Lipids Flashcards
Lipids are not defined by chemical structure, they are instead defined by their common chemical property, which is…
hydrophobicity
What is the energy storage form of lipids
triglycerides
What is the structural element of biological membranes in terms of lipids
phospholipids
What is the lipid type involved in signal transduction
hormones
What are glycolipids
lipids + carbs
What are lipoproteins
lipids + protein
What is an example of glycolipids in the human body
blood groups (glycolipids displayed on the outer surfaces of blood cells)
What is an example of lipoproteins in the human body
VLDL, LDL, HDL, etc.
What is the simplest form of lipid being discussed
fatty acids
What functional group is found on the ends of lipids
carboxyl
A fatty acid with all single bonds is
saturated
A fatty acid with one or more double bonds is
unsaturated
In the delta system, how are fatty acids named
the number of carbons followed by number of double bonds separated by a colon (ie. 18:2)
- the position of these double bonds is specified by superscript numbers in brackets
In the omega system, how are fatty acids named
using the omega symbol, the fatty acid is specified by the location of the first double bond starting from the omega carbon (the end opposite to carboxyl)
What is carbon 1 of a fatty acid
the carbon in the carboxyl group
What are the 3 important characteristics of commonly occurring fatty acids in the body
unbranched
evenly numbered carbons
double bonds in cis
When is a kink in a fatty acid chain observed
in a cis configured double bond
What is the commonly occurring fatty acid with 12 carbons
laurate
What is the commonly occurring fatty acid with 14 carbons
myristate
What is the commonly occurring fatty acid with 16 carbons
palmitate
What is the commonly occurring fatty acid with 18 carbons
stearate
What is the commonly occurring fatty acid with 20 carbons
arachidate
What is the mneumonic to help remember the commonly occurring fatty acids
let my pal stay around
What is the process by which trans fats are manufactured
partial hydrogenation
What is the conformation change seen in trans fats
allows fatty acid to adopt an extended conformation (not kinked like cis)
In appearance, trans fats resemble…
saturated fats
As chain length increases, melting point…
increases (need higher temp)
As chain length increases, solubility…
decreases (more hydrophobicity)
Since unsaturated fatty acids pack less regularly due to the double bonds, what is the impact on melting temp
melting temp decreased (takes less temp to break interactions)
In trans fatty acids, since they mimic the conformation of saturated fats, what is seen in melting temp
increased (packs more regularly due to lack of kinks, therefore harder to break apart)
Between (18:0), (16:0), (18:1), and (18:2) fatty acids, which will have the highest melting temp
(18:0) because it has the longest length and fewest double bonds so it is tightly packed and higher heat is required to break the bonds
When carboxylic acids combine with alcohols, ___________ are formed
esters
What carboxylic acids are combined with acids, _______________ are formed
anhydrides
Triglycerides are formed by linking three fatty acids to a __________________ through ____________ linkages
glycerol; ester linkages
What is the chemical nature of triglycerides (think in terms of water)
very hydrophobic
What is a simple triglyceride
all three fatty acids are the same
What is a complex triglyceride
three fatty acids are not all the same (2 or 3 different)
The mixture of H2PO4- and HPO4^2- is represented by the notation…
Pi
Phosphoric acid (H3PO4) is a triprotic acid that exists as an equilibrium mixture of _______________ and ______________ at pH 7
H2PO4- and HPO4^2-
Phosphorylation adds ________________ charges to molecules
negative
By adding negative charges via phosphorylation, what occurs
increased water solubility
Phosphoric acid + alcohol =
phosphate ester
Phosphoric acid + acid =
phosphoanhydride
What is the conformation of phosphoglycerides
glycerol backbone, 2 fatty acids, and a phosphate group on the third glycerol head attached by a phosphodiester bond
What does it mean to be amphipathic
hydrophobic and hydrophilic
How are phosphoglycerides amphipathic (think about lipid bilayers)
hydrophilic head, hydrophobic tail
What are some major classes of glycerophospholipids
phosphatidylcholine (PC)
phosphatidylethanolamine (PE)
phosphatidylserine (PS)
phosphatidylglycerol (PG)
What is the major head group in phosphatidylcholine (PC)
choline
What is the major head group in phosphatidylethanolamine (PE)
ethanolamine
What is the major head group in phosphatidylserine (PS)
serine
What is the major head group in phosphatidylglycerol (PG)
glycerol
Which of the glycerophospholipids are the major constituents of most membranes
PC and PE
Are the previously listed glycerophospholipids one singular molecule or each a class of molecules
classes (different fatty acids on the R1 and R2 locations create variations in the potential molecules)
If only one layer is present, what formation does it take on
micelle (folds into a circular single layer formation)
If two layers are present, what formation do they take on
bilayer
If many bilayers are folded into a circular shape and brought together, what is the name of this formation
vesicle (liposomes)
What is the fundamental structure of the cell membrane
lipid bilayer
In the analysis of lipids, how can they be separated based on polarity
column chromatography or thin layer chromatography
What is the most important type of chromatography used for fatty acid separation
gas-liquid chromatography
- mobile phase is a gas
- fatty acids are separated based on chain length/degree of saturation
How can isolated fatty acids in chromatography experiment be identified
through mass spectrometry
The pattern of double bonds in the polyunsaturated fatty acids that are commonly found in mammalian membrane lipids is best represented as…
-CH2-CH=CH-CH2-CH2-CH=CH-
