Lipids & Fatty Acids

Question 1

Lipids & Fatty Acids Facts

Answer 1

Insoluble in water
Usually have an even # of Carbons
Principal form of storing energy
Play crucial roles in cellular functions

Question 2

Structure

Answer 2

Polar head with long hydrocarbon chain
Can be fully saturated (no double bonds)
Can be unsaturated (double bonds —> less H)

Saturated with Hydrogens

Question 3

Nomenclature

Answer 3

Alpha Carbon is C1, number to the left
If 20 carbons with one double bond = 20:1 (delta #C)

**If there is a double bond at C3 &/or C6 it is an OMEGA FA (w-3 for both or C3, w-6 only at C6)

Question 4

Melting Points of FA

Answer 4

Longer chains = HIGHER melting point
More “kinks” = very LOW melting point
Why? Saturated chains pack tightly together = more stable = harder to break bonds
Unsaturated (with kinks) can’t pack as tightly

Question 5

Solubility of FA

Answer 5

Longer chains = lower solubility

More double bonds = higher solubility

Question 6

Triacylglycerols

Answer 6

Contain a Glycerol (3 OH groups off a 3 Carbon chain)
Contain 2 or 3 FA chains bound to the O groups (esterified)
Mixed- different FA chains
Simple - same FA chains
ENERGY STORAGE

Question 7

Lipases

Answer 7

Enzymes that catalyze hydrolysis of triacylglycerols

BREAK DOWN FATTY ACIDS for FUEL

Question 8

Olive Oil, Butter, Beef Fat

Answer 8

Olive Oil (liquid) has a low melting point which means it is made up of mostly UNSATURATED FA chains (kinks) 
Butter (soft solid) has a higher MP which means it has LESS unsaturated FA and more SATURATED FAs.
Beef Fat (hard solid) has the highest MP so it has the MOST SATURATED FAs and LEAST UNSATURATED

Question 9

Waxes

Answer 9

High melting points
Esters of long chain saturated/unsaturated FA bound to long chain alcohols
FA-ester-long chain-OH

Question 10

Lipid Types

Answer 10

1. Storage Lipids (Triacylglycerols)

2. Membrane Lipids

Question 11

Membrane Lipids

Answer 11

1. PHOSPHOLIPIDS
   a. Glycerophospholipids
   b. Sphingolipids
2. GLYCOLIPIDS
   a. Sphingolipids
   b. Galactolipids (plants)
3. Archaeal Ether Lipids (Archaea)

Question 12

Glycerophospholipids

Answer 12

Similar to triacylglycerol 
Glycerol backbone
2 FA chains
phosphate group
Head group (alcohol?)

Question 13

Phospholipid Sphingolipid

Answer 13

Two long hydrocarbon chains

• One from Sphingosine
• One from a FA BOUND TO THE SPHINGOSINE
• Phosphate
• Head Group (choline?)

Question 14

Sphingosine

Answer 14

FA chain with one double bond
Alcohol on C3
Amine on C2 (this is what FA binds to)
Alcohol on C1 (head group binding site)

Question 15

Glycolipid Sphingolipid

Answer 15

Same as a phospholipid sphingolipid in that there is one sphingosine, and one FA
Differs by a mono or oligosaccharide instead of phosphate-X

Question 16

Sterols

Answer 16

4 Fused Rings
Hydroxyl Group
Cholesterol