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2. wk > Struct. of Lipids > Flashcards

Struct. of Lipids Flashcards

1
Q

Describe different kind of lipid structures

A
  • hydrocarbon chain+ carboxyl group (COOH)
  • Cholesterol:
  • > polar head group (OH)
  • > Steroid nucleus
  • > Alkyl side chain
  • triglyceride:
  • has a glycerol backbone
  • head-group substituent
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2
Q

What is the difference between saturated and unsaturated fatty acids?

A
  • saturated fatty acids (s.a. palmitic acid) do not have a double bond
  • unsaturated fatty acids (s.a. linoleum acid) do have at least one double bond
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3
Q

In what way are lipids storage of energy?

A
  • Storage of energy:
  • Reduced compounds: lots of available energy
  • Hydrophobic nature: good packing
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4
Q

In what way do lipids help with the insulation from environment?

A
  • Low thermal conductivity
  • High heat capacity (can “absorb” heat)
  • Mechanical protection (can absorb shocks)
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5
Q

In what way are lipids water repellant?

A
  • Hydrophobic nature: keeps surface of the organism dry
  • Prevents excessive wetting (birds)
  • Prevents loss of water via evaporation (Verdunstung)
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6
Q

In what way do lipids help with Buoyancy control and acoustics in marine mammals?

A
  • Increased density while diving deep helps sinking (just a hypothesis)
  • Spermaceti organ may focus sound energy: sound stun gun?
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7
Q

What are some other functions of lipids? (Membrane structure, Cofactors for enzymes, Signaling molecules, Pigments, Antioxidants)

A

-Membrane structure
- Main structure of cell membranes
• Cofactors for enzymes
– Vitamin K: blood clot formation
– Coenzyme Q: ATP synthesis in mitochondria
• Signaling molecules
– Paracrine hormones (act locally)
– Steroid hormones (act body-wide)
– Growth factors
– Vitamins A and D (hormone precursors)
• Pigments
– Color of tomatoes, carrots, pumpkins, some birds
• Antioxidants
– Vitamin E

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8
Q

What are antioxidants?

A

-eine chemische Verbindung, die eine Oxidation anderer Substanzen verlangsamt oder gänzlich verhindert

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9
Q

What are canthaxanthin and zeaxanthin?

A

-are color
-> canthaxanthin: bright red
C40H52O2 (O bei stelle 3L und 0R ring)
-zeaxanthin: bright yellow
C40H56O2 (OH bei stelle 4L und 1R ring)

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10
Q

Which classification groups exist in lipids?

A
  • lipids contain fatty acids/ do not contain fatty acids (cholesterol, terpenes)
  • lipids contain fatty acids:
    1. storage lipids
    2. membrane lipids (1. Phospholipids, 2. Glycolipids, 3. Archaebacterial ether lipids)
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11
Q

How many carbons fo carboxylic acids with hydrocarbon chains contain?

A
  • 4 to 36
    (+ almost all natural fatty acids have an even number (grade Zahl of carbons)
    ->most natural fatty acids are unbranched
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12
Q

Give definition for monounsaturated and polyunsaturated

A

-Monounsaturated: one double bond between carbons in the
alkyl chain
• Polyunsaturated: more than one double bond in the alkyl chain

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13
Q

Give the nomenclature of greek alphabet

A
  • Α α, alpha, 1
  • Β, β, beta, 2
  • Γ, γ, gamma, 3
  • Δ, δ, delta, 4
  • Ε, ε, epsilon, 5
  • Ζ, ζ, zeta, 6
  • Η, η, eta, 7
  • Θ, θ, theta, 8
  • Ι, ι, iota, 9
  • Κ, κ, kappa, 10
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14
Q

Which role do Omega-3 fatty acids take in human’s life? Which are included?

A

-are essential nutrients
-Humans need them but cannot synthesize them
-Including ALA, DHA, and EPA
• Although DHA and EPA can be synthesized from ALA
->Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), Alpha-linolenic acid (ALA)

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15
Q

What can you say about the solubility and melting point of fatty acids?

