- WELCOME TO LIPIDS PART ONE.
IN THIS TUTORIAL WE'LL LOOK AT FATTY ACIDS AND THEN FATS
AND OILS ALSO KNOWN AS TRIGLYCERIDES.
LET'S GET STARTED.
ALL RIGHTY. SO WE HAVE TALKED ABOUT FATTY ACIDS BEFORE,
BUT LET'S DO A BRIEF REVIEW.
SO PALMITIC ACID, HERE IS THE CONDENSED FORMULA
FOR PALMITIC ACID.
SO LET'S GO AHEAD AND WRITE OUT
THE SKELETAL LINE STRUCTURE.
SO WE CAN SEE THAT IT HAS A 16 CARBON CHAIN, RIGHT?
THE CARBOXYLIC ACID CARBON, THE 14 METHYLENE GROUPS,
AND THE TERMINAL CARBON.
SO THERE WE GO. AND SO THIS IS REALLY JUST A CARBOXYLIC ACID
BUT WE CALL THEM FATTY ACIDS
BECAUSE THERE'S A LONG HYDROPHOBIC TAIL, RIGHT,
THAT WANTS LONDON FORCES.
SO THIS PART OF THE MOLECULE LOVES TO BE WITH OTHER FATS.
OF COURSE, THE CARBOXYLIC ACID PART IS POLAR
AND WANTS TO BE WITH WATER.
BUT THIS LONG HYDROCARBON TAIL WINS.
SO THIS WOULD NOT BE SOLUBLE IN WATER.
THIS WOULD BE FAT SOLUBLE.
OKAY. SO WE--SINCE WE STUDIED
THIS BEFORE WE GOT KIND OF WARMED UP THERE A LITTLE.
HERE ARE FOUR DIFFERENT FATTY ACIDS, AND SO FATTY ACIDS
ARE DESCRIBED, RIGHT, BASED OFF OF THE HYDROCARBON TAIL.
SO THIS IS HOW WE DISTINGUISH BETWEEN FATTY ACIDS.
SO LET'S PRACTICE MAKING THAT DISTINCTION.
SO ONE OF THESE FATTY ACIDS IS SATURATED,
ANOTHER ONE IS UNSATURATED,
AND ONE OF THEM IS POLYUNSATURATED.
AND FOR THE UNSATURATED,
WE CAN GO AHEAD AND MAKE A FURTHER DISTINCTION,
DOES IT HAVE CIS OR TRANS CARBON-CARBON DOUBLE BONDS.
ALL RIGHTY, SO TAKE A MOMENT TO DESCRIBE THESE FATTY ACIDS
AND THEN WE'LL COMPARE ANSWERS.
ALL RIGHTY, SO HERE, WE CAN SEE STEARIC ACID IS SIMILAR
TO PALMITIC THAT IT'S A SATURATED FAT
BECAUSE THE HYDROCARBON TAIL HAS THE MAXIMUM NUMBER
OF HYDROGENS.
AND THEN WHEN WE LOOK AT OLEIC ACID
WHICH IS FOUND IN OLIVE OIL,
WE SEE THAT THERE'S A DOUBLE BOND PRESENT
AND HERE IS ELAIDIC ACID,
THERE'S ALSO A DOUBLE BOND PRESENT.
SO WHEN WE LOOK AT THESE TWO FATTY ACIDS,
WE WOULD SAY THEY'RE UNSATURATED BECAUSE WE LOST,
RIGHT, WE LOST SOME HYDROGENS TO FORM THE DOUBLE BONDS.
SO NOW, WE CAN FURTHER DISTINGUISH
BETWEEN THE UNSATURATED FATTY ACIDS HERE.
WE WOULD SEE A CIS DOUBLE BOND
AND HERE WE WOULD SEE A TRANS DOUBLE BOND, RIGHT?
AND SO THEN WE WANT TO KEEP IN MIND THAT IN MOTHER NATURE
WE ONLY FIND CIS DOUBLE BONDS AND THAT TRANS DOUBLE BOND,
RIGHT, ARE MANMADE. OKAY.
AND THEN FOR THIS LAST FAST FATTY ACID HERE,
NOW WE SEE THAT WE HAVE MORE THAN ONE DOUBLE BOND.
