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Biological Chemistry > Lipids 2 > Flashcards

Lipids 2 Flashcards

(70 cards)

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1
Q

What is Glycerolphospholipids composed of ?

A

Alcohol, Phosphate, Glycerol and 2 Fatty acids

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2
Q

Fatty acids form ester linkages with the first and second hydroxyl groups of ?

A

L-glycerol-3-phosphate

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3
Q

The phosphate group is ?

A

Charged at physiological pH

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4
Q

Where does biosynthesis of membrane phospholipids occur ?

A

In cytosol

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5
Q

Phospholipid head is attached to ? and by what ?

A

Phospholipid head is attached to diacylglycerol by a phosphodiester bond

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6
Q

PLA2 can release ?

A

Inflammatory mediators such as histamine, prostaglandins & leukotrienes

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7
Q

What happens in absence of strict regulation of PLA2 ?

A

A disproportionate release of inflammatory mediators can take place

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8
Q

What does Glucocorticoids upregulate ?

A

Lipocortin which inhibits PLA2 and reduce the inflammatory response

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9
Q

What is Lecithin ?

A

They are mixtures of glycerol phospholipids that contain the amino alcohol choline e.g. phosphatidylcholine

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10
Q

Where is Lecithin found ?

A

Found in egg yolks, wheat germ & soybeans

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11
Q

Lecithin is extracted and used as emulsifying agent in food because ? and what does this enable ?

A

Extracted & used as emulsifying agent in food because it has both polar & non-polar properties. This enables it to mix other fats & oils with water

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12
Q

What does Cephalin contain?

A

The amino alcohols serine or ethanolamine

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13
Q

Where are cephalins found?

A

Found in most cell membranes, particularly brain tissue (e.g. Phosphatidyl ethanolamine)

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14
Q

Cephalin is important in ?

A

The blood coagulation process, found in blood platelets (e.g. Phosphatidyl ethanolamine & Phosphatidyl serine work to increase thrombin)

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15
Q

Difference between Lecithin and Cephalin ?

A

Lecithin contains the amino alcohol - choline. Whereas, Cephalins contain the amino alcohol – ethanolamine (or serine)

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16
Q

Sphingolipids have a backbone of ?

A

Sphingosine (a derivative of ceramide)

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17
Q

Sphingosine is a ?

A

18-C amino alcohol with unsaturated hydrocarbon tail

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18
Q

What Sphingolipids contain?

A

Choline, Phosphate, Sphingosine (with built in hydrocarbon tail) and Fatty acid

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19
Q

Polar head group is connected to ?

A

Sphingosine by a glycosidic or phosphodiester linkage.

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20
Q

Where are Sphingolipids found ?

A

Found largely in the outer face of plasma membranes

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21
Q

Biological relevance of Sphingolipids ?

A
  • 60+ human sphingolipids identified in cell membranes
  • Prominent in neurons & cell recognition sites
  • Define human blood groups
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22
Q

Ceramide is the precursors to ?

A

Sphingolipids

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23
Q

What is Ceramide formed by?

A

Fatty acid attached to carbon 2 via an amide bond

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24
Q

What are Sphinglipidoses ?