A
  • Solubility:
  • decreases as the chain length increases
  • Melting Point:
  • decreases as the chain length decreases
  • decreases as the number of double bonds increases
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16
Q

Conformation (räumliche Anordnung) of fatty acids (incl. saturated, unsaturated chain)

A

-The saturated chain tends to adopt extended conformations
- The double bonds in natural unsaturated fatty acids are
commonly in cis configuration, which kinks the chain

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17
Q

Why do unsaturated cis fatty acids have a lower melting point?

A 
-It takes less thermal energy to disrupt disordered packing
of unsaturated fatty acids
->disordered: 
 due to the kink
– less-extensive favorable interactions
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18
Q

Are the saturated fatty acids ordered or less ordered?

A

-Saturated fatty acids pack in a fairly orderly way

–> extensive favorable interactions

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19
Q

What determines the membrane fluidity?

A

-mainly by the fatty
acid composition
->More fluid membranes require shorter and more
unsaturated fatty acids:
-At higher temperatures cells need more saturated fatty
acids
– To maintain integrity
• At lower temperatures cells need more unsaturated
fatty acids
– To maintain fluidity

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20
Q

How is a trans fatty acid formed? What does it increase?

A

-by partial dehydrogenation of
unsaturated fatty acids
-Done to increase shelf life (Haltbarkeit) or stability at high temperature of oils used in cooking (especially deep frying (frittieren) )
->Trans fatty acids can pack more regularly and show
higher melting points than cis forms

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21
Q

What does a trans double bond allow a given fatty acid?

A

-to adopt an extended conformation

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22
Q

What are Triacylglycerols? How are solids/ liquids called? Solubility in comparison of fatty acids ; density in comparison of water

A

-Nonpolar
–The primary storage form of lipids (body fat)
-Majority of fatty acids in biological systems are found
in the form of triacylglycerols
-Solid ones are called fats
-Liquid ones are called oils
-Less soluble in water than fatty acids due to the lack
of charged carboxylate group
-Less dense than water: fats and oils float

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23
Q

What are the advantages of fats over polysaccharide?

A

-Fatty acids carry more energy per carbon because
they are more reduced
-Fatty acids carry less water per gram because they
are nonpolar
-Glucose and glycogen are for short-term energy needs,
quick delivery
-Fats are for long-term (months) energy needs, good
storage, slow delivery

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24
Q

What are waxes?

A

-Waxes are esters of long-chain saturated and unsaturated fatty acids with long-chain alcohols

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25
Q

What are waxes properties?

A

-Insoluble and have high melting points

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26
Q

Name variety of functions for waxes

A
  • Storage of metabolic fuel in plankton
  • Protection and pliability (Biegsamkeit) for hair and skin in vertebrates (Wirbeltiere)
  • Waterproofing of feathers in birds
  • Protection from evaporation (Verdunstung) in tropical plants and ivy (Efeu)
  • Used by people in lotions, ointments, and polishes
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27
Q

Describe the structure of lipids in membranes

A

-are polar
-Contain polar head groups and nonpolar tails (usually
attached fatty acids)

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28
Q

Where can diversification in lipids in membranes come from?

A
  • modifying a different backbone
  • changing the fatty acids
  • modifying the head groups
29
Q

What does determine the surface properties of membranes?

A

-the properties of head groups

->Different organisms have different membrane lipid
head group compositions
->Different tissues have different membrane lipid
head group compositions

30
Q

What is glycerophospholipids? How is it constructed?

A

-Primary constituents of cell membranes
-Two fatty acids form ester linkages with the first and second
hydroxyl groups of L-glycerol-3-phosphate
-Unsaturated fatty acids are commonly found connected to C2
-Head group is charged at physiological pH
(The highly polar phosphate group may be further esterified by an
alcohol; such substituent groups are called the head groups)

31
Q

Name some examples of glycerophospohlipids

A

-Phosphoatidic acid : x= -H charge at ph7 (-2)
-Phosphatidylethanolamine: ethanolamine x= -NH3 charge at ph7 (0)
-Phosphatidylcholine choline : x= -NH3
charge at ph7 (0)
-phosphatidylserine serine
charge at ph7 (-1)
-phosphatidylglycerol
charge at ph7 (-1)

32
Q

What is Phosphatidylcholine?

A

-the major component of most eukaryotic cell membranes
-Many prokaryotes, including E. coli, cannot synthesize this
lipid; their membranes do not contain phosphatidylcholine

33
Q

What is Plasmalogen? Where is it common? What are the functions?

