Lipids Flashcards
What are lipids?
Heterogeneous group of compounds
Can be extracted from tissue via nonpolar solvents
What is the importance of lipids?
15% of the human body
Source of energy
Component of membranes, vitamins, hormones, and other regulatory molecules
Important in atherosclerosis and obesity
How much free fatty acid exists in the body?
Practically none
A little is attached to albumin
What is a fatty acid?
Hydrocarbon chains of various lengths and degrees of unsaturation with carboxylic acid groups
How do you name saturated fatty acids?
Name parent hydrocarbon using number of carbons, then substitute “oic” at the end
How do you name mono- and polyunsaturated fats?
Mono = ending is -enoic
Two double bonds = dienoic
Three = trienoic
How are fatty acids named via the omega nomenclature?
Number of carbons: (Double bonds)n - (where the double bonds start)
E.g. Linoleic acid
18:2n-6
What are the classifications for short-, medium-, and long-chain fatty acids?
Short <6 carbons
Medium = 6-12
Long = 13-21
What are very long chain fatty acids?
22 or more carbons
but fatty acids that are more than 22 carbons long exist in a very small percentage in the body
How does chain length influence membrane fluidity?
Shorter chain length = More fluid
How does saturation influence membrane fluidity?
Less saturation = increases fluidity
What type of lipids are storage lipids?
Triacylglycerols
What is the function of triacylglycerides?
Provide stored energy and insulation, cushioning
Made of three fatty acid chains bound to a glycerol molecule
Where is the unsaturated fatty acid located on the tryglyceride molecule if there is one?
The second carbon
What are three advantages to using triglycerides as fuel?
Carbon atoms are more reduced
TG are unhydrated, less weight
Can also be used as insulation
What are three common types of membrane lipids?
Phospholipids
Glycolipids
Cholesterol
How are lipid bilayers formed?
Energetically favorable to remove hydrophobic fatty acids from water, so at a critical concentration, lipids spontaneously form micelles, bilayers, or liposomes.
Phospholipids prefer bilayers
What are four characteristics of membranes?
Non-covalent
asymmetric
fluid
electrically polarized
What are the four components of phospholipids?
Fatty Acids
Platform to attach the fatty acid
A Phosphate
An Alcohol
What is phosphatidate?
Simplest phospholipid
Made of 2 fatty acid hydrocarbon chains, glycerol and phosphoric acid
What are five common alcohol moieties?
Serine
Ethanolamine
Choline
Glycerol
Inositol
What are lysophospholipids?
Phospholipids with only one acyl group attached.
Could be either acyl group
What are plasmalogens?
Potent signaling lipids that are structurally similat to phosphotidylcholine or -ethanolamine
Contains an ether-linked alkene
What are sphingolipids?
Phospholipid that contains sphingosine as a backbone instead of glycerol
Includes sphingomyelins and glycosphingolipids
How do you differentiate sphingomyelin from other phospholipids?
The presence of an amide linkage
What are glycolipids?
Sugar containing lipids
NOT phospholipids
Derived from sphingosine
What is cholesterol?
Lipid based on a steroid nucleus
Makes membranes less fluid
