lipids 1 Flashcards
describe lipids?
they are all insoluble in water and soluble in organic solvents
what are the functions of lipids?
structural components of membranes
energy reserves, mainly in the form of triacylglycerols
lipids and lipid derivatives serve as vitamins and hormones
what are the 7 types of lipids?
fatty acids
fats and oils (triacylglycerols)
phospholipids
glycolipids
prostaglandins
terpenes (a.k.a isoprenoids)
steroids
why are fatty acids important?
they are essential components of other lipids
describe fatty acids?
contain a long hydrocarbon chain (non-polar end) and a terminal carboxylic acid group (polar end)
numbering of the carbon in an fatty acids starts where?
carboxylic acid group end
at physiological pH the fatty acid is what?
the carboxyl groups of fatty acids are readily ionized
this makes fatty acids negatively charged (COO-)
how many carbons do most fatty acids contain?
12 to 20 carbon atoms
what is a saturated fatty acid?
contain no carbon-carbon double bonds
12:0 what does the 12 represent?
12 carbons and 0 double bonds
name another saturated fatty acid?
palmitic acid
what is an unsaturated fatty acid?
contain at least one carbon-carbon double bond
what us a monosaturated fatty acid?
fatty acids have 1 C=C bond,
what is a polyunsaturated fatty acid?
fatty acids have 2 or more C=C bonds
where are cis double bonds found?
unsaturated fatty acids
how are most fatty acids made?
precursor molecules in the body (non-essential fatty acids)
what are the 2 essetnail fatty acids?
linoleic acid
linolenic acid
can linolenic acid and and linolec be synthesized from precursors?
no
what can linoleic and linolenic aicds be found?
obtained in the diet found in fish, shellfish,etc
what are omega 3 fatty acids?
unsaturated fatty acids in which the double bond closest to the methyl (omega) carbon occurs at the third carbon in from that end
what can omega 3 inhibit?
platelet aggregation
increase the ratio of high-density to low-density lipoproteins while lowering overall plasma lipid levels
they may inhibit some cancers
what is shortest omega 3 fatty acid called?
linolenic
what are omega 6 fatty acids?
unsaturated fatty acids in which the double bond closest to the methyl (omega) carbon occurs at the sixth carbon in from that end
diets in which the ratio of omega 6 to omega 3 fatty acids is high has linked to what>
been linked to promotion of some cancers
what is the shortest omega 6 fatty acid?
linoleic
what does the chain length affect>
affects the melting point of fatty acids
the longer the fatty acid, the higher the melting point
shorter fatty acids are more fluid than longer ones
how does saturatio effect a fatty acid?
affects the melting point
more saturated the fatty acid, the higher the melting point
an unsaturated fatty acid is more fluid than a saturated one of similar size
longer chains that are more saturated are what?
likely to be solid at room temperature
they can pack more closely together to form a solid structure than shorter or unsaturated chains
why are fats and oils essential?
fats carry essential vitamins = A D E and K
provide our most concentrated form of dietary energy
why are fats and oil important?
They are the precursors from which we synthesize our own fat
They are the precursors from which we synthesize our own fat
how is fat stored?
adipose tissue
what is adipose tissue made from?
made up of specialised cells called adipocytes, which contain globules of stored lipid
how are triacylglycerols formed?
3 fatty acids + 1 molecule of glycerol
link together to form
1 triacylglycerol molecule + 3 water molecules
fats are
TAGs that are solid at RT
oils are
TAGs that are liquid at RT
TAGs found in animals tend to contain?
saturatedhydrocarbon chains (animal fats - like lard, butter)
TAGs found in plants tend to contain
unsaturatedhydrocarbon chains (oils - like olive oil, palm oil)
how can lipids be transported around the body?
as fatty acids, but are stored in adipocytes as TAGs
how can TAGS be hydrogenated?
if they contain unsaturated fatty acids
can tags be broken down to their glycerol and fatty acid components
boil with acid or alkali
- superheated steam
- lipases
what is RANCIDITY
development of undesirable odors and flavors in fats and oils when they undergo oxidation.
what is a soap?
soap is the combination of a fatty acid with a metal
what is the most commaest soaps?
sodium or potassium salts of fatty acids
how are soaps made?
made by the hydrolysis (saponification) of oils or fats
what are the steps to produce soap?
heat oil or fat with dilute NaOH
when hydrolysis is complete, get rid of excess glycerol and alkali by boiling with large amounts of water
precipitate soap by the addition of NaCl
dry, add perfume, colour, etc
how do soaps work?
soaps are amphiphilic molecules
they have an ionic polar end (hydrophilic)
and a non-polar hydrocarbon chain (lipophilic
because grime and dirt are often hydrophobic, they associate with the lipophilic ends of the soap molecules
how do soap molecules arrange themselves when faced with dirt>
molecules arrange themselves into micelles & dirt is incorporated into the interior of these micelles
what happens when the miccles are immersed in the dirt?
this means it is emulsified (solubilised) in aqueous solution) and thus can becleaned away
