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Week 11-SHANE > Complex Lipids II > Flashcards

Complex Lipids II Flashcards

1
Q

What are the categories of glycerolipids?

A

1) triacylglycerols
2) glycerophopsholipids
3) ether glycerolipids

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2
Q

What complex lipid is a major component of a plasma membrane?

A

phospholipids (sphingolipids are also components of the plasma membrane)

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3
Q

What is the difference in structure between a glycerophospholipid and an ether glycerolipid?

A

glyercophosplolipids have a glycerol backbone with two attached fatty acids at positions 1 and 2 connected by ester bonds and an activated head group attached to the glycerol backbone by a phosphate

ether glycerolipids have an ether bond (instead of an ester bond) on the 1 position with a long chain ‘alcohol- (the alcohol is the same as the long chain hydrocarbon that makes the fatty acyl but without the C=O bond) attached to the glycerol backbone, a single fatty acid in the 2 position, and an activated head group attached to the glycerol backbone by a phosphate

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4
Q

What are the categories of sphingolipids?

A

sphingophospholipids and glycolipids

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5
Q

What is a structure similarity between glycerolipids, phospholipids, and sphingolipids?

A

they all have at least one fatty acid and almost all (except triacylglycerol) have an activated head group)

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6
Q

What kinds of glycerophospholipids are primarily found on the cytosolic side of the plasma membrane?

A

phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylinositol bisphosphate (PI)

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7
Q

What kinds of complex lipids are primarily found on the extracellular part of the plasma membrane?

A

sphingomyelin, phosphatidylcholine, and glycolipids

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8
Q

What are the types of ether glycerolipids?

A

plasmalogens and platelet activating factor (PAF)

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9
Q

Where are plasmalogens commonly found?

A

mitochondria lipids, myelin, and muscle

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10
Q

What is platelet activating factor?

A

signaling molecule released from phagocytic blood cells in response to stimuli; causes platelet aggregation, edema, and hypotension

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11
Q

How is the ethanolamine plasmalogen “phosphotidylethanolamine” synthesized?

A

start with DHAP, which reacts with an activated fatty acyl CoA to give an ester group on the 1 carbon. Another fatty acyl CoA becomes reduced by 2 NADPH to a fatty acyl alcohol. Reaction of the fatty acyl alcohol and the product of the interaction between DHAP and the activated fatty acyl CoA displaces the ester bond on the 1 position, forming an ether bond. The 2 carbon is reduced to form an alcohol for the addition of a fatty acid and the 3 carbon is dephosphorylated. An activated CDP-ethanolamine head group reacts with the 3 carbon to form the head. Further oxidation modifies the 1 carbon to its final, unsaturated (1-alkenyl double bond) form

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12
Q

What are the main structural differences between phosphotidylethanolamine (plasmalogen) and PAF?

A

phosphotidylethanolamine - the 2 carbon has an acyl group and the 1 carbon ether chain is unsaturated

PAF- the 2 carbon has an acteyl group, the 1 carbon ether chain is saturated, and the head group is choline

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13
Q

What are the major categories of sphingolipids?

A

sphingophospholipids and glycolipids

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14
Q

What are the subsets of sphingophospholipids?

A

sphingomyelin- a major component of cell membranes

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15
Q

What are the subsets of glycolipids?

A

Cerebrosides
Sulfatides
Globosides
Gangliosides

(name depends on the sugar/carbohydrate moiety stuck on the 3 carbon of the sphingosine backbone)

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16
Q

What is the backbone of the sphingolipids made of?

A

a sphingosine molecule

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17
Q

A sphingosine joined together with a fatty acid by an amide bond is called what?

A

a ceramide

18
Q

What do sphingolipids primarily do?

A

they are in the outer part of the plasma membrane and are involved in the cell-cell (e.g. ABO blood type), and cell-matrix interactions.

Sphingomyelin is enriched in CNS and in the myelin sheath

19
Q

What families of complex lipids have a sphingosine backbone?

