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FMS > [FMS] CBS - lipid membrane + structure > Flashcards

[FMS] CBS - lipid membrane + structure Flashcards

1
Q

membranes are Amphipathic, what does this mean?

A

“Amphipathic” : polar head group and non-polar FA tail

OR

Hydrophilic head group, hydrophobic FA tail

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2
Q

what lipid is used as an energy store

A

triacylglycerols

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3
Q

how many classes of lipids are there, and what are they:

A

6 -
saturated and unsaturated fatty acids,
triacylglycerols, phospholipids, glycolipids and cholesterol)

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4
Q

what lipid is used as a precursor for vitamins

A

vitamin D

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5
Q

what are the examples of steroid hormones (lipids)

A

Steroid hormones ie oestrogen, testosterone, and cortisol

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6
Q

what are the examples of bile acids (lipids)

A

cholic acid

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7
Q

this questions is regarding how fatty acids are labelled - what does this labelling indicate:

18: 1 △ 9

A
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8
Q

how would you write myristic acid

A

14:0

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9
Q

how would you write plamitic acid

A

16:0

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10
Q

how would you write stearic acid

A

18:0

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11
Q

how would you write oleic acid

A

18:1△9

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12
Q

how would you write linoleic acid

A

18:2△9

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13
Q

what is a TAG made of and where is it stored

A

Triacyclglycerols (triglycerides) TAG. Ester of three fatty acids and glycerol. Stored in adipose tissue.

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14
Q

what is a fatty acid made of

A

Long-chain aliphatic carboxylic acids

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15
Q

what 3 things are phospholipids made of - what name is given to these 3?

A

Phospholipids are composed of:
- glycerol
- two fatty acids
- a phosphate containing head group.

^ these are reffered to as PHOSPHATIDYL GROUPS

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16
Q

what are phospholipids useful for and which part is hydrophobic/ hydrophilic

A

The head group and the phosphate are hydrophilic and the fatty acids are
hydrophobic. These chemical properties are key to the role in forming membranes.

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17
Q

where are fatty acids metabolised and what do they produce?

A

metabolised via beta-oxidation pathway to generate ATP

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18
Q

what does NEFA stand for in regards to fatty acids?

A

NEFA - non-esterified fatty acids

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19
Q

what are the 4 common head groups in phospholipids, and what are their respective phospholipid names?

A

choline, serine, ethanolamine and inositol. These phospholipids are called
Phosphatidylcholine PC, Phosphatidylserine, PS Phosphatidylethanolamine PE and
Phosphatidylinositol PI.

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20
Q

what 3 things is a glycolipid made from

A

Glycolipids are composed of glycerol, two fatty acids and a head group containing sugars.

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21
Q

are lipid bilayers symmetrical or asymmetrical?

A

asymmetrical -2 halves have different lipid composition

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22
Q

in lipid bilayers, out of these 4: PC, PS,SPH,PE - which faces the extracellular environment and which faces the cytosolic side?

A

PC and SPH face the extracellular environment
PS and PE face the cytosolic side

REMEMBER ‘SEEPS’ ie it SEEPS inside (SEEPs stands for PS + PS)

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23
Q

what is membrane fluidity?

A

Fluidity is the ease with which lipid molecules move about in the plane of the bilayer
important in the regulation of membrane function (e.g. movement of proteins, signalling, exocytosis)

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24
Q

what increases fluidity

A
  1. increase number of short chain FA = reduced Van der Waals interactions between FA
  2. kinks in unsaturated FA = reduced Van der Waals interactions with other lipids
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25
Q

what decreases fluidity

A

High cholesterol content restricts the random movement of polar heads, thus making lipid bilayer ‘ordered’ and decreases fluidity

(therefore highly ordered parts of lipid rafts are rich in cholesterol)

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26
Q

what is a lipid raft?

A

specialised membrane microdomain

27
Q

are lipid rafts ordered or unordered, what effect does that have on fluidity?

A

more ordered = less fluid = increased CHOLESTEROL, SPHINGOMYELIN AN DGANGLIOSIDES

28
Q

whats the function of a structural membrane protein? give an example

A

function = Cell-cell contact; attachment of cytoskeleton

example = actin, spectrin, ankyrin

29
Q

whats the function of a receptor membrane protein? give an example

A

function = Signal recognition and transmission

example = Insulin receptor, Glucagon receptor

30
Q

whats the function of an ion channel membrane protein? give an example

A

function = Maintenance of ionic gradients and transmission

example = Acetylcholine (nicotinic) receptor, GABAA receptor

31
Q

whats the function of a transporter membrane protein? give an example

A

function = Import and export of substrates

example = glucose transporters

32
Q

whats the function of an enzyme membrane protein? give an example

A

function = catalysis
example = adenylate cyclase

33
Q

what are the 3 ways membranes are organised

A

Integral (intrinsic) proteins - Transmembrane spanning domains are α-helices or β-sheets

Anchored proteins - covalent bonds with fatty acids

Peripheral (extrinsic) proteins - by ionic interactions with integral proteins or with polar head group of phospholipids

REMEMBER -

‘peripheral’ has an ‘I’ = IONIC

Anchored = covAlent

34
Q

what are 2 examples of anchored proteins?

