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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
Why are membranes important?
Compartmentalisation Highly selective barriers Have sensors (mainly proteins) to respond to internal + external conditions
26
What’s the fluid mosaic model?
Phospholipid bilayer = fluid matrix and 2D solvent Lipids + proteins = rotational and lateral movement
27
What are the two classes of proteins in phospholipid bilayer?
Peripheral proteins (extrinsic) Integral proteins (intrinsic)
28
What can alter fluidity in particular parts of cell membrane?
Cholesterol
29
Where are new phospholipids synthesised?
By enzymes at ER facing the cytosol They use fatty acids available in cytosol
30
Where are new phospholipids released in ER?
Into outer leaflet of ER bilayer Lipids are then transferred to other side by flippases
31
What are flippases?
Enzymes that can move phospholipids between leaflets Some are selective for particular phospholipids
32
What are the different flippase mechanisms?
Pore model = channel moves hydrophilic head to other side ‘Slip-pop’ model = protein jolts
33
Where does membrane synthesis take place?
In ER New membrane transported to other parts of cell through series of vesicle budding + fusion
34
What’s vesicle trafficking?
When bits of membrane pinch off ER to form vesicles and then fuse with other membranes
35
What’s endocytosis?
Movement of materials into cells via membrane bound vesicles
36
What’s endocytosis important in?
Immune response
37
What are lipid rafts?
Organising centre for vesicle trafficking and cell signalling
38
Why are there membrane proteins?
Molecules require specific transport to diffuse across a lipid membrane Transmembrane signalling
39
What do membrane associated proteins usually contain?
Domains that selectively bind to phospholipids - compartment-specific association
40
What’s PH?
Pleckstrin homology domains
41
What happens when PH domain is removed?
Alters a protein’s binding properties
42
Give an example of lipids-linked proteins:
GPI-anchors
43
What are protein-attached proteins important for?
Signal transduction
44
What are protein-attached proteins?
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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