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Biochem K > Lipids > Flashcards

Lipids Flashcards

1
Q

Which are the classes of lipids?

A

1) Simple lipids -Includes fats and waxes which are esters of fatty acids with various alcohols.
2) Complex lipids -are esters of fatty acids containing groups in addition to an alcohol and one more fatty acid. they can be further divided into 3 groups.
3) Precursor derived lipids

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2
Q

Which are the three groups the Complex lipids?

A
  • Phospolipids (lipids containing an alcohol and a phosphoric acid residue)
  • Glycolipids, or Glycosphingolipids: contain a Fatty acid, a Sphingosine and a carbohydrate.
  • Other complex lipids : such as Sulfolipids + lipoproteins etc.
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3
Q

What are neutral Lipids?

A

Uncharged lipids. Examples are : Acylglycerols, cholesterol and cholesteryl.

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4
Q

Which is the transport form of fatty acids in Plasa?

A

Free fatty acids, in body their found mainly as esters.

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5
Q

Which Fatty acids end with anoic in their names?

A

Saturated fatty acids.

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6
Q

How are the carbons of fatty acids named?

A

from carboxyl carbon as nr1

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7
Q

how many double bonds do saturated fatty acids have?

A

None

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8
Q

What are Eicosanoids?

A

compounds derived from eicosa (20 carbon) polyenoic fatty acid.
these comprise: Prostanoids, Leukotrienes (LTs) and Lipoxins (LXs)

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9
Q

Prostaglandins, prostacyclins and thromboxanes are…?

A

Prostanoids

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10
Q

which type of prostaglandin has a keto group in position 9

A

PGE (E type)

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11
Q

which fatty acids have anti inflammatory effects?

A

e3 Long chain fatty acids such as: alpha linoleic (ALA), EPa and DHA.

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12
Q

which compound is important as an intermediate in the synthesis of triacylglycerols and phosphoglycerols?

A

Phosphatedic acid. it is however not found in great quantities in tissues.

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13
Q

which are the most abundant phospholipids of the cell membrane?

A

Lecithins, glycerophospholipids containing choline.

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14
Q

What is the role of Dipalmitoyl lecithin?

A

Its a very effective surface-active agent and a major constituent of the surfactant, preventing adherence due to surface tension of the inner surfaces of the lungs.

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15
Q

What is the consequence of the absence of Dipalmitoyl in the lungs of infants?

A

causes respiratory distress syndrome.

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16
Q

Where does most phospholipids have their saturated acetyl radicals and their unsaturated acetyl radicals, respectively?

A
  • Saturated acetyl radicals at the sn1 position

- Unsaturated acetyl radicals on the sn2 position of the glycerol.

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17
Q

Which lipid is involved in Apoptosis?

A

Phosphatidylserine.

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18
Q

Which lipids can be found in the cell membrane?

A
  • Phosphatidylethnolalamine (cephalin)
  • Phosphatidylserine
  • Phosphatidylcholine
  • Cholesterol
  • Sphingomyelin (in outer leaflet)
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19
Q

What are lipid rafts and which lipids are particularly abundant there?

A

They are specialized areas of the plasma membrane where sphingomyelins are found.

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20
Q

Where are Sphingomyelins found and in which processes are they involved?

A
  • Lipid rafts and myeline sheaths surrounding nerve fibers.

- Cell signalling and Apoptosis

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21
Q

What does sphingomyelins yield upon hydrolysis?

A

A fatty acid, Phosphoric acid, choline and sphingosine.

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22
Q

Sphingosine + Fatty acid = ?

A

Ceramide (also found in glycosphingolipids)

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23
Q

What role does the Phosphorylated Phosphatidylinositols?

A

They are minor components of the cell membrane and important components of both cell signalling and membrane trafficking.

24
Q

Where can the Phosphotidylinositols have 1,2 or 3 phosphates attached?

A

Onto their inositol ring.

25
Q

cleavage of phosphatidylinositol 4,5-biphosphate (PiP2)

A

results in a Diaglycerol and an inositol tris-phosphate as a result of hormone stimulation.
Both of these acts as internal signals or secondary messengers.

26
Q

What gives rise to cardiolipin?

