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B2 Biochem > Metabolism Of Complex Lipids > Flashcards

Metabolism Of Complex Lipids Flashcards

1
Q

definition of Lipids

A

Diverse and ubiquitous group of organic compounds that are insoluble in water but soluble in organic solvents

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2
Q

Lipids are soluble in ______ but insoluble in ________

A

Organic Solvents, water

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3
Q

Examples of lipids

A

FAs, TAG, phospholipids, sterols, sphingolipids, terpenes

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4
Q

Classification of Lipids

A

GLYCEROL based and NONGLYCEROL based.

If glycerol based, then they are SIMPLE or COMPOUND

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5
Q

What are fats and oils classified as?

A

Simple glycerol based lipids

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6
Q

What are phospholipids and glycolipids classified as?

A

Complex glycerol based lipids

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7
Q

What are sphingolipids, glycophingolipids, steroids and waxes classified as?

A

Complex lipids. Or complex non-glycerol based lipids.

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8
Q

Structure of Phospholipids

A

Hydrophilic head, hydrophobic tail

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9
Q

hydrophilic head of phospholipids are composed of:

A

Phosphate group and glycerol backbone

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10
Q

Hydrophobic tails of phospholipids are composed of:

A

FA hydrocarbon tail

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11
Q

What’s the special characteristic of phospholipids? How are they arranged in water?

A

They’re amphipathic molecules.

Heads are out, tails are in, to form the lipid bilayer

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12
Q

Functions of Phospholipids

A

Structural component, reservoir for intercellular second messengers, anchor point for membrane proteins

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13
Q

Phospholipids function as a component of:

A

Lipoprotein, pulmonary surfactants, bile

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14
Q

precursor for the synthesis of all other glycerophospolipids and TAG

A

phosphatidic acid (PA)

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15
Q

phosphatidic acids’ relevance to membrane structure

A

Influences membrane curvature and vesicles formation

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16
Q

The most abundant phospholipid

A

Phosphatidylcholine (PC, lecithin)

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17
Q

PC

A

Phosphatidylcholine

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18
Q

PA

A

Phosphatidic acid

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19
Q

PC composition

A

PA + choline

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20
Q

PC is a major component of

A

Lung surfactant

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21
Q

Lung surfactant is a mixture of:

A

90% lipids and 10% proteins

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22
Q

Roles of Lung Surfactant

A

Decrease surface tension, reduce pressure for re-inflation of alveoli, and prevent alveolar collapse

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23
Q

What is atelactasis?

A

Alveolar collapse

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24
Q

Respiratory Distress Syndrome is due to:

A

Insufficient lung surfactant

Significant cause of neonatal deaths in Western Countries

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25
Q

Phosphatidylethanolamine

A

PA + ethanolamine

2nd most abundant phospholipid

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26
Q

PE

A

Phosphatidylethanolamine

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27
Q

Phosphatidylserine

A

PS

PA + serine

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28
Q

PS

A

Phophatidylserine

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29
Q

PS is only found where?

A

Inner leaflet of plasma membrane

Required for membrane synthesis and plays a role in recognition of apoptotic cells

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30
Q

Phosphatidylinositols

A

PI

PA+inositol

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31
Q

PI

A

Phosphatidylinositol

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32
Q

Why is PI an unusual lipid?

A

It contains a stearic acid at C1 and a arachidonic acid at C2

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33
Q

Functions of PIs

A

Reservoir of arachidonic acid

Precursor for prostaglandins

OH groups can be phosphorylated (producing PIP2, precursor for IP3 and DAG)

Serve as anchor points for proteins

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34
Q

PI is a precursor for:

A

IP3 and DAG, after it becomes phoporylated to PIP2

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35
Q

Phosphatidylglycerol

A

PG

PA + glycerol

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36
Q

PG

A

Phosphatidylglycerol

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37
Q

PG is a precursor for:

A

Surfactant

And for synthesis of cardiolipin

38
Q

2 PA molecules, exclusive to the innermitochondrial membrane, maintains the structure and function of ETC complexes

A

Cardiolipin

39
Q

FA at c-1 is attached via ether-linkage (not ester)

A

Ether glycerophospholipids

40
Q

2 types of ether glycerophospholipids, which are based on what?

A

Based on the FA at c-1 linkage,

  1. Plasmalogens (unsaturated FA arc-1)
  2. Platelet-activating factor (PAF)(saturated FA at c-1)
41
Q

Type of ether glycerophospholipid with unsaturated FA at c-1

A

Plasmalogens

42
Q

What type of Plasmalogens are in the heart muscle? Nerve tissue?

A

PhosphatidALcholine, heart

PhosphatidALethanolamine, nerve

43
Q

What is the PAF?

A

Type of ether glycerophospholipid with a saturated FA at c-1 and a short acetyl group at c-2 (instead of an acyl

44
Q

What is one of the most potent bio active molecules (triggers thrombotic and inflammatory events)?

A

PAF

Platelet-activating factor

45
Q

What is PA synthesized from?

A

Glycerol-3-P or 2 fatty acyl CoA

46
Q

once PA is produced, it can go through what 2 pathways?

A

CDP-DAG pathway to produce PI, PG, or Cardiolipin

DAG to produce PC or PE

47
Q

Ether lipids are produced in what molecules?

A

Peroxisomes

48
Q

CDP-DAG pathways is used for:

A

PI, PG and Cardiolipin

49
Q

Transfer of activated CDP-choline or CDP-ethanolamine to DAG is used for:

A

PC, PE synthesis

50
Q

PS is synthesized from:

A

PE is the substrate

Base-exchange reaction

Reversible step

51
Q

PS is decarboxylated to form:

A

PE

52
Q

PC is produced where?

A

In the liver

53
Q

PC is secreted from liver cells in:

A

The bile

54
Q

PC are incorporated into:

A

Lipoproteins and are secreted

55
Q

Pathway for production of PC

A

PS -> PE -> PC

PS loses its’ carboxyl group, then PE adds 3 methyl groups to become PC

56
Q

Functions of Phospholipases (PLPs)

A

Hydrolysis the phospho digester bonds of glycerophospholipids

Site specific cleavage (each PLP acts on a specific bond)

Release bioactive molecules that can serve as second messengers (DAG, IP3)

Participate in remodeling of phospholipids

57
Q

Structure of sphingolipids

A

Sphingomyelin + ceramide

58
Q

What is a ceramide?

A

FA + sphingosine

59
Q

What is SM?

A

Sphingomyelin, ceramide + phosphocholine

Predominant sphingophospholipid in mammalian cells

Major structural sphingolipid in the plasma membrane

Abundant in nerve tissue

60
Q

What sphingolipid is a major structural sphingolipid in the plasma membrane and is abundant in nerve tissue?

A

Sphingomyelin (SM)

61
Q

What is the main precursor for SM and all glycophingolipids?

A

Ceramide

62
Q

What do ceramides do in the skin?

A

Maintain the skins’ water-permeability barrier

Decreased levels of ceramides are associated with skin diseases

63
Q

What is a sphingosine composed of?

A

Palmitic acid + serine

64
Q

Functions of GSLs in Human cells

A

Regulation of cellular interactions

regulation of growth and development

Antigenic (source of blood group antigens) in embryonic development, tumors, and toxins/viruses

65
Q

What is a neutral GSL?

A

Cerebroside

66
Q

What is a Cerebroside made of?

A

Ceramide and a sugar

Ex: galactosylceramide

67
Q

What do cerebrosides do?

A

Found in membranes

Lipid rafts formation

Predominant in nerve tissue

68
Q

What GSLs are negatively charged at pH of 7?

A

Acidic GSLs

69
Q

What is a ganglioside?

A

Type of acidic GSL

Ceramide + oligosaccharide + NANA

70
Q

What is a NANA?

A

N-acetylneuramic acid

71
Q

Where are gangliosides found?

A

Ganglion cells in the CNS

High amounts of these lipids are from lipid storage disorders

72
Q

What is a sulfatide?

A

A type of Acidic GSL

Galactocerebroside + sulfate group

Found in brain and kidney

73
Q

Sphingolipid synthesis

A

Begins in ER with condensation of palmitoyl CoA and L-serine

Forms sphingoid backbone and produces ceramide via several steps

Ceramide is transferred to Golgi, where is is used a substrate to synthesize Sphingomyelin and GSLs

SM and GSLs are then transported/secreted into lipoproteins

74
Q

Local (limited) degradation of SM

A

In plasma membrane to produce ceramides for cell signaling

75
Q

Complete Degradation of SM and GSLs

A

Occurs in lysosomes by different acidic enzymes at pH 4.5

76
Q

Sphingolipid synthesis and degradation are:

A

Balanced tightly at constant levels

77
Q

Deficiency in an enzyme in the lysosomes results in:

A

Sphingolipidose, common name for a lysosomal lipid storage disease

78
Q

Sphingolipidoses

A

If particular acid hydrolase is defective, SL substrate accumulates.

Nervous tissues are affected because of high abundance of SLs.

Autosomal Recessive

May be fatal.

Genetic variability.

Incidence is low in most populations.

More frequent in Ashkenazi Jewish population

79
Q

Tay-Sachs disease (enzyme deficiency, Lipid accumulation, clinical symptoms)

A

Hexosaminidase A

Gm2 Ganglioside

Mental retardation, blindness, muscular weakness

80
Q

Fabry’s Disease (enzyme deficiency, Lipid accumulation, clinical symptoms)

A

alpha-Galactosidase

Globotriasylceramide

Skin rash, kidney failure (x-linked)

81
Q

Metachromic leukodystrophy (enzyme deficiency, Lipid accumulation, clinical symptoms)

A

Arylsulfatase A

3-sulfogalactosylceramide

Mental retardation, demyelination

82
Q

Krabbe’s disease (enzyme deficiency, Lipid accumulation, clinical symptoms)

A

Beta-galactosidase

Galactosylceramide

Mental retardation, myelin almost absent

83
Q

Gaucher’s disease (enzyme deficiency, Lipid accumulation, clinical symptoms)

A

Beta-glucosidase

Glucosylceramide

Enlarged liver and spleen, erosion of long bones, mental retardation in infants

84
Q

Niemann-Pick disease (enzyme deficiency, Lipid accumulation, clinical symptoms)

A

Sphingomelinase

Sphingomyelin

Enlarged liver and spleen, mental retardation, fatal in early life

85
Q

Farber’s disease (enzyme deficiency, Lipid accumulation, clinical symptoms)

A

Ceramidase

Ceramide

Hoarseness, dermatitis, skeletal deformation, mental retardation, fatal in early life

86
Q

What is the most common form of Gm2 gangliosidosis?

A

TaySachs disease

87
Q

Sandy off disease is similar to:

A

TaySachs disease

88
Q

Which Sphingolipidoses are related to Cherry Red macula?

A

TaySachs disease

Sandhoff disease

Niemann-Pick disease

89
Q

Neman-Pick disease is the accumulation of:

A

Sphingomyelin

Causing enlarged spleen and liver (hepatosplenomegaly)

Cherry-red macula

90
Q

Cherry-red spot in macula may indicate

A

Cherry Red Macula

Taysachs, sandhoff or Niemann-pick

Accumulation of Sphingomyelin (Enlarged spleen/liver)

Accumulation of gangliosides (blindness)

B2 Biochem (13 decks)

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