Lipids Flashcards
How are lipids linked to other groups
Covalent bonds
What are the three lipid classes
Fatty acids
Triaclylglycerols
Phosphoglycerides
What are fatty acids
The building blocks of many complex lipids and are the central intermediates in metabolism
What are the molecular components of fatty acids
Are carboxylic acids with hydrocarbon chains
What is the difference between saturated and unsaturated fatty acids
Saturated: no c-c double bonds
Unsaturated: have one or more c-c double bonds
What does: 18:2 (^9,12) tell us about a certain fatty acid
18: the total number of carbons in the chain
2: the total number of double bonds
^9, 12 position of the 2 double bonds
What is partial hydrogenation
The artificial process in which fatty acids are made into trans fatty acids. Trans double bonds are added to the fatty acid to extend the chain and solidify it
Name the 5 main fatty acids and their number of carbons
Hint: Let My Pal Stay Around
Laurate: 12 Myristate: 14 Palmate: 16 Stearte: 18 Arachidate: 20
What are the solubility and melting point properties of saturated fatty acids
Since the chains pack in an ordered way, van der waals interactions are many. As chain length increases, melting point increases and solubility decreases
What are the melting point properties of unsaturated fatty acids
The kinks in the unsaturated fatty acid chains make it pack less regularly. Lowered melting point
Name two derivatives of fatty acids and their constituents
Esters : carboxyllic acids + alchol
Anhydrides: esters+ acid
What are triacyglycerols
Where the majority of fatty acids are stored: fat as we know it
How are triaglycerols
formed
3 fatty acids + 1 glycerol molecule through ester linkages
Why are triaglycerorols highly hydrophobic
The polar carboxyllic acids from the fatty acids are linked into esters
What is the difference between simple and mixed tricylglycerides
Simple: composed of the same fatty acid in all positions
Mixed: composed of 2 or 3 different fatty acids
what do you call the process of adding a phosphate and what does it do
Phosphorylation, it adds a negative charge to molecule and raises water solubility
Acetic acid + ethyl alcohol =
Phosphate ester
Acetic acid + acetic acid=
Acetic anhydride
Phosphoric acid + alcohol =
Phosphate
What is a phosphoglyceride
Are the primary constituents of biological membranes
What does amphipathic mean and why is it important
A combination of a hydrophilic head and a hydrophobic tail
All lipids are amphipathic and its why they can form lipid bilayers
Lipids aggregate in specific forms when in contact with water what are the three types
Micelles: small and roughly spherical, smallest and simplest
Bilayers: double layers of phospholipids. They can fold over to form vesicles. Since their tails are too large to form micelles
Vesicles
What does chiral mean
Two molecules that are asymmetric in such a way that the structure and mirror image are superimposable
What are enantiomers
Molecules that are mirror images of each other differ in configuration at every chiral atom
Have identical chemical properties and a plane of polarized light is passed through a solution of two is bent in opposite directions
What are diasteriomers
Monosaccharides with more than one chiral carbon atom do not have identical. Chemical properties
What are D and L sugars
L and d glucose are complete mirror images of each other exept the direction of the OH group
D: right
L: left
Most sugars are d sugars
What are the functions of lipids
Energy storage: triacylglycerols Structural elements of biological memberanes: phospholipids and sterols Enzyme cofactors: coenzyme q Vitamins: D A E K Light absorbing pigments: carotene Insulation and waterproof coating
How are lipid molecules different from proteins, carbs and nucleic acids
The rest have a defined structure, but lipids are defined by their hydrophobicity
What are the limits of iodine numbers of lipids
> 70 are oils,
What are the structural properties that determine the melting temperatures of various fatty acids
Chain length and degree of unsaturation
Why are unsaturated fatty acids most stable
In the extended form, they pack tightly together van der waals forces are many so lots of energy needed to break bonds = high melting points
If cis double bonds lower the melting point, why do the presence of trans double bonds raise the melting point
Trans double bonds do not change the geometry of the chain much
What structural property of a lipid allow them to be the main components of biological membranes
Their amphipathic property allows them to aggregate into bilayers
Why are triaglycerols such a good source of fuel
They are insoluble, so large amounts can be stored in cells without increasing the osmotic pressure in cytosol
