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Biochemistry - Real One > Lecture 11: Lipids > Flashcards

Lecture 11: Lipids Flashcards

1
Q

What is a lipid? What makes them hydrophobic?

A
  • Water insoluble molecules that are soluble in organic solvents. Common constituents of membranes. The key part of this is the fatty acids, which are what give it hydrophobic properties.
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2
Q

Describe fatty acids

A

Contribute to hydrophobicity, have various lengths of chains that always terminate with a Carboxylic Acid group. And are generally the building blocks of Phospholipids, and Glycolipids.

  • Their tails are often used to modify proteins
  • Stored as Triacylglycerols (TAG)
  • Derivatives can include hormones, signal molecules, and intracellular messengers.
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3
Q

How does one number fatty acids in a carbon chain?

A

Starting with the Carboxyl Terminus:

  • Carbon 2 is the alpha carbon, 3 is the beta carbon, last carbon in the chain is the omega carbon.
  • The double bond is represented (in the direction given) by the delta sign. So something like cis-delta9.
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4
Q

Describe the nomenclature for double bonds in fatty acids.

A
  • Dropping the e off the parent name, the acid ends in -oic.
  • No double bonds are octadecAnoic acid
  • One double bond is octadecEnoic acid
  • Two Double bonds is OctadecaDienoic
  • Three Double Bonds is OctadevaTrienoic
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5
Q

Give some properties about fatty acids

A
  • They usually contain an Even number of carbons between 14-24
  • Most Commonly between 16-18
  • Most double bonds are in Cis
  • Ionized at physiological pH so they’ll usually in carboxylate (palmitate, oleate) form.
  • Unsaturated has Lower melting points.
    Melting points increase with the chain length.
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6
Q

Describe Palmitate

A
  • 16 carbon fatty acid chain with no double bonds
    -Not an essential fatty acid
    also called n-Hexadecanoate
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7
Q

Describe Stearate

A

18 carbon fatty acid chain with no double bonds.
Not an essential fatty acid
- Also called n-Octadecanoate

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8
Q

Describe Palmitoleate

A

16 carbon fatty acid chain with one double bonds (usually at delta-9)
- Also called cis-delta9 Hexadecenoate

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9
Q

Describe Oleate

A
  • 18 carbon fatty acid with 1 double bond at delta-9

- Called cis-delta9-Octadecenoate

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10
Q

Describe Linoleate

A
  • 18 carbon fatty acid chain with 2 double bonds (at 9 and 12)
  • Omega-6 Essential Fatty Acid
  • Called cis,cist-delta9,delta12-Octadecadienoate
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11
Q

Describe Linolenate

A
  • 18 Carbon Fatty Acid Chain with 3 double bonds (9, 12, and 15)
  • Omega 3 Essential Fatty Acid
  • Sometimes called all cis-delta9, delta12, delta15-Octadecatrienoate
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12
Q

Describe Arachidonate

A
  • 20-carbon fatty acid chain with 4 double bonds.
  • Omega 6 Essential Fatty Acid
  • Sometimes called: all-cis-delta5,delta8,delta11,-delta14 Eicosatetraenoate
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13
Q

What is the name of that really tough organism they talked about in class?

A

Archaeon

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14
Q

Why is the archaeon so tough?

A

Within it’s membranes, it’s branches along the chains resist oxidation, and the phospho-ether bond greatly increases hydrolysis.

  • The ether linkage in the phophorylated side of the glycerol is more resistent to hydrolysis
  • The branched and saturated hydrocarbons are more resistant to oxidation.
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15
Q

What are the 3 major classes of membrane lipids

A
  • Phospholipids: Major class of membrane lipids, including phosphoglyceride and Sphingomyelin. Largest class of membrane lipids
  • Glycolipids: (Sugar containing lipids), Cerebrosides,
  • Cholesterol
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16
Q

What are the four components of a phospholipid?

A
  1. Fatty acid: provides a hydrophobic barrier
  2. A backbone to which fatty acids are attached - glycerol (3-carbon alcohol; phosphoglycerides) or a sphingosine (a more complex alcohol; sphingomyelin)
  3. a phosphate
  4. an alcohol attached to phosphate
17
Q

Why is phosphotidate important? (Be able to draw it)

A

Simplest type of phosphoglyceride that is used in the biosynthesis process of other phosphoglycerides.

Only a small amount of phosphotidates are actually in the membrane.

18
Q

What is phosphatidylserine important for? (Be able to draw it)

A

Phosphatidylserine: Important for memory and cognition

O-CH2-CH(COO-)(NH3+)

19
Q

What is phophatidylcholine found in?

A

Major constituent of cell membrane and pulmonary surfactant

-O-CH2-CH2-N(CH3)3

20
Q

What is phosphatidylethanolamine used for?

A

-O-CH2-CH2-NH3+

  • composing 25% of all phospholipids.
  • In human physiology, they are found particularly in nervous tissue such as the white matter of brain
21
Q

What is phosphatidyllinositol used for

A
  • important signaling and other functional activities in eukaryotic cell
  • Not gonna try to draw it but it’s squarish with a lot of alcohol groups.
22
Q

What is diphosphatidylglycerol used for?

A

Important component of inner mitochondrial membrane

  • Mirror image of 2 phosphatidates…sort of. Please don’t make me draw it right now?
23
Q

Describe sphingolipids (Be able to draw the sphingosine)

A
  • Derivatives of the C18 amino alcohol sphingosine
  • Sphingosine is an amino alcohol
  • Contains a long, unsaturated hydrocarbon chain
24
Q

List and describe the five types of sphingolipids

A
  • Ceramide = Sphingosine + Fatty Acid
  • Sphingomyelin = Ceramide + Phosphorycholine
  • Cerebrosides = Ceramide + Monosaccharides
  • Globoosides = Ceramide + Oligosaccharides
  • Gangliosides = Ceramide Oligosacharides, and NANA
25
Q

Describe Sphingomyelin (and also, draw that SOB)

A
  • The phospholipid with the sphingosine as the backbone.
  • The amino group of the sphingosine backbone is linked to a fatty acid by an amide bond
  • Found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons
  • Tips: Branch One: Alcohol Group off to the side, and 15 carbon chain with double bonds
    Branch Two: Amide + 15 carbon Chain
    Branch 3: Phosphocholine
26
Q

Describe Glycolipids

A
  • Sugar-containing lipids
  • Derived from sphingosine
  • Differ from sphingomyelin is the identity of the unit that is linked to the primary hydroxyl group of the sphingosine backbone (So that OH group on the first branch is going to be different in a glycolipid)
  • Oriented with the sugar residues always on the Extracellular side of the membrane
27
Q

Describe (and Draw) Cerebroside

A
  • The simplest glycolipid
  • Contains a single sugar residue
  • Cerebrosides is the common name for a group of glycosphingolipids called monoglycosylceramides
  • Important components in animal muscle and nerve cell membranes
  • Tips:
    Branch One - OH, and 15-carbon chain with double bond
    Branch Two - Amide Fatty Acid Unit
    Branch Three - O - Sugar (Either Glucose or Galactose)

Note: More complicated Cerebrosides (Such as Gangliosides) contain branched chains of up to seven sugar residues.

28
Q

Describe a cholesterol

A
  • A steroid, present in eukaryotes but not in most of prokaryotes, is built form 4 fused saturated hydrocarbon rings
  • Cholesterol is further classified as a sterol because of its C3-OH group and its branched aliphatic side chain of 8 to 10 C atoms at C-17
  • Jesus christ, do I really have to know how to draw that???
  • Look it’s a hydrocarbon ring, total of 27 carbons, An alcohol on the first ring (3rd Carbon), a methyl group between 1&2, and 3&4, and a branched chain at the last ring (17th carbon)
29
Q

Describe cholesterol in a biological setting

A
  • The most abundant steroid in animals
  • A major component of eukaryotic plasma membrane
    • essentially absent from some of the intracellular membranes
    • absent from prokaryotes
    • In membrane, cholesterol is oriented parallel to the fatty acid chains of the phospholipids, and the hydroxyl group interacts with the nearby phospholipid head group
  • The metabolic precursor of steroid hormones
  • Disrupts the tight packing of fatty acid chains in the membrane.

Biochemistry - Real One (25 decks)

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