A
  • glycolipid: enzyme alkaline phosphatase
  • fatty acyl: RAS (signalling G-protein)
35
Q

whats an example of a peripheral protein

A

spectrin: important structural protein on the cytoplasmic surface of erythrocytes interacts with other proteins such as ankyrin

36
Q

how do peripheral, anchored, and integral membrane proteins react when treated with high salt/ urea, detergent, and phospholipase (draw a table to help)

A
37
Q

what is a phospholiapse and what does it do

A

phospholipase definition = enzyme class that binds to membrane

function = selectively hydrolyse components of phospholipids

38
Q

what are the 4 phospholipases and where are they located in a phospholipid?

A

Phospholipase A1 = (PLA1)

Phospholipase A2 = (PLA2)

Phospholipase C = (PLC)

Phospholipase D = (PLD)

39
Q

what is sphingomyelin made of?

A

choline, phosphate, ceramide

40
Q

what is a ceramide made up of

A

Some lipids replace glycerol with sphingosine. Sphingosine and a single fatty acyl chain form a unit
called ceramide

THEREFORE cermaide made up of sphingosine and fstty acyl chain

41
Q

what is a GM1 ganglioside made up of

A
42
Q

what diseases is caused by the accumulation of GM2 ganglioside

A

Tay Sachs Disease (TSD)

43
Q

where does the accumulation of GM2 gangliosides occur in TSD (Tay-Sachs Disease)

A

in the lysosomes of neurones – therefore its a lysosomal storage disease

44
Q

is TSD autosomal dominant or recessive?

A

Autosomal recessive disease

45
Q

what is Zellweger syndrome?

A

complete or partial loss of peroxisomes - mutations is one of 13 PEX genes called peroxins

46
Q

which diseases is affected by the peroxisomes

A

Zellweger syndome - ZSD

47
Q

do the lipids membrane and structure quiz and then come back!!

A

https://keats.kcl.ac.uk/mod/quiz/view.php?id=7540174

48
Q

How does the phospholipid bilayer form?

A

Spontaneously forms bi-layer in aqueous environment.

49
Q

what makes lipid bilayers asymmetrical?

A

Phosphatidylcholine and sphingomyelin face the extracellular environment.

Phosphatidylserine and phosphatidylethanolamine face the cytosolic side.

REMEMBER: SEEPS inside (PE, PS = inside on cytosol)

50
Q

What are 5 properties of lipid rafts?

A
  • They have specialised membrane microdomain
  • More ordered – less fluid
  • Increased level of cholesterol, sphingomyelin and gangliosides
  • Allows close interaction between receptors and signalling molecules
51
Q

What disease occurs when the metabolism of GM2 is deficient?

A

Tay Sachs Disease

52
Q

What disease occurs when the metabolism of GlcCer is deficient?

A

Gaucher’s disease

53
Q

What disease occurs when the metabolism of Cer is deficient?

A

Farber disease

54
Q

What is a diagnostic observation of TSD?

A

Infantile TSD patients have a characteristic observation of a cherry-red spot

55
Q

what is an integral protein

A

Integral (intrinsic) proteins – embedded in lipid bilayer, most span the entire bilayer. Transmembrane spanning domains are α-helices or β-sheets

56
Q

what is an anchored protein

A

Anchored proteins – anchored to membrane by covalent bonds with fatty acids

57
Q

what is a peripheral protein

A

Peripheral (extrinsic) proteins – attach to membrane surface by ionic interactions with integral proteins or with polar head group of phospholipids

58
Q

what 3 components make up a ‘phosphatidyl’ group

A

Phosphate, glycerol and fatty acid

59
Q

whats the structure of steroids

A

multi-ring hydrophobic region and a hydrophilic
region.

60
Q

what is cholesterol made from

how can it be synthesised?

A

Cholesterol is a steroid that forms part of membranes and is the precursor of steroid
hormones.

It can be synthesised de novo or obtained from diet.

61
Q

Where does PLA1 cleave?

A

SN-1 position

Act between 1st fatty acid and glycerol

62
Q

Where does PLA2 cleave?

A

SN-2 position

Acts between second fatty acid and glycerol
Erachadonic acid

63
Q

Where does PLD cleave?

A

Act between phosphate and phospholipid head group

64
Q

Where does PLC cleave?

A

Acts between glycerol and phosphate

FMS (33 decks)

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