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cell biology > lipids and membranes > Flashcards

lipids and membranes Flashcards

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1
Q

what are non-essential fatty acids?

A

synthesised by your body

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2
Q

give examples of non-essential fatty acids

A

oleic acid
palmitic acid
stearic acid

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3
Q

what are essential fatty acids?

A

fatty acids that must be obtained from the diet

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4
Q

give examples of essential fatty acids

A 
omega 6 (linoleic acid)
omega 3 (alpha linoleic acid)
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5
Q

where can you get linoleic acid from?

A

sunflower or olive oil

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6
Q

where can you get alpha linoleic acid from?

A

seeds and nuts

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7
Q

which end of the fatty acid is the omega end?

A

methyl end

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8
Q

what is another name for omega-9?

A

oleic acid

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9
Q

why is oleic acid considered a non-essential fatty acid?

A

we have the desaturase enzyme to induce the double bond at carbon 9

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10
Q

why are fatty acids an efficient store of energy?

A

1g fatty acid = 6g of glycogen

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11
Q

how are triglycerides stored?

A

fat droplets

monolayer

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12
Q

how are triglycerides used when energy is needed by the body?

A

hydrolysis splits it into glycerol and three fatty acids
FAs bind to albumin
carry it to the muscles which then use it for energy

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13
Q

whats a sphingolipid?

A

like a triglyceride, but a serine instead of glycerol and two fatty acids instead of one

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14
Q

what is the structure of a glycolipid?

A

two long hydrocarbon chains attached to one or more sugars

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15
Q

what do glycolipids do?

A

surface of all plasma membranes
needed in cell to cell contact
protects cell from a hostile environment

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16
Q

what’s the difference between glycerophospholipids and sphingolipids?

A

spingolipids are more saturated - straighter and pack more tightly together

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17
Q

what happens when you add cholesterol to glycerophospholipids?

A

makes the membrane less fluid

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18
Q

what happens when you add cholesterol to sphingolipids?

A

makes the membrane more fluid

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19
Q

what are lipid rafts?

A

when sphingolipids and cholesterol self-associate to creat lipid rafts which membrane proteins can dock

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20
Q

do glycerophospholipids tend to be on the inside or outside of the membrane and why?

A

inside because they’re negative

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21
Q

do sphingolipids tend to be on the inside or outside of the membrane?

A

outside

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22
Q

what is cholesterol a precursor to?

A

bile salts
vitamin D
steroids
sex hormones

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23
Q

where is cholesterol converted to bile?

A

in the liver

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24
Q

how is cholesterol carried around the blood?

A

lipoproteins

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25
Q

what causes atherosclerosis?

A

high levels of LDL

26
Q

what is omega 6 a precursor to?

A

arachidonic acid

27
Q

what is omega 3 a precursor to?

A

EPA

28
Q

what is COX-2?

A

an enzyme necessary for conversion of arachidonic acid to prostaglandins

29
Q

what can arachidonic acid and EPA make?

A

paracrines
leukotriences
prostaglandins
thromboxanes

30
Q

what does amphillic mean?

A

water hating and water loving

31
Q

what are the zones of a bilayer?

A

two hydrophillic regions with a hydrophobic region int he middle

32
Q

how are fatty acyl chains made?

A

ketosynthase - joins 2 carbon compounds together and removes CO2

reduction reactions via ketoreductase, dehydratase and enoylreductase

thioesterase forms fatty acid

33
Q

what does saturated mean?

A

no double bonds

34
Q

what does unsaturated mean?

A

double bonds

35
Q

what is oleic acid?

A

18C compound
monounsaturated
omega 9

36
Q

whats the difference between cis and trans oleic acid?

A 
cis = kinked
trans = straight, made in industry for food
37
Q

what is oleic acid made from?

A

stearic acid using desaturase

38
Q

what is linoleic acid?

A

omega 6 polyunsaturated

39
Q

what is alpha linoleic acid?

A

omega 3 fatty acid

40
Q

what are paracrines?

A

short-lived, near-acting, cyclic FA signalling molecules

mediators of inflammation, pain, fever, immunosuppression, clotting, blood vessel constriction etc

41
Q

name paracrines and where they’re made?

A

o Leukotrienes – made by leukocytes
o Prostaglandins – made in all tissues
o Thromboxanes – made by platelets

42
Q

explain how paracrines are made?

A

phospholipase converts membrane lipids to O3/6

O3 –> EPA
O6 –> arachidonic acid
by elongases and desaturases

COx2 then converts these to paracrines

43
Q

what drugs target COX2?

A

NSAIDs like aspirin, ibuprofen and indomethicin

44
Q

why is omega 9 non-essential fatty acid?

A

we have the desaturase enzyme to break this down

45
Q

how are fatty acids stored?

A

triglycerides

46
Q

describe the structure of triglycerides?

A

one molecule of glycerol with 3 fatty acids attached to it

47
Q

how are triglycerides used for energy?

A
  • Triglyceride split into Glycerol and Fatty acids via hydrolysis
  • FAs bind to Albumin which transports the FAs to muscle cells
  • Muscle cell takes up the FAs and uses it for energy
48
Q

what are the 3 main membrane lipids?

A
  • Glycerophospholipids
  • Sphingolipids (includes glycolipids)
  • Cholesterol
49
Q

describe the structure of glycerophospholipids

A

glycerol linker attaches to 2 fatty acids - one is straight and one is kinked
3rd attachment is a phosphate group with a choline head

50
Q

describe the structure of sphingolipids

A
  • Serine “linker”
  • Attaches to 2 Fatty acid tails (non polar)
  • 3rd attachment can be to any functional group (polar)
51
Q

what are glycolipids and what do they do?

A

type of sphingolipid

protect cell from hostile environment

52
Q

what’s the difference between glycerophospholipids and sphingolipids?

A

glycero - more double bonds so its shorter and more kinked

sphingo - fully saturated

53
Q

what does adding cholesterol do to glycerophospholipids?

A

makes it more densely packed, less fluid and less permeable

54
Q

what does adding cholesterol to sphingolipids do?

A

more fluid bc it pushes them apart

55
Q

how are lipid rafts made?

A

• Sphingolipid and cholesterol self-associate to create fluid lipid rafts into which different functional membrane proteins can “dock.”

56
Q

why do membrane lipids make a bilayer?

A

membrane lipids are cylinders. In water, they maximise the packing by forming a sheet that is also a bilayer. Acyl chains interact with each other and the head groups interact with the water

57
Q

why do fatty acids make micelles?

A

Fatty acids are conical. When they’re in water, they self-associate because the hydrocarbon tail is hydrophobic and the carboxyl head is hydrophilic

58
Q

what is a liposome?

A

membrane lipid ball with no other molecules

59
Q

how are liposomes used?

A

used to study behaviour of lipid membranes (and, because they are readily taken up by cells, have also been used to deliver drugs and DNA to patients)

60
Q

what does fluidity of the membrane refer to?

A
  • Acyl chains can flex
  • Rotation of membrane lipids in the bilayer
  • Diffuse laterally within the leaflet
  • ”Flip Flop” (rare) – involves hydrophilic head moving through hydrophobic tails
61
Q

what does mosaicity refer to?

A

how many membrane proteins are embedded in the bilayer

cell biology (17 decks)

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