A

-Vinyl ether analog of phosphatidylethanolamine
-Common in vertebrate heart tissue
• Also found in some protozoa and anaerobic bacteria
• Function is not well understood
– Resistant to cleavage (Spaltung) by common lipases (feat spaltendes enzyme) but cleaved by few specific lipases
– Increase membrane rigidity (Steifigkeit) ?
– Sources of signaling lipids?
– May be antioxidants?

34
Q

What is sphingolipids backbone?

A

-backbone is not glycerol it is a long-chain amino alcohol sphingosine

35
Q

How is fatty acid joined to sphingosine? How is a polar head group connected to sphingosine?

A
  • via an amide linkage (rather than en ester linkage (as usually seen in lipids))
  • A polar head group is connected to sphingosine by a glycosidic or phosphodiester linkage
36
Q

Where are the sugar- containing glycosphingolipids found?

A

-largely in the outer face of plasma membranes

37
Q

How is a sphingomyelins constructed?

A

-Ceramide (sphingosine + amide-linked fatty acid) +

phosphocholine attached to the alcohol

38
Q

Where is sphyingomyeling abundant?

A

-myelin sheath that

surrounds some nerve cells in animals

39
Q

How are blood groups determine in parts?

A
  • by the type of sugars located on the head groups in glycosphingolipids
40
Q

How are the structure of sugar determined?

A

-by an expression of

specific glycosyltransferases

41
Q

Which individual have the 0 antigen? Which have blood group A? Which have a blood group B?

A

-Individuals with no active glycosyltransferase will have the O antigen
– Individuals with a glycosyltransferase that transfers an N-
acetylgalactosamine group have A blood group
– Individuals with a glycosyltransferase that transfers a galactose
group have B blood group

42
Q

What is the tay-sachs disease?

A

-(also known as GM2 gangliosidosis or hexosaminidase A deficiency ) is a rare autosomal recessivegenetic disorder (needed for GalNAc)
-In its most common variant (known as infantile Tay–Sachs disease), it causes a
progressive deterioration (Verschlechterung) of nerve cells and of mental and physical abilities that begins around 7 months of age
and usually results in death by the age of four

43
Q

What is Gaucher’s disease?

A 
-Gaucher's disease or Gaucher disease (GD) is a genetic disorder in
which glucocerebroside (a sphingolipid, also known as glucosylceramide (Glc)) accumulates (anhäufen) in cells and certain organs
-The disorder is characterized by bruising (blutergüsse), fatigue,anemia, low blood platelet count and enlargement of the liver and spleen (Milz)
44
Q

What is the Sandhoff disease?

A

-also known as Sandhoff-Jatzkewitz disease, variant 0 of GM2- Gangliosidosis or Hexosaminidase A and B deficiency, is a lysosomal genetic, lipid storage disorder caused by
the inherited deficiency to create functional beta-hexosaminidases A and B -Accumulation of these metabolites leads to a progressive destruction of the central nervous system and eventually to death

45
Q

What is the Fabry disease?

A
  • also known as Fabry’s disease, Anderson-Fabry disease, angiokeratoma corporis diffusum, and alpha-galactosidase A deficiency
  • is a rare genetic lysosomal storage disease, inherited in an X- linked manner
  • Fabry disease can cause a wide range of systemic symptoms
46
Q

What is the Niemann–Pick disease?

A

-is a group of inherited, severe metabolic disorders in which sphingomyelin accumulates in lysosomes in cells
-Accumulation of sphingomyelin in the central nervous
system (including the cerebellum) results in unsteady gait (ataxia) (Gangart), slurring of speech (dysarthria) (Sprachverwirrung), and difficulty in swallowing (dysphagia)

47
Q

What do dysfunctions in Basal ganglia cause?

A

-causes abnormal posturing of the limbs, trunk, and face

dystonia

48
Q

What do upper brainstem disease cause?

A

-disease results in impaired voluntary rapid eye movements (supranuclear gaze palsy)

49
Q

What do more widespread disease involving the cerebral cortex and subcortical structures cause?

A

-causes gradual loss of

intellectual abilities, causing dementia and seizures (Anfall)

50
Q

How is sterol constructed?

