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Week 7 - 12 > Lipids And Cell Membranes > Flashcards

Lipids And Cell Membranes Flashcards

1
Q

What are lipids like in water?

A

Low solubility

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2
Q

Give examples of lipids:

A

Phospholipids

Fats

Sterols

Vitamins

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3
Q

What do lipids do?

A

Sources of energy

Form membranes

Participate in cell signalling

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4
Q

What are fatty acids?

A

Principle store of energy

Rarely free in the body

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5
Q

Structure of fatty acids:

A

Carboxyl group with long hydrocarbon chain

Naturally occurring = even number of carbons

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6
Q

What are fatty acids usually part of if not free in the body?

A

Part of lipid molecule

Complexed to carrier protein

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7
Q

Difference between fatty acid chain lengths:

A

Short + medium chain = absorbed into bloodstream

Long chain = can’t be absorbed

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8
Q

Saturated fatty acids:

A

No double bonds

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9
Q

Unsaturated (cis) fatty acids:

A

Double bond

Kink in chain

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10
Q

Unsaturated (trans) fatty acids:

A

Double bond

No kink in chain

Dangerous to eat

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11
Q

16:0

A

Saturated

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12
Q

18:1

A

Unsaturated

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13
Q

20:4

A

Polyunsaturated

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14
Q

How are double bonds numbered as in fatty acids?

A

Δ

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15
Q

What are double bonds like in polyunsaturated fatty acids?

A

Never conjugated

Separated by -CH2

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16
Q

Structure of omega fatty acids:

A

Unsaturated

Numbered as first c-c bond from methyl end

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17
Q

Give examples of sterols:

A

Bile acids

Steroid hormones

Vitamins

Cell membranes

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18
Q

What do inherited disorders in lipid pathways result in?

A

Defects in enzymes which metabolise lipids - lead to lipids accumulation

19
Q

Which lipids are found in membranes?

A

Phospholipids

Glycolipids

Sterols

20
Q

Structure of phospholipids:

A

Polar head group

Glycerol backbone

Fatty acid chains

21
Q

What is included in polar head group of phospholipid?

A

Choline and Phosphate

22
Q

Structure of glycolipids:

A

Sphingosine core

23
Q

What are membrane proteins usually like?

A

Amphipathic - conflicting properties e.g. both hydrophilic and hydrophobic elements

24
Q

What results in the lipid bilayer?

A

Hydrophilic head faces water

Hydrophilic tails shielded from water and lie next to each other

25
Q

Why are membranes important?

A

Compartmentalisation

Highly selective barriers

Have sensors (mainly proteins) to respond to internal + external conditions

26
Q

What’s the fluid mosaic model?

A

Phospholipid bilayer = fluid matrix and 2D solvent

Lipids + proteins = rotational and lateral movement

27
Q

What are the two classes of proteins in phospholipid bilayer?

A

Peripheral proteins (extrinsic)

Integral proteins (intrinsic)

28
Q

What can alter fluidity in particular parts of cell membrane?

A

Cholesterol

29
Q

Where are new phospholipids synthesised?

A

By enzymes at ER facing the cytosol

They use fatty acids available in cytosol

30
Q

Where are new phospholipids released in ER?

A

Into outer leaflet of ER bilayer

Lipids are then transferred to other side by flippases

31
Q

What are flippases?

A

Enzymes that can move phospholipids between leaflets

Some are selective for particular phospholipids

32
Q

What are the different flippase mechanisms?

A

Pore model = channel moves hydrophilic head to other side

‘Slip-pop’ model = protein jolts

33
Q

Where does membrane synthesis take place?

A

In ER

New membrane transported to other parts of cell through series of vesicle budding + fusion

34
Q

What’s vesicle trafficking?

A

When bits of membrane pinch off ER to form vesicles and then fuse with other membranes

35
Q

What’s endocytosis?

A

Movement of materials into cells via membrane bound vesicles

36
Q

What’s endocytosis important in?

A

Immune response

37
Q

What are lipid rafts?

A

Organising centre for vesicle trafficking and cell signalling

38
Q

Why are there membrane proteins?

A

Molecules require specific transport to diffuse across a lipid membrane

Transmembrane signalling

39
Q

What do membrane associated proteins usually contain?

A

Domains that selectively bind to phospholipids - compartment-specific association

40
Q

What’s PH?

A

Pleckstrin homology domains

41
Q

What happens when PH domain is removed?

A

Alters a protein’s binding properties

42
Q

Give an example of lipids-linked proteins:

A

GPI-anchors

43
Q

What are protein-attached proteins important for?

A

Signal transduction

44
Q

What are protein-attached proteins?

A

They are proteins that don’t bind to the membrane itself but is associated with membrane due to their receptor

Week 7 - 12 (38 decks)

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