A

Phosphatidic acit to Phosphatidyl glycerol to cardiolipin.

27
Q

Where can cardiolipin be found? role?

A

Only in mitochondria where its presence is essential for the mitochondrial function.

28
Q

What is the result of decreased levels of Cardiolipin or alterations of its structure/metabolism?

A
  • mitochondrial dysfunction
  • Heart failure
  • Hypothyroidism
  • Barth syndrome
29
Q

Which lipids are intermediates in the metabolism of Phosphoglycerols?

A

Lysophospholipids.

30
Q

Where is Lysophosphatidylcholine important?

A

in the metabolism and interconversion of phospholipids.

Also found in Oxidised lipoproteins. promotes atherosclerosis.

31
Q

How do the Plasmalogens differ from Phosphatidylethanolalamine?

A

Looks the same but has an ether link on the sn-1 carbon instead ester as is found in acylglycerols.
In some cases choline, serine or inositol may be substituted for ethanolalamine as well.

32
Q

Where are the Glycolipids (glycosphingolipids most commonly found?

A

in the outer leaflet of the plasma membrane where they contribute to formation of glycocalyx by providing cell surface carbohydrates.

33
Q

Lipids which have an attached carbohydrate or carbohydrate chain are?

A

Glycolipids.

34
Q

Where can Galactosylceramide be found the most?

What does it contain which is characteristic for it?

A

its a major glycosphingolipid of the brain and other nervous tissue.
It contains C24 fatty acid, eg. cerebronic acid.

35
Q

What are Gangliosides?

A

Complex glycosphingolipids derived from glycosylceramide that in addition contain one or more molecules of sialic acid.

36
Q

Function of Gangliosides?

A

cell-cell recognition and communication as well as receptors for hormones and bacterial toxins such as cholera toxin.

37
Q

What is the simplest ganlioside, GM3 composed of?

A

ceramide, one molecule of galactose and one molecule of NeuAc.

38
Q

What is the more complex GM1 derived from

A

GM3

39
Q

Role of GM3?

A

receptor in human intestine for cholera toxin.

40
Q

What steroids is cholesterol a precursor for?

A
  • Bile acid
  • Adrenocortical hormones
  • sex hormones
  • vitamin D
  • cardiac glycosides.
41
Q

What conformation does all the naturally occurring steroids have?

A

Chair conformation, -the more stabile conformation.

42
Q

what conformation is usually the BC junction

A

trans

43
Q

beta bonds are shown as?

A

uppstickande raka linjer

44
Q

Cholesteryl ester is?

A

A form of cholesterol where the position 3 hydroxyl group is esterified with a long fatty acid chain. –> only found in animals.

45
Q

How does Ergosterol react to exposure to UV light?

A

its B ring opens and vitamin D2 forms.

46
Q

how are polyprenoids related to cholesterol.

A

Theyre not steroids but they’re formed just like cholesterol from five carbon isoprene units.

47
Q

Obiquinone and dolichol are?

A

Polyprenoids.

48
Q

Plant derived polyprenoids include…?

A

the Fat soluble Vitamin A,D,E &K and beta carotene (pro.A)

49
Q

Peroxidation is?

A

Auto oxidation.

50
Q

What are reactive oxygen species (ROS)?

A

free radicals containing oxygens.

51
Q

When are ROS’s produced?

A

During peroxide formation of fatty acids containing methylene-interrupted double bonds.

52
Q

What is Lipid peroxidation?

A

It’s a chain reaction providing continuos supply of ROS, that initiate further peroxidation, thus have potentially bad effect.
–> done in 3 steps: Initiation, propagation and termination.

53
Q

Which are the two classes of antioxidants?

A

1) Preventive antioxidants: they reduce the rate of chain elongation.
2) Chain breaking Antioxidants: they interfere with chain propagation.

54
Q

Name the chain breaking antioxidants.

A

catalase, glutatione peroxidase…… etc.

55
Q

How are liposomes formed?

A

by sonicating an amphipathic lipid in aqueous medium.

56
Q

mixed micells are?

A

Bile salts in micells and liposomes, they’re important for bsorbance of lipids from the intestine.

Biochem K (10 decks)

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