A
  • Steroid nucleus: four fused rings
  • Hydroxyl group (polar head) in the A-ring
  • Various nonpolar side chains
  • The steroid nucleus is almost planar
  • ->many hormones are derivatives of sterols
51
Q

Where are cholesterol and related sterols present? +functions

A

-Cholesterol and related sterols are present in the

membranes of most eukaryotic cells

52
Q

From where do mammals obtain cholesterol?

A

-from food or synthesize it de novo in the liver

53
Q

How is cholesterol transported and where?

A

-Cholesterol, bound to proteins, is transported to
tissues via blood vessels
-Cholesterol in low-density lipoproteins tends to deposit (abzuschneiden) and clog arteries

54
Q

What do sterols and hopanols increase?

A

-membrane rigidity (steifigkeit) and permeability (Durchlässigkeit)

55
Q

Cell membranes of which type contain sterols/ hopanols?

A 
Cell membranes of many
eukaryotes contain sterols
– Cholesterol in animals
– Phytosterols in plants
– Ergosterol in fungi
-Cell membranes of aerobic
prokaryotes contain hopanols
56
Q

What are steroid hormones? How are they carried in the body?

A

-Steroids are oxidized derivatives of sterols
-They are carried through the body in the
bloodstream, usually attached to carrier proteins
• Many of the steroid hormones are male and female sex hormones

57
Q

How do steroid hormones differ form cholesterol?

A

–Steroids have the sterol nucleus, but lack the alkyl
chain found in cholesterol
-More polar than cholesterol

58
Q

Name the types of steroid hormones

A

-testosterone, cortisol, prednisone, b-estradiol, aldosterone, prednisolone, brassinolide (a brassionsteroid)

59
Q

What is created if arachidonic acid is metabolized? What does arachidonic acid yield if it is enzymatic oxidized?

A
  • signaling lipids
  • Prostaglandins (inflammation (entzündung) and fever)
  • Thromboxanes (formation of blood clots)
  • Leukotrienes (smooth muscle contraction in lungs)
60
Q

What does PGH2 have twice?

A

-isoforms
-COX-1 catalyzes synthesis of prostaglandins that regulate gastric mucin secretion (Magenschleimsektion)
• COX-2 catalyzes synthesis of prostaglandins that mediate pain, inflammation, and fever
–> NSAIDs (Aspirin, Ibuprofen, Acetaminophen)
inhibit COX-2

61
Q

What can block the formation of prostaglandins and thromboxanes
from arachidonate?

A

-Nonsteroidal antiinflammatory drugs (NSAIDs) such as aspirin and ibuprofen can block by inhibiting the enzyme cyclooxygenase (prostaglandin H2 synthase).

62
Q

How does the blocking of the formation of prostaglandins and thromboxanes
from arachidonate exactly work?

A 
-Aspirin (Acetylsalicylate) is an irreversible
inhibitor
-Acetylates a Ser in active site
-Blocks active site in both COX isozymes
•Ibuprofen and naproxen are competitive
inhibitors
-Resemble substrate, also block active site in
both isozymes
63
Q

Name a Few NSAIDs that Inhibit PGH2

A

-aspirin, salicylate, ibuprofen, naproxen

64
Q

Tell a little bit about the story of COX-2 specific inhibitors history

A

-Developed to inhibit prostaglandin formation
without harming stomach
• Includes Vioxx, Bextra, and Celebrex
• Vioxx and Bextra removed from market due to
increased rates of stroke and heart attack
– May disrupt balance between blood-thinning
prostacyclin and blood-clotting thromboxanes

65
Q

The importance of biologically active lipids

A

-Are present in much smaller amounts than storage or structural lipids
-Play vital roles as signaling molecules between nearby
cells
• Lipid soluble vitamins (A, D, E, and K)

66
Q

What does Vitamin D regulate?

A

-the calcium uptake (Calciumaufnahme)

67
Q

Vitamin A is involved in?

A
  • Vitamin A (Retinol) is Involved in visual pigment

- Precursor for other hormones involved in signaling

68
Q

What are Vitamin E,K and other lipid quinones (Lipidchione)?

A
  • antioxidants
  • Vitamin E an antioxidant
  • vitamin K a blood clotting cofactor (phylloquinone)
  • warfarin a blood anticoagulant
  • ubiquinone a mitochondrial electron carrier N= 4 to 8

2. wk (9 decks)

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