Lipids Flashcards
What are lipids soluble in
What are the not soluble in
Water insoluble molecules that are soluble in organic solvents
What are lipids roles
In membranes
Energy storage
Signaling
In fat soluble vitamins
What are fatty acids
What are they used for
Chain of carbons with carboxylic acids groups at the end
fuel in metabolism
Building block for membrane lipids
What is better, cis or trans fatty acids
Trans because they can be closer together to other fatty acids
Fatty acids have both ______ and ______
Names
Common
Systematic
If it has 18 carbons and is a double bond what is the systematic name for this fatty acid
Octadecenoic acid
What if the effect of a double bond being closer to the head of a fatty acid
The impact is big
What’s another way to name fatty acids
Using ratios
Ex. Octadecatrienoic acid has a ratio of 18:3
(18 carbons: 3 double bonds)
What is the omega carbon in a fatty acid
The very last carbon at the end of the hydrocarbon chain (not the COOH end)
Start from this and count to the double bond to find the position of the db
How do we name fatty acid that have double bonds
See if cis or trans
Found where db is (from omega end)
Name the chain
Ex. If db is at carbon 9 and cis
cis-triangle^9-octadecenoate
What is special about fatty acids in animals
There usually an even number of carbons In The chain
16 and 18 carbon chain are most common
Double bonds are usually separated by at least one methylene (ch2) group
Usually cis db
What do the properties of fatty acids and the lipids derived from them depend in
depend on their chain length and degree of unstaruation (number of db)
What affects the melting point of fatty acids
Why
If comparing two fatty acids, The longer chain has a higher melting point if both have same amount of unsaturated
The more unsaturated (more db) has lower melting point
Vanderwaals as well as kinks that make it not so tightly packed and reduces the hydrophobic interactions
What part of a fatty acid has the most affect on its melting point
The amount of double bonds has more affect than the length of the chain
This melting point changes much more if double bonds
What fatty acids can humans not make
What do they do
The omega 3 fatty acids
They are precursors to some hormones and polyunsaturated
They protect against heart disease (ex. EPA fatty acid and DHA fatty acid)
Memorize slide 14 in I pad pics
MEMORIZE
What does alpha indicate in example alpha linolenate
What about gamma
Omega 3
Omega 6
What are fatty acids stored as in the body and why
Storage as triacylglycerols (3 fatty acids, glycerol backbone) held together by ester bonds
They are neeeded as an energy source but their concentrations in the cells/blood are low since they’re acids
What are triacylglycerols
How are they stored
They are hydrophobic, almost anhydrous (don’t contain water)
Stored in specialized adipose cells (also for mobilization)
Adipose cells also provide insulation
What are glycerolipids
Made of four things:
2 fatty acids
Glycerol backbone
Phosphate attached to the back bone (negative charged)
(Head group) Alcohol attached to the phosphate
What are sphingolipids
They can pack more tightly together than glycerolipids
They can form hydrogen bonds
The only difference of them compare to glycerolipids is that they’re backbone is a sphingosine and only one fatty acid chain bound to the amide group
What are glycolipids
Lipids that have a sugar (glucose or galactose) instead of just a regular head group
Ex. Cerebroside (if one sugar)
What are phosphoglycerolipids
The simplest phospholipids
Same as glycerolipids, but not alchohol head group (something other than alcohol
Anything with “phosphatidyl” before the head group
What is PS charge
-1
What is PE charge
What is it lacking
What can it do
Neutral
Has no COOH group on its head group
H bond
What is PC charge
What is special about it
Neutral
Has three methyl groups on its head nitrogen (bigger head group)
What is PI charge
What’s special
-1
It has a head group in a chair conformation
What is diphosphotidylglycerol (CL)
Type of phospohyglycerolipid
Has 4 side fatty acid chains and glycerol back bone in the middle
Has -2 charge
What are steroids
They’re important for membrane fluidity
Not in prokaryotes but In all animal membranes
Ex. Cholesterol
What does cholesterol do to the membrane
What does it have to do
It has a large bulky non polar tail and a tiny oh head group
This makes it rigid and decreases fluidity of the membrane
It has to go deeper into the membrane so that the large hydrophobic rings don’t interact with the polar groups of the membrane surface.
It has to anchor itself into the membrane
What are lipid vesicles or “liposomes”
The bilayer has an outer and inner aqueous compartment and forms a circle with water inside
PC is more likely in the outside because it has a large head group
PE is more likely on the inside because of small head group
What is special about the curvature of liposomes
The curving is different depending on the size of the liposome
And the curving affects how the lipids in the lipsome pack
