MOLECULAR NUTRITION LIPID PRACTICAL

what are lipids

macromolecule soluble in non-polar solvents and insoluble in water

includes fatty acids, waxes, sterols, fat-soluble vitamins ADEK

functions of lipids

energy storage, cell structure, and cell signaling

how is acylglycerol formed

in condensation reactions between OH groups of glycerol and COOH groups of fatty acids

what are fatty acids

carboxylic acids with long chain hydrocarbon tails

where do the predominant fatty acid residues reside in higher animals and plants

16-18 carbons

are fatty acids hydrophobic or hydrophillic

hydrophobic

what does the non polar hydrocarbon chain confer to fatty acids

hydrophobicity

what are the three different classifications of fatty acids

saturated: all single carbon bonds

unsaturated: one or more double bonds in hydrocarbon tail

mono→one double bond

poly→more than one

how is mono palmitin formed

one of the three alcohol groups on glycerol and one molecules of palmitic acid

do plant lipids or animal lipids have lower melting points

plant lipids→tend to be unsaturated and therefore are liquid at room temperature

what are the main acids in olive oil versus sunflower oil

olive oil is mainly oleic acid and sunflower oil is mainly linoleic acid

what differentiates phospholipids from fatty acids

they have a phosphate group and are amphipathic

name the two types of phospholipids

glycerophospholipids: 2 fatty acid groups with 3 position on glycerol occupied by phosphate group attached to alcohol

Sphingolipids: glycerol is replaced with sphingosine

phosphate head versus fatty acid tail in phospholipids

phosphate head is negatively charged and contains polar groups therefore is hydrophilic

fatty acid tail is nonpolar and therefore hydrophobic

what is the most abundant phospholipid in animals and plants

phosphocholine→builds membrane bilayers

where is phosphatidylserine found

in myelin in brain tissue and egg yolk

what is the structure of cholesterol

tetracyclic ring system

purpose of cholesterol

in eukaryotic cells, it is a major component of the cell membrane and it has a roll in maintaining cell fluidity and it is a precursor for steroid hormones, bile salts, and vitamin D

what does chromatography do

separates individual components of a mixture based on characteristics differences in size charge or polarity

what are the three components of chromatography

stationary phase, chromatographic bed, and mobile phase

components of TLC

stationary phase=absorbant such as silica;

chromatographic bed=thin layer of the stationary phase spread onto glass or plastic plate;

mobile phase=liquid(organic solvent) moving up the plate via capillary action

what happens if the molecule is more polar in TLC

is it more strongly absorbed by the silica therefore will NOT move up the plate

what does iodine stain

unsaturated fatty acids→brown spots→almond and olive oil

fluorescein spary

stains all lipids giving a fluorescent light under UV→monopalmitin did not move up plate→most bind to silica

ninhydrin spray

binds to amino groups and gives purple spots when heated

molybdenum blue

binds to phospholipids and gives blue spots

what are fatty acids stored as

triglycerides

is there cholesterol in the mitochondrial inner membrane

NO, there is cardiolipin instead

is silica polar or nonpolar

polar so it acts as stationary phase

do more polar molecules move farther up or less far up the TLC plate

less far since they bind to silica

what can be used for most lipid detection

fluorescein and light

is mono or tri palmitin most polar and why

mono is most polar because it moved the least amount up the plate due to it having the least fatty acid tails

what is this lipid and what is its function

cholesterol→ major component of the cell membrane and it has a roll in maintaining cell fluidity and it is a precursor for steroid hormones, bile salts, and vitamin D

what is this lipid and what is its function

free fatty acid→energy source

what is this lipid and what is its function

triglyceride→energy storage

what is this lipid and what is its function

phospholipid→cell membrane phospholipid bilayer; hydrophilic phosphate head with hydrophobic fatty acid tail

is this lipid saturated or unsaturated and why

unsaturated because it has a double bond

is cholesterol more polar or nonpolar

more nonpolar except for the hydroxyl group attached the first ring

which of these is an ester

structure E→ C-O-C

is silica polar or non polar

polar

Why does ninhydrin not detect phosphatidylcholine

Ninhydrin does not detect phosphatidylcholine because ninhydrin specifically reacts with free amino groups (-NH₂), and phosphatidylcholine is a phospholipid