Second Half I F24: Lecture Slides 1 - 19 Flashcards
What are lipids defined by?
Their hydrophobicity (not by their chemical structure)
What do we use to dissolve lipids?
Organic Solvents
What is the organic solvent we use to dissolve lipids?
Typically a 2:1 mixture of Chloroform and Methanol
What are triglycerides?
Fats and Oils
What are the functions fo triglycerides?
Energy storage (use when needed)
What are the functions of phospholipids and sterols?
Structural elements of biological membranes
What are the functions of steroid hormones and prostaglandins?
Signal Transduction (cell-cell communication)
What is Coenzyme Q?
A mitochondrial electron transport chain
What is the function of coenzymes?
Enzyme cofactors
What are Vitamins A, D, E and K?
Lipids
What is the function of carotene?
Light-absorbing Pigment
What are glycolipids?
Contain both sugar and lipid portions and are important constants of cell membranes
What are the human blood types?
(O,A,B) are defied by the glycolipids displayed on the outer surfaces of blood cells.
What are lipoproteins?
VLDL, HDL, LDL (defined by density, transport blood in lipids)
Plasma lipoproteins that are associated with cardiovascular health and disease.
What are there three types of lipids we’re looking at?
1.) Fatty Acids
2.) Triacylglycerides
3.) Phosphoglycerides
What are fatty acids?
- Building blocks of many complex lipids
- Central Intermediates in Metabolism but not freely found in the environment or in cells (always conjugated)
What are Triglcyerides?
A storage fat
What are phosphoglycerides?
The major lipids in membranes
What are the characteristics of Fatty Acids?
They are a carboxylic acid with hydrocarbons ranging from 4-36 carbons
What are saturated fatty acids?
No double bonds between carbons in the chain (all single bonds)
What are unsaturated fatty acids?
Fatty Acids with one or more double bonds
When labelling fatty acids, which carbon is number 1 assigned to?
The carboxyl carbon is C-1
What are features of commonly occurring fatty acids?
- Have an even number of carbon atoms
- Are unbranched
What configuration are the double bonds in a fatty acid found in?
Cis transformation, which introduces a kink in the chain.
What are the double bonds in polyunsaturated fatty acids (PUFA)?
Methylene Bridged, not conjugated.
What are PUFA separated by?
By a methylene carbon and therefore the bond pattern is double-single-single-double (not conjugated)
What fatty acid would not be an important constituent in human nerve cells?
An odd number of carbons
What are the Five Commonly Occurring Saturated Fatty Acids Trivial Name and the number of Carbons?
12 Laurate
14 Myristate
16 Palmitate
18 Stearate
20 Arachidate
“Let My Pal Stay Around”
What can the process of partial hydrogenation of unsaturated fatty acids do?
It is used in manufacturing margarine and similar products to isomerize double bonds, generating trans fats
What does a Trans double bond allow a fatty acid to do?
Adopt an extended conformation, which can have serious negative effects on cardiovascular health.
What is partial hydrogenation?
Take double bonds and add hydrogens
What does the saturated chains extended conformation cause?
Them to pack in a fairly orderly way (causing extensive favourable interactions)
For saturated fatty acids what happens as the chain length increases?
Melting Point Increases and Solubility Decreases
How do unsaturated fatty acids pack and why?
Less regularly due to the kink caused by the cis double bond, lowering the number of favourable interactions.
What is the melting point of unsaturated fatty acids?
Drastically lower as less thermal energy is required to disrupt ordered packing and the fluidy of the membrane depends on this.
Why can trans fatty acids pack more regularly than cis forms?
Due to their extended nature, trans form shows a higher melting point.
What is the melting point of the saturated fatty acid Stearic Acid?
+70 degrees celsius
What is the melting point of the unsaturated fatty acid Linoleic Acid?
-5 degrees celsius
What do carboxylic acids form when combined with alcohols?
Esters
What do carboxylic acids form when combined with acids?
Acid Anhydrides
What are majority of fatty acids in biological systems found in?
The form of triacyglycerols
How are triaglycerols formed by?
Linking three fatty acids to a glycerol molecule through ester linkages.
What are TAGs the major constituent of?
Bulk fats and oils, including the human body’s depot fat.
What are some characteristics of triacylglcdyeride?
Highly hydrophobic as the polar carboxylic acids of the fatty acids are tied up as (less polar esters)
What does the melting point of TAGs depend on?
The length and degree of saturation of their fatty acid constitutes
Will you be asked to draw a triacylglyceride?
Yes.
What is a simple TAG
Same fatty acid in all three positions
What is a mixed TAG
2 or 3 different fatty acids
What is the MP and Unsaturation of a Solid TAG?
M.P increases
Unsaturation decreases
What is the MP and Unsaturation of a liquid TAG?
MP decreases
Unsaturation Increases