A

sphingophospholipids and glycolipids (aka the sphingolipids)

20
Q

What is the difference between the structure of glycolipids and sphingophospholipids?

A

both have sphingosine backbones- makes an L shape- (where the 2 carbon fatty acid is attached to the sphingosine backbone by an amide bond, not an ester bond) but glycolipids have a phosphorylated choline on the 3 carbon and sphingophospholipids have a carbohydrate on the 3 carbon

21
Q

How is the ceramide backbone of sphingophospholipids and glycolipids made?

A

1) start with palmitoyl CoA (16C fatty acyl CoA)
2) palmitoyl CoA reacts with serine in a enzymatic reaction that requires paradoxyl-phosphate (PLP) (and releases Co2 and CoA) forming a sphingosine
3) sphingosine is reduced to dihydrospingosine by NADPH
4) dihydrospingosine has a fatty acyl CoA added to a nitrogen on the serine residue
5) oxdiation by FAD (goes to FAD(2H)) adds a double bond on the backbone

22
Q

glycolipids and sphingophospholipids are especially enriched where?

A

in neural tissue

23
Q

What is mucolipidosis?

A

an inability to degrade sphingolipids and glycolipids (have CNS related symptoms)

ex. Tay-Each’s disease, Gaucher’s disease

24
Q

To make sphingomyelin (subset of sphingophospholipids) from a ceramide backbone, what is needed? Where is sphingomyelin found?

A

a phosphotiydylcholine (PC) molecule to donate its activated choline residue to the 3 carbon

enriched in myelin sheath

25
Q

Where are glycolipids especially abundant?

A

neural tissue

26
Q

What do glycolipids primarily do?

A

cell-cell recognition, protect cells, and form the binding sites for some toxins (like choleratoxin)

27
Q

T or F. glycolipids are ceramide derivatives

A

T. But they contain sugars, not activated choline and phosphate like in sphingophospholipids

28
Q

What are cerebrosides composed of on the 3 carbon?

A

a single sugar attachment to the the ceramide backbone (e.g. ceramide bound to glucose makes glucocerebroside)

29
Q

What are globosides composed of on the 3 carbon?

A

multiple sugar attachements on the ceramide backbone.

30
Q

What are the neural glycolipid categories?

A

cerebrosides and globosides

31
Q

What are the acidic glycolipid categories?

A

sulfatides and gangliosides (negatively charged at phsyiological pH)

contain an N- acetylneuraminic acid (NANA) (gangliosides) or sulfate (sulfatides) attached to the sugar moiety of a neutral glycolipid

32
Q

Where does synthesis of glycolipids occur?

A

in the ER and in golgi

33
Q

The sulfate for sulfatides is donated by what?

A

phosphoadenosine phosphosulfate (PAPS)

34
Q

How is galactocerebroside formed?

A

addition of an activated galactose (aka UDP-galactose) to the ceramide backbone

35
Q

How is sulfatide formed?

A

addition of a sulfate group from PAPS to galactocerebroside

36
Q

How is glucocerebroside formed?

A

addition of an activated glucose (aka UDP-glcuose) to the ceramide backbone

37
Q

How is globoside formed?

A

addition of a galactose group to a glucocerebroside by an appropriate enzyme

38
Q

How is ganglioside formed?

A

addition of UDP-activated sugars to glucocerebroside, followed by addition of CMP- NANA (makes GM3).

39
Q

What are sphingolipids (sphingphospholipids and glycolipids) degraded by?

A

lysosomal enzymes

40
Q

What is Gaucher Disease?

A

B-glucocerebroside deficiency causing accummulation

autosomal-recessive

41
Q

What is Tay-Sach Disease?

A

hexoaminidaside A deficiency/absent causing GM2 ganglionoside accummulation

autosomal recessive

CNS problems, seizures, muscle weakness,

42
Q

What is Fabry Disease?

A

deficiency of a-galactosidase A causing accumulation of globosides

autsomal recessive

Week 11-SHANE (18 decks)

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