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BIOCHEMISTRY > ME04 - Metabolism of Acylglycerols and Sphingolipids > Flashcards

ME04 - Metabolism of Acylglycerols and Sphingolipids Flashcards

1
Q

Major storage lipid in the adipose tissue

A

TRIACYLGLYCEROL

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2
Q

Major components of plasma and other membranes

A

PHOSPHOLIPIDS AND GLYCOSPHINGOLIPIDS

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3
Q

Lipid with a component of lung surfactant

A

Dipalmitoyl lecithin

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4
Q

Lipid which is a precursor of hormone second messenger

A

Inositol phospholipid

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5
Q

Lipid that is involved in inflammation and chemotaxis

A

Platelet activating factor

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6
Q

Lipid that is important in intercellular communication and contact, as receptors for bacterial toxins and as ABO blood group substance

A

Glycosphingolipid

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7
Q

CATABOLISM OF TAGs

A

Triacylglycerol&raquo_space; (___Lipase)&raquo_space;

Free fatty acids (Goes to the plasma bound to albumin > Tissue uptake > B-oxidation or reesterification ) + Glycerol (&raquo_space; Glycerol kinase > Glycerol 3-phosphate > Reesterification )

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8
Q

Processes involved in the BIOSYNTHESIS
of TRIACYLGLYCEROL and PHOSPHOLIPIDS

A

ACTIVATION OF GLYCEROL

In the absence of glycerol kinase, glycerol 3-phosphate is derived from dihydroxyacetone phosphate (DHAP)

Dihydroxyacetone phosphate&raquo_space; (Enzyme: Glycerol 3-phosphate Dehydrogenase)&raquo_space; Glycerol 3- phosphate

Other products: NADH + H+ ; NAD+

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9
Q

ACTIVATION OF FATTY ACIDS

A

_ Involves hydrolysis of two high-energy bonds _ ENZYME: Acyl CoA Synthetase

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10
Q

SYNTHESIS OF TAG

A

DHAP > G3Phosphate > Monoacylglycerol 3Phosphate > Phosphatidic Acid > 1,2-Diacylglycerol > Triacylglycerol

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11
Q

What is the ALTERNATIVE PATHWAY OF TRIACYLGLYCEROL SYNTHESIS IN THE INTESTINAL MUCOSA

A

2-Monoacylglycerol&raquo_space; 1,2-Diacylglycerol&raquo_space; Triacylglycerol

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12
Q

Example of Phospholipids

A

Phosphatidylethanolamine
Phosphatidylserine
Phosphatidylcholine________

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13
Q

How does Phosphatidylethanolamine form Phosphatidylcholine

A

Phosphatidylethanolamine can undergo progressive methylation with SAM as methyl donor to form phosphatidylcholine

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14
Q

Synthesis of Cardiolipin

A

Phosphotidic acid&raquo_space; CDP-Diacylglycerol > +Phosphatidylglycerol = Cardiolipin

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15
Q

WHAT IS THE ROLE OF PHOSPHATIDYLINOSITOL 4,5- BISPHOSPHATE IN HORMONE ACTION

A

Activator of protein kinase C

Effective releaser of Ca++ from intracellular storage

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16
Q

Major component of lung surfactant

A

DIPALMITOYL PHOSPHATIDYLCHOLINE

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17
Q

FUNCTION/EFFECT OF LUNG SURFACTANT

A

Lung surfactant reduces the surface tension of water (fluid) lining the surface of the alveolar sac, preventing collapse.

Without lung surfactant, sac collapses.
Ten times the normal pressure is needed for re-inflation.

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18
Q

Example of ETHER PHOSPHOLIPIDS

A

Plasmalogen and PAF

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19
Q

Phospholipid in the mitochondria

A

Plasmalogen

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20
Q

Function of PAF (Plasma-Activating Factor)

A

Aggregates platelets
Hypotensive
Ulcerogenic
Involved in inflammation, chemotaxis and protein phosphorylation

21
Q

Where does the SYNTHESIS OF PLASMALOGEN AND PAF occur?

A

Occur in the peroxisomes

22
Q

The common intermediate in the synthesis of triacylglycerol and glycerophospholipids

A

PHOSPHATIDATE

23
Q

HOW ARE TRIACYLGLYCEROL AND PHOSPHOLIPID SYNTHESIS REGULATED?

A

Driven by availability of free fatty acids
Fatty acids that escapes oxidation are preferentially converted to phospholipids, and when this requirement is satisfied they are used for triacylglycerol synthesis

24
Q

IN THE CATABOLISM OF PHOSPHOLIPIDS,
Different portions of the molecule turnover at different rates. True or False?

A

TRUE

25
Q

Order of Phospholipases action sites

A

PLP A1, PLP A2, PLP C, PLP D

26
Q

Catalyze transfer of a fatty acid residue from position 2 of lecithin to cholesterol to from cholesteryl ester
Responsible for cholesteryl esters in plasma lipoproteins

A

LECITHIN:CHOLESTEROL ACYLTRANSFERASE (LCAT)

Lecithin + CHOL&raquo_space; (LCAT)&raquo_space; Lysolecithin + Cholesteryl ester

27
Q

Parent compound of all sphingolipids

A

Ceramide

28
Q

Function of Ceramide

A

An important signaling molecule regulating pathways including programmed cell death (apoptosis), the cell cycle, and cell differentiation and senescence

29
Q

Where is Ceramide synthesized?

A

In the endoplasmic reticulum from serine and palmitoyl CoA

30
Q

Backbone of Ceramide are

A

Serine, Palmitoyl CoA and Fatty Acid

31
Q

Present in plasma membranes; especially prominent in myelin, a membranous sheath that surrounds and insulates the axons of some neurons

A

SPHINGOMYELIN

32
Q

How do you form Sphingomyelin from Ceramide?

A

Ceramide&raquo_space; (Phosphatidylcholine>Diacylglycerol)&raquo_space; Sphingomyelin

33
Q

Include cerebrosides and gangliosides
Constituents of outer leaflet of the plasma membrane

A

Glycosphingolipid

34
Q

C24 fatty acids that make up Glycosphingolipids

A

lignoceric acid cerebronic acid nervonic acid

35
Q

Function of Glycosphingolipids

A

Important in intracellular communication and contact, as antigens such as ABO blood groups and as receptors for bacterial toxins

36
Q

SYNTHESIS OF CEREBROSIDES AND THEIR SULFO DERIVATIVES

A

Ceramide&raquo_space; (UDP-Gal > UDP)&raquo_space; Galactosylceramide
(Cerebroside)&raquo_space; (PAPS)&raquo_space; Sulfogalactosylceramide
(Sulfatide)

37
Q

CATABOLISM OF SPHINGOLIPIDS

A

Degraded within the lysosomes of phagocytic cells, particularly the histiocytes or macrophages of the RE system in the liver, spleen and bone marrows
Involves stepwise removal of each sugar and other components catalyzed by enzymes (specifically hydrolases) that cleaves specific bonds

38
Q

Demyelinating disease
Involves the loss of both phospholipids and sphingolipids from white matter
Leads to slowing and eventual cessation of nerve impulse transmission

A

MULTIPLE SCLEROSIS
Manifest as weakness, lack of coordination, speech and vision problems

39
Q

Due to absence of enzymes that degrade glycosphingolipids in the lysosomes
Rate of synthesis of stored lipids is normal
Complex lipids containing ceramide accumulate in cells, particularly neurons, causing neurodegeneration and shortening of life span

A

SPHINGOLIPID STORAGE DISEASES

40
Q

Deficiency in Hexosaminidase A
Accumulating GM2 ganglioside
Rapidly progressing mental retardation, blindness, early mortality

A

Tay-Sachs Disease

41
Q

Deficiency in Hexosaminidase B
Accumulating Globoside, GM2 ganglioside
Same symptoms as Tay-Sachs, progresses more rapidly

A

Sandhoff-Jatzkewitz disease

42
Q

Deficiency in GM2 activator (GM2A)
GM2 ganglioside

A

Tay-Sachs AB variant

43
Q

Deficiency in Glucocerebrosidase
Accumulating Glucocerebroside
Hepatosplenomegaly, mental retardation in nfantile form, long bone degeneration

A

Gaucher disease

44
Q

Deficiency in a-Galactosidase A
Accumulating Globotriaosylceramide also called ceramide
trihexoside (CTH)
Kidney failure, skin rashes

A

Fabry disease

45
Q

Deficiency in Sphingomyelinase

A

Niemann-Pick Disease

46
Q

Deficiency in Galactocerebrosidase
Accumulating Galactocerebroside
Mental retardation, myelin deficiency

A

Krabbe disease; globoid leukodystrophy

47
Q

Deficiency in Arylsulfatase A
Sulfatide
Mental retardation, metachromasia of nerves

A

Sulfatide lipodosis; metachromatic leukodystrophy

48
Q

Deficiency in a-L-Fucosidase
Accumulating Pentahexosylfucoglycolipid
Cerebral degeneration, thickened skin, muscle spasticity

A

Fucosidosis

49
Q

Deficiency in Acid ceramidase
Accumulating Ceramide
Hepatosplenomegaly, painful swollen joints

A

Farber lipogranulomatosis

BIOCHEMISTRY (25 decks)

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