SO WE WOULD DESCRIBE THIS AS POLYUNSATURATED. OKAY.
AND THERE'S LINOLENIC ACID. ALL RIGHTY.
NOW LET'S ARRANGE THE FATTY ACIDS
IN ORDER OF DECREASING MELTING POINT.
SO WE'LL START WITH THE HIGHEST MELTING POINT
THEN WE'LL GO TO THE LOWEST MELTING POINT.
AND SO REMEMBER THAT THE HIGHEST MELTING POINT, RIGHT,
THAT'S GOING TO BE A SOLID AT ROOM TEMPERATURE
AND SO IT'S GOING TO HAVE, RIGHT, THE STRONGEST IMF'S,
INTERMOLECULAR INTERACTIONS.
SO IF WE LOOK--OOP, EXCUSE ME.
OKAY, SO IF WE LOOK AT THIS, RIGHT,
SO WE WANT TO ARRANGE FROM THE HIGHEST MELTING POINT
WHICH MEANS MOST LIKELY THAT IT'S A SOLID
AT ROOM TEMPERATURE, THE LOWEST MELTING POINT, RIGHT,
IT MELTS REALLY EASY.
SO THESE ARE OFTEN GOING TO BE LIQUIDS AT ROOM TEMPERATURE.
AND IF YOU'RE WONDERING WHAT IN THE WORLD
IS ROOM TEMPERATURE, IT DEPENDS ON WHO YOU ASK,
ABOUT 20 DEGREES C.
ALL RIGHTY, SO REMEMBER THAT IT'S ALL ABOUT--
AT THIS POINT WE HAVE--WE--
EACH OF THE MOLECULES HAS ONE CARBOXYLIC ACID GROUP.
SO THAT'S NOT GOING TO BE A DIFFERENCE.
SO THE DIFFERENCE IS GOING
TO COME FROM THE HYDROCARBON TAILS.
SO IF WE LOOK AT THE HYDROCARBON TAILS,
WE SEE THAT THE SATURATED MAKES A PERFECTLY
STRAIGHT CHAIN.
SO WE WOULD BE ABLE TO STACK
ONE FATTY ACID NEXT TO THE OTHER
AND WE WOULD HAVE A HUGE OVERLAP OF SURFACE AREA
FOR INTERACTIONS.
SO THE SATURATED FAT OR THE SATURATED FATTY ACID
WOULD HAVE THE HIGHEST MELTING POINT.
AND THAT WOULD--SO THAT WOULD BE--WE COULD ALSO JUST USE
THE LETTERS, SO THAT WOULD BE A.
SO THAT IS GOING TO MELT HIGHER,
SO NOW LET'S LOOK AROUND.
SO USING THAT LOGIC WE CAN SEE THAT THE TRANS,
THE KINK IN THE TRANS IS MUCH SMALLER
THAN THE KINKS IN THE CIS.
AND SO WITH EACH KINK WE ARE GOING TO DISRUPT
THE INTERACTION BETWEEN TWO FATTY ACIDS.
AS WE HAVE LESS SURFACE AREA,
WE ARE GOING TO WEAKEN OUR INTERMOLECULAR FORCES.
SO NEXT WOULD COME C, THE TRANS FAT.
AND THEN QUITE LOGICALLY,
WE COULD SEE THAT THE MORE KINKS THE LESS INTERACTION
WE'LL GET BETWEEN FATTY ACIDS.
SO NEXT WOULD COME B AND LAST WOULD BE D.
ALL RIGHT, SO THIS WAS ALL DETERMINED
FROM THE STRUCTURE OF THE FATTY ACID TAIL.
OKAY, ONE LAST THING TO LOOK AT
IS WITH OUR UNSATURATED FATTY ACIDS
WE HAVE LEARNED TWO SYSTEMS FOR NAMING THEM
OR CLASSIFYING THEM.
AND SO THE FIRST ONE WAS-- IS THE OMEGA SYSTEM.
AND IT'S INTERESTING WE HAVE TWO DIFFERENT SYMBOLS
THERE THAT WE COULD USE.
AND REMEMBER WITH THE OMEGA SYSTEM
THAT WE COUNT FROM THE END OF THE FATTY ACID TAIL.
SO IF WE WANTED TO DO THE OMEGA SYSTEM HERE,
WE START HERE AND WE WOULD SAY "AH, THIS IS AN OMEGA-6."
ALL RIGHT, SO WE GOT THERE OMEGA-6.
NOW THERE'S THE DELTA SYSTEM, RIGHT?
SO WITH THE DELTA SYSTEM, RIGHT, SO THAT GIVES
THE TRIANGLE FOR DELTA.
NOW THIS IS SIMILAR TO IUPAC NOMENCLATURE,
LIKE IF WE WERE GOING TO NAME IT,
WE COUNT FROM THE CARBOXYLIC ACID CARBON.
ALL RIGHT. SO-- AND THE INTERESTING THING
ABOUT THE DELTA IS WE INCLUDE ALL DOUBLE BONDS.
ALL RIGHT, WITH THE OMEGA SYSTEM,
WE JUST LET EVERYBODY KNOW
WHERE THE FIRST DOUBLE BOND APPEARS, BUT WITH THE DELTA,
RIGHT, SO NOW WE'RE GOING TO COUNT
FROM THE CARBOXYLIC ACID,
SO WE WOULD SAY THAT THIS IS DELTA 9, 12.
ALL RIGHT? SO THE LOCATION OF THE DOUBLE BONDS IS A RIGHT--
A RIGHT SUPERSCRIPT. RIGHT?
AND WE WOULD SHOW ALL CARBON-CARBON DOUBLE BONDS.
SO THEY'RE COMPARING AND CONTRASTING, RIGHT?
SO OMEGA STARTS AT THE END OF THE CARBON CHAIN
AND WE JUST GIVE THE LOCATION OF THE FIRST DOUBLE BOND.
DELTA ON THE OTHER HAND, WE START FROM THE CARBOXYLIC ACID
AND THEN WE TELL EVERYBODY
WHERE ALL OF THE DOUBLE BONDS ARE.
SO THERE'S A BRIEF REVIEW OF FATTY ACIDS
AND NOW WE WILL LOOK MORE CLOSELY AT FATS AND OILS
BUT FATTY ACIDS ARE A MAJOR COMPONENT OF FATS AND OILS.
SO IT'S A GREAT PLACE TO START.
ALL RIGHTY, SO LET'S GO TO THE NEXT PAGE.
ALL RIGHTY. SO WE'VE BEEN LOOKING AT--WELL, LET'S SEE.
SO LET'S BOX THE GLYCERIN BACKBONE
AND CIRCLE THE ESTER GROUPS
AND THEN TAKE OUR KNOWLEDGE OF FATTY ACIDS
AND USE IT TO EXPLAIN HOW THE R-GROUPS
WOULD AFFECT THE PHYSICAL STATE OF THE TRIGLYCERIDES.
AND JUST LINGUISTICALLY BEFORE WE GET TOO FAR, RIGHT,
SO FATS IMPLY THAT THEY COME FROM ANIMALS,
OILS FROM PLANTS, RIGHT, BUT THEN CHEMICALLY
WE DON'T REALLY CARE ABOUT THE ORIGINS
WHEN WE THINK ABOUT IT.
WE JUST CALL IT A TRIGLYCERIDE
BECAUSE OF THIS GLYCERIN BACKBONE.
THEY ALSO GET CALLED TRIACYLGLYCERIDES
AND THEY CAN GET ABBREVIATED AS A TAG, SO LOTS OF SYNONYMS.
ALL RIGHTY. SO LET'S BOX THE GLYCERIN BACKBONE,
AND SO THIS IS OUR GLYCERIN BACKBONE, RIGHT,
SO IT'S JUST A TRIAL,
RIGHT, AT THREE ALCOHOLS ALL TOGETHER.
AND THEN WE'LL CIRCLE THE ESTER GROUP.
SO THEN HERE WOULD BE THE ESTER GROUPS RIGHT THERE.
AND THEN AS WE JUST SAW FROM OUR FATTY ACID REVIEW, RIGHT,
THAT SATURATED AND TRANS ARE GROUPS, RIGHT,
TIGHTLY PACKED TO