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Biochemistry 301 > Chapter 9 - Lipids > Flashcards

Chapter 9 - Lipids Flashcards

1
Q

Hydrolyzable Lipids

A

Traiglycerols (fats and oils); waxes; glycerophospholipids; sphingolipids (spingophospholipids and sphingoglycolipids)

Assembled from various components - fatty acids combined with other groups: glycerol-based or sphingolipids

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2
Q

Non-hydrolyzable lipids

A

Steroids; eicosanoids; fat-soluble vitamins

cannot break down to simpler components

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3
Q

Palmitic Acid

A

C16:0

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4
Q

Stearic Acid

A

18:0

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5
Q

Oleic Acid

A

18:1 (9)

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6
Q

Linoleic Acid

A

18:2 (9, 12)

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7
Q

Alpha linolenic acid

A

18:3 (9,12,15)

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8
Q

Essential fatty acids

A

only obtained via diet (not produced)

Linoleate and linolenic acid

Role: precursors of prostalglandons, eicosanoids, epidermal lipids

membrane lipids

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9
Q

Tricylglycerols (TAGs)

A

3 fatty acyl residues esterfied to glycerol

Neutral and extremely nonpolar (great for energy storage!)

Anhydrous and highly reduced (major component of adipose tissue - tight packing)

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10
Q

Glycerophopholipids

A

highly amphipathic molecules: 2 fatty acids linked to glycerol-3-phosphate via ester linkages

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11
Q

Common polar head groups

A

ethanolamine, choline, serine

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12
Q

Plasmalogens

A

glycerol backbone

one ester-linked fatty acid

one vinyl-ether linked fatty acid

concentrated in CNS membranes; muscle, and peripheral nerve tissue

most common head group: choline or ethanolamine

possible function: protecs cell components from oxidative damage (free radicals) via vinyl ether linkage

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13
Q

Sphingolipids

A

sphingosine backbone (has amine); abundant in CNS of mammals

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14
Q

Steroid

A

Precursor: isoprenoid units and squalene

four fused rings, nearly planar structure, very hydrophobic

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15
Q

Cholesterol derivatives (features)

Cholesterol esters; bile salts; hormones; certain vitamins (solubility, rigidity, near planar shape)

A

Shape & functional group arrangement complementary to receptor, aid in digestion of lipids

Nonpolar allows it to get through membrane (some amphipathic)

signaling molecules, non-hydrolyzable, can mix and match rings to get new flavors

ex: stigmasterol (plant sterol); testosterone (steroid hormone); sodium cholate (bile salt); ergosterol (sterol from fungi and yeast)

fat soluble vitames (a, d, e) (a = retinol)

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16
Q

Cholesterol as related to membrane fluidity

A

Decreases membrane fluidity because its rigid steroid ring system interferes with the motions of the fatty acid side chains in other membrane liips

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17
Q

Fluidity of membranes as related to temperature

A

Fluidity is temp. dependent

At membrane “meltting point” -> transition from ordered crystalline state (gel) to fluid

Solid: Van der waals packing but free rotation; thicker due to stiff, extended tails

To maintain the fluid, dynamic structure: alter fatty acid content of membranes

18
Q

Basic features and components of other fatty-acid based lipids

e.g. waxes, eicosanoids, and fat-soluble vitamins (some derived from cholesterol)

A

Waxes: esters of long-chain fatty acids and long-chain monohydroxide alcohols (insoluble in H2O; high mp)

protective waterproof coating on leaves, fruits, skin, etc

Eicosanoids: derived from arachindonic acid; oxygenate variations. Signal molecules: bind to enzymes or proteins for response

Fat-soluble vitamins: A (retinol), E (antioxidant), K (nonpolar lipids)

19
Q

Functions of Lipids

A

energy storage, insulation, cushioning

cell compartmentalization

hormones and signaling

20
Q

Melting Point

Effect of shorter tails and more double bonds

A

shorter tails - fewer van der waals interactions -> lower melting temp.

more double bonds- more kinking of fatty acid tail ->lower melting temp.

21
Q

Sphingosine

A

C18 amino alchol: C1-OH; C2-NH2; C3-OH

22
Q

Ceramindes

A

basis of all sphingolipids; fatty acyl group linked to C2 by an amide bond

23
Q

Sphingomyelins

A

contains phosphate (only sphingolipid)

phophocholine or ethanolamine at ceramide C1

membrane component (about 10-20% of plasma membrane in lipids)

24
Q

Cerbrosides and Gangliosides

A

carboyhydrate instead of phosphate at C1 (no phosphate)

25
Q

Glycosphingolipids

A

complex

specific tissues and locations in cells

no phosphate, only carbohydrate linked to C1-OH

26
Q

Cerbrosides

A

monosaccharide at C1 of ceramide (glucose, glactose, etc)

27
Q

Gangliosides

A

ceramide with branched oligosaccharide at C1

lots of types found on cell surface about 6% of brain lipids

membrane signal and markers

problems with degradation responsible for Tay-Sach’s and similar diseases

28
Q

Membrane Rafts

A

near crystalline regions rich in sphingolipids and cholesterol

polar head h-bond

cholesterol fills gaps between tails

more crytalline

entire raft diffuses laterally

29
Q

Fluid Mosaic Model

A

olive-oil river, protein-filled treas, sugary skies

storm, crazy. Rafts appear and gone. Trees receive quick signals.

Ions whiz around and dive in and out of river.

Traffic is dizzy. Border is cell membrane. (50% of membrane is proteins)

30
Q

Protein functions

A

signaling

communication

transport

metabolic rxns

membrane rearranging

31
Q

Asymmetric distribution of membrane lipids

A

glycolipids and glycoproteins one extracellular face

asymmetry arises from lipid synthesis in the endoplasmic reticulum (plasma membrane in bacteria) by integral membrane proteins mostly on one face.

32
Q

LIpid composition between leaflets modulated by..

A

enzyme activity

flippases: transport across membrane by facilitated diffusion

phospholipid traanslocases: active (atp driven) phospholipid transport across bilayer

non-random phospholipid distribution (communicates cell status or type)

33
Q

Peripheral

A

soluble, globular proteins associated with membrane; dissociated by high ionic strenth or pH changes

34
Q

Integral/intrinsic

A

inserted into or transverse membranes: removed by detergents or chaotropic agents

span membrane with an amino acid sequence specific to membrane proteins

35
Q

Lipid-linked

A

covalent linkage to lipid group inserted into the membrane.

36
Q

Alpha helix in membrane as transverse thing

A

satisfies all polar gorups with h-bonding

interacts favorably with nonpolar membrane interior

interactions between helices could be polar

37
Q

Two distinct regions of integral proteins

A

region emerging from membrane: globular with hydrophobic core. Exterior of cell: modified with glycosylations. Interior of cell: polar with neg. and pos. charged regions

inside of membrane -> hydrophobic surface (few polar groups with associated H2O)

ex. Glycophorin

38
Q

Hydropathy plot

A

identifies transmembrane helices in proteins

39
Q

B-Barrel

A

possible polar interior/hydrophobic exterior

2-22 strands (max. H-bonding - satisfies polar backbone groups)

Barrel exterior (band of hydrophobic residues -interior of membrane)

hydrophobic band flanked by aromatic aa - interact with polar heads.

may be monomers or trimers

allow entry of small, polar molecules…can increase specificity by changing the residues.

40
Q

Linkage of Peripheral protein to membrane surface

A

Noncovalent - h-bonds and charge-charge interactions

Covalent links from amino acids to lipids -> S, N, or O- linked to amino acids (ex. Cys, Lys, Ser)

Biochemistry 301 (10 decks)

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