ME04 - Metabolism of Acylglycerols and Sphingolipids

Question 1

Major storage lipid in the adipose tissue

Answer 1

TRIACYLGLYCEROL

Question 2

Major components of plasma and other membranes

Answer 2

PHOSPHOLIPIDS AND GLYCOSPHINGOLIPIDS

Question 3

Lipid with a component of lung surfactant

Answer 3

Dipalmitoyl lecithin

Question 4

Lipid which is a precursor of hormone second messenger

Answer 4

Inositol phospholipid

Question 5

Lipid that is involved in inflammation and chemotaxis

Answer 5

Platelet activating factor

Question 6

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

Answer 6

Glycosphingolipid

Question 7

CATABOLISM OF TAGs

Answer 7

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 )

Question 8

Processes involved in the BIOSYNTHESIS
of TRIACYLGLYCEROL and PHOSPHOLIPIDS

Answer 8

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+

Question 9

ACTIVATION OF FATTY ACIDS

Answer 9

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

Question 10

SYNTHESIS OF TAG

Answer 10

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

Question 11

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

Answer 11

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

Question 12

Example of Phospholipids

Answer 12

Phosphatidylethanolamine
Phosphatidylserine
Phosphatidylcholine________

Question 13

How does Phosphatidylethanolamine form Phosphatidylcholine

Answer 13

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

Question 14

Synthesis of Cardiolipin

Answer 14

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

Question 15

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

Answer 15

Activator of protein kinase C

Effective releaser of Ca++ from intracellular storage

Question 16

Major component of lung surfactant

Answer 16

DIPALMITOYL PHOSPHATIDYLCHOLINE

Question 17

FUNCTION/EFFECT OF LUNG SURFACTANT

Answer 17

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.

Question 18

Example of ETHER PHOSPHOLIPIDS

Answer 18

Plasmalogen and PAF

Question 19

Phospholipid in the mitochondria

Answer 19

Plasmalogen

Question 20

Function of PAF (Plasma-Activating Factor)

Answer 20

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

Question 21

Where does the SYNTHESIS OF PLASMALOGEN AND PAF occur?

Answer 21

Occur in the peroxisomes

Question 22

The common intermediate in the synthesis of triacylglycerol and glycerophospholipids

Answer 22

PHOSPHATIDATE

Question 23

HOW ARE TRIACYLGLYCEROL AND PHOSPHOLIPID SYNTHESIS REGULATED?

Answer 23

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

Question 24

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

Answer 24

TRUE

Question 25

Order of Phospholipases action sites

Answer 25

PLP A1, PLP A2, PLP C, PLP D

Question 26

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

Answer 26

LECITHIN:CHOLESTEROL ACYLTRANSFERASE (LCAT) Lecithin + CHOL >> (LCAT) >> Lysolecithin + Cholesteryl ester

Question 27

Parent compound of all sphingolipids

Answer 27

Ceramide

Question 28

Function of Ceramide

Answer 28

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

Question 29

Where is Ceramide synthesized?

Answer 29

In the endoplasmic reticulum from serine and palmitoyl CoA

Question 30

Backbone of Ceramide are

Answer 30

Serine, Palmitoyl CoA and Fatty Acid

Question 31

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

Answer 31

SPHINGOMYELIN

Question 32

How do you form Sphingomyelin from Ceramide?

Answer 32

Ceramide >> (Phosphatidylcholine>Diacylglycerol) >> Sphingomyelin

Question 33

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

Answer 33

Glycosphingolipid

Question 34

C24 fatty acids that make up Glycosphingolipids

Answer 34

lignoceric acid cerebronic acid nervonic acid

Question 35

Function of Glycosphingolipids

Answer 35

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

Question 36

SYNTHESIS OF CEREBROSIDES AND THEIR SULFO DERIVATIVES

Answer 36

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

Question 37

CATABOLISM OF SPHINGOLIPIDS

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

SPHINGOLIPID STORAGE DISEASES

Question 40

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

Answer 40

Tay-Sachs Disease

Question 41

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

Answer 41

Sandhoff-Jatzkewitz disease

Question 42

Deficiency in GM2 activator (GM2A) GM2 ganglioside

Answer 42

Tay-Sachs AB variant

Question 43

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

Answer 43

Gaucher disease

Question 44

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

Answer 44

Fabry disease

Question 45

Deficiency in Sphingomyelinase

Answer 45

Niemann-Pick Disease

Question 46

Deficiency in Galactocerebrosidase Accumulating Galactocerebroside Mental retardation, myelin deficiency

Answer 46

Krabbe disease; globoid leukodystrophy

Question 47

Deficiency in Arylsulfatase A Sulfatide Mental retardation, metachromasia of nerves

Answer 47

Sulfatide lipodosis; metachromatic leukodystrophy

Question 48

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

Answer 48

Fucosidosis

Question 49

Deficiency in Acid ceramidase Accumulating Ceramide Hepatosplenomegaly, painful swollen joints

Answer 49

Farber lipogranulomatosis