lecture 6 lipids Flashcards
lipids
Lipids are defined as molecules that are not soluble in water, but are soluble in organic solvents. They are hydrophobic (e.g. fats, oils, waxes) or amphipathic (e.g., fatty acids, phospholipids, glycolipids, steroids)
5 classes of lipids
Free fatty acids: A common fuel. Triacylglycerols: Fats and Oils, storage form of fatty acids. Phospholipids: Membrane lipids. Glycolipids: Membrane lipids composed in part of carbohydrates. Steroids: hydrocarbons with four rings (e.g., estrogens, androgens, cortisone, cholesterol, bile acid)
fatty acids are a main source of ___
fuel
Most fatty acid chains are ___ carbons in living system
16 or 18 carbons, always in even numbers
chains with double bonds are (saturated/unsaturated) with hydrogens
unsaturated
chains with no double bonds are (saturated/unsaturated) and (cis/trans)
unsaturated, trans
trans/saturated: oil or fat at room temp?
fat
Micelle structure
polar heads out, ONE TAIL in - thermodynamically stable form
smallest fatty acid
acetic acid
fatty acids
Fatty acids are chains of hydrogen-bearing carbon atoms that have a carboxylic acid at one end and a methyl group at the other end.
draw a glycerol
draw a fatty acid
Fatty acid carbon atoms are usually numbered beginning with the ___ terminal carbon atom.
carboxy
triacylglycerol
aka a triglyceride- a glycerol backbone + fatty acid- THIS IS A FAT
are fats and oils polar/nonpolar molecules?
mostly nonpolar
how does chain length influence a fatty acid’s properties?
Short chain length and the presence of cis double bonds enhances the fluidity of fatty acids. (less opportunities to form van der waals forces with its own chain)
Cis ____fatty acids are essential components of our diets because humans have little ability to synthesize double bonds distal
polyunsaturated
_____ are energy rich. Because they are hydrophobic and reduced, a gram of anhydrous fat stores more than six times the energy of a gram of hydrated glycogen.
Triacylglycerols
where are triacylglycerols normally stored?
adipose (fat) tissue
The three common types of membrane lipids are:
- Phospholipids
- Glycolipids
- Cholesterol
phosphoglycerides
type of phospholipid that is bound to a glycerol backbone. theres a phosphate group within the fatty acid chain.has a phosphate group attached to the O of the glycerol. Also attacheed to a small organic molecule
this is the umbrella group containing phosphatidylcholine, etc
Phospholipids are composed of four components:
fatty acids (usually 2), a platform/backhone, a phosphate, and an alcohol (small molecule on end). Two common platforms are glycerol and sphingosine
Phospholipids with a glycerol platform are called
phosphoglycerides
whats the major class of membrane lipids
phospholipids
sphingolipids
phospholipids with a sphingosine backbone instead of glycerol
what’s different about Archea phospholipids
Archea phospholipids have ether linkages instead of ester linkage of acyl chains. The ether linkages and branching structure of membrane lipids of extremophiles prevent hydrolysis and oxidation of membranes in harsh environments.
t/f: membrane lipids can include carbohydrates
true
what are glycolipids and what do they do
Glycolipids are carbohydrate-containing lipids.
The carbohydrate components of glycolipids are on the extracellular surface of the cell membrane, where they play a role in cell-cell recognition.
give an example (the simplest form) of a glycolipid
Cerebrosides are the simplest glycolipids with one sugar attached to sphingosine.
what are gangliosides
a type of glycolipid, isolated from the brain- complex sugar chains. in taysachs, lack enzyme to degrade these.
what are membrane anchors
Membrane anchors are hydrophobic groups that are covalently attached to proteins (in blue) and tether the proteins to the membrane
structure of steroids
3 hexagons + 1 pentagon
is cholesterol polar or nonpolar?
OH group makes it a little polar. Whole thing is amphipathic.
name the functions of cholesterol
1) need it to make hormones ,
2) make bile, and
3) be a major component in cell membranes , adding to fluidity (tails cant pack as well with cholesterol stuck in there) and stability
Subunit structure of glycolipids
more protein than sugar.
lipids with a carbohydrate attached by a glycosidic bond.
acyl group
fatty acid
how do you modify steroids to make different things
Different functional groups (e.g., -OH, -CH3, =O) hang off the rings, creating different molecules (e.g., cholesterol, cortisone, estrogen, progesterone, testosterone, bile acid)