A

They are disorders of sphingolipid metabolism Eg. Nieman-Picks disease

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25
Ceramide + Water =
Fatty acid + Sphingosine
26
What are Sphingolipids subdivided into ?
Sphingomyelins, Glycosphingolipids (neutral glycolipids) and Gangliosides
27
Phosphatidylcholine (a glycerophospholipid) and sphingomyelin (a sphingolipid) have similar ?
3D structure & physical properties
28
What different roles to they plan in membranes ?
Sphingomyelin is abundant in myelin sheath that surrounds some nerve cells in animals
29
What is Glycosphingolipids subdivided into ?
Glycosphingolipids (Glycolipids) One or more sugars connected directly to the ceramide - Cerebrosides – 1 sugar - Globosides – 2+ sugars Gangliosides Complex sphingolipids with oligosaccharide polar head & 1> sialic acid termini (-ve charge at pH7).
30
Galactose + ceramide =
Galactocerebroside
31
What does Cerebroside contain ?
Monosaccharides, Sphingosine (with attached hydrocarbon tail) and fatty acid
32
What does Ganglioside contain ?
NANA (Sialic acid), Sugar(s), Sphingosine (with attached hydrocarbon tail) and fatty acid
33
Where is the highest sialic acid concentration ? and why important role does it play ?
The brain has highest sialic acid concentration where it plays an important role in neural transmission & ganglioside structure
34
What can Glycosphingolipids determine and using what part?
Blood groups (O, A, B) determined in part by oligosaccharide head group of glycosphingolipids
35
Simply explain Fat (Triacylglycerols - TAGs) ?
Simplest storage lipids (energy source) constructed from fatty acids & alcohol
36
What are lipids divided into?
Lipids that contain fatty acids (complex lipids) - storage lipids: Triacylglycerols - membrane lipids: Phospholipids & Glycolipids Lipids that do not contain fatty acids e.g. cholesterol, vitamins, pigments.
37
What is the advantage of fats over polysaccharides ?
- Fatty acids carry more energy per carbon because they are more reduced. - Fatty acids carry less water per gram because they are nonpolar. - Glucose & glycogen are for short-term energy needs & quick delivery - Fats are for long-term (months) energy needs, good storage and slow delivery.
38
Explain the structure of TAGs?
- A triglyceride (TG, triacylglycerol – TAG or triacylglyceride) is an ester derived from glycerol & 3-4 Fatty Acids - All 3 hydroxyl groups of glycerol are esterified - Many different types: mainly division between saturated & unsaturated - The primary storage form of lipids (body fat) - Less soluble in water than FA due to esterification of carboxylate group - Less dense than water: fats & oils float
39
High levels of triglycerides in the bloodstream have been linked to ?
Atherosclerosis and the risk of heart disease & stroke
40
Properties of TAGs ?
- Neutral (no ionic groups) - Non-polar & hydrophobic - Insoluble in water - Transported around the body shielded from water in plasma - Carried by large lipid particles the lipoproteins - Simple TAGs have 3 identical fatty acids esterified to glycerol backbone - Mixed TAGS have 2-3 differing fatty acids
41
Basic structure of lipoprotein?
Non-polar lipid core containing TAG & cholesterol esters (cholesterol linked to fatty acid)
42
5 classes of Lipoproteins by increasing density:
1. Chylomicrons (CM) 2. Very low density (VLDL) 3. Intermediate density (IDL) 4. Low density (LDL) 5. High density (HD)
43
What is are the TAGs & cholesterol esters surrounded by ?
Polar outer phospholipids shielding them from water
44
What is used to synthesise their membranes ?
Cells use fats and cholesterol to synthesise their membranes
45
TAGs cannot be absorbed by? but are broken into ?
TAGs cannot be absorbed by intestine, they are broken down into free fatty acids & glycerol by pancreatic lipase & colipase: The activated complex works only at a water-fat interface Must be emulsified by bile salts for excretion
46
What is the main function of bile acid ?
The main function of bile acid is to facilitate the formation of micelles, which promotes the processing of dietary fat
47
Bile salts are ?
Amphipathic molecules & very effective detergents
48
What do Bile Salt act to solubilise ?
They act to solubilise dietary lipids & also the lipid-soluble vitamins A, D, E and K
49
Soaps are ?
Salts of TAGs formed by breakdown in a strong base (saponification)
50
Solubility in water and grease/oil in a long non-polar hydrophobic hydrocarbon chain ?
Insoluble in water but soluble in grease/oil
51
Short polar carboxylate ion is? solubility in water and grease/oil ?
Short polar carboxylate ion is hydrophilic - water soluble but insoluble in grease/oil
52
Non-polar tails dissolve in?
Grease/oil surrounding a dirt particle & disperse or emulsify the particles which are then washed away
53
What are waxes ?
Carboxylic acid esters of long chain (C14-C36) saturated & unsaturated fatty acids with long chain alcohols (C16-C30)
54
Insoluble with high melting points involved in:
- storage of metabolic fuel in plankton - protection & pliability for hair & skin in vertebrates - waterproofing of feathers in birds - protection from evaporation in tropical plants and ivy - used by people in lotions, ointments, and polishes
55
Triacontanoylpalmitate, major component of beeswax, is ?
An ester of palmitic acid with the alcohol triacontanol
56
Waxes form ?
Protective coats on leaves / fruits and on birds & mammals. Bees use wax in the construction of their larval chambers
57
Biological waxes e.g. lanolin/beeswax & Carnuba wax (palm) are widely used in?
Lotions, ointments & polishes
58
What are sterols ?
Structural membrane lipids with 4 fused carbons
59
Cholesterol and related sterols are present in ?
The membranes of most eukaryotic cells - modulate fluidity and permeability - thicken the plasma membrane - no sterols in most bacteria
60
Mammals obtain cholesterol from ?
Food or synthesise it de novo in the liver
61
Cholesterol, bound to proteins, is transported to ?
Tissues via blood vessels | - Cholesterol in low-density lipoproteins tends to deposit and clog arteries
62
Many hormones are derivatives of ?
Sterols
63
What cannot synthesise sterols ?
Bacteria cannot synthesise sterols
64
Vitamin D is derived from?
Vitamin D is derived from cholesterol in a series of reactions, one of which requires UV light to break the bond between two C atoms
65
Steroids are oxidised derivatives of ?
Sterols
66
Steroids have the ? but lack?
Steroids have the sterol nucleus but lack the alkyl chain found in cholesterol
67
Steroids are more polar than?
Cholesterol
68
Steroid hormones are synthesised from ?
Cholesterol in gonads and adrenal glands
69
How are they carried through ?
They are carried through the body in the bloodstream, usually attached to carrier proteins
70
Many of the steroid hormones are ?
Male and female sex hormones

Biological Chemistry (15 decks)

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