis chains
Less close packing
Gel/fluid state

42
Q

What does adding unsaturated phospholipids to the membrane do?

A

Increased membrane stability
Acts as a buffering molecule - extends temp. range

43
Q

What are lipid rafts?

A

Areas of organised/specialised distribution of lipids

44
Q

Components of lipid rafts

A

Cholesterol
Sphinogomyelins
Saturated glycolipids

45
Q

Function of lipid rafts

A
  • Provides more stable environment for signalling proteins
  • Stabilises + organises proteins
  • Acts as organising domain for receptors or signalling molecules
  • Optimises kinetic interaction for signal transduction
46
Q

What features does the components of lipid rafts allow?

A

Strong interaction > tight packing > decreased movement + fluidity

47
Q

What is there a reduced amount of in lipid rafts?

A

Unsaturated chain phospholipids

icpp (18 decks)

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