Lipids Flashcards
Fatty acids
long hydrocarbon chain of various lengths (12-24) and degree of saturation of terminated with carboxylic acid group.
Increasing chain length..
decrease solubility
Palmitic Acid/ Palmitate
16 C
hexadecanoic Acid
Linoleic Acid/ Linoleate
18:2 cis 9, cis 12
cis, cis-9,12-octadecadienoic acid
Milk contains
fatty acids with 4-10 carbons
capric acid/ caprate
10:0
lauric acid/ laurate
12:0
Palmitoleic acid/ palmitoleate
16:1 cis 9
stearic acid/ sterate
18:0
palmitic acid is the precursor of other fatty acids (except essential fatty acids)
Structural lipids and triacylglycerol contain fatty acids with at least 16 carbons
oleic acid/ oleate
18: 1 cis 9
linoleic acid/linoleate
18:2 cis, cis 9,12 cis, cis-9,12-octadecadienoic acid -precursor of arachidonic acid -deficiency leads to making arachidonic acid essential essential -w 6 fatty acids
alpha linolenic acid/ linoleate
18:3 cis, cis, cis 9,12,15
essential
-precursor of other w 3 fatty acids
-deficiency leads to decreased vision and learning behaviors
arachidonic acid/ arachidonate
20:4, cis, cis, cis, cis 5,8,11,14
precursor to prostoglandins
lignoceric acid/ lignocerate
24:0
nervonic acid/ nervonate
24:1 cis 15
What is the function of lipids
cell membranes
- energy storage
- cell signaling
Phospholipids
glycerol
polar head group
-two nonpolar tail groups
sphingomylin
nonglycerol containing phospholipid
-contains spigosine (modified serine_
Glycolipids
substitued serine
- 2 catty acids
- carbohydrate (glucose)
triacylglycerol
glycerol
three fatty acids
- accumulates as fat droplets in cytoplasm
cholesterol
precursor to steroid hormones,
-27 carbons
4 rings (A,B,C,D called steroid nucleus)
-substituted perhydrocyclopentanopenanthrene
Micelle
formed by ionized fatty acids. steric constraints precent formation by phospholipids and glycolipids, which preferntially form vesicles
phospholipid bilayers contain
phospholipids, glycolipids and cholesterol
Energy consideration formation
hydrophobic interactions between fatty acid tails
-electrostatic and hydrogen bond between head group and water molecules
transmembrane protein
protein passes through both layers of the bilayer
-extraction requires detergent or organic solvent
Peripheral
attached to one side of membrane
- associated with polar head groups.
- extraction requires increase in ionic strength or change in pH
Bacteriorhodopsin
archaeal protein
- uses light energy to transport protons out of the cell to create protein gradient
- seven alpha helixes span membrane
glycophorin
red blood cell membrane protein
-single alpha helix spans membrane
hydrophobic alpha helixes can be identified by plotting
hydropathy index
-plot sliding 20 amino acid average of free energy change when a helical segment moves from interior of membrane to water
Plotting hydrophathy is not able to detect
beta barrels
Porin
E.coli and Rhodobacter capsulatus
-allows movement of material across the membrane
Membrane fluidity is controlled by
fatty acid composition and cholesterol content
- fatty acids exist rigid state or fluid state
- change of state occurs abruptly at Tm:
- length of fatty acid
- degree of saturation
lower Tm
shorter fatty acids
more double bonds
cholesterol
membrane antifreeze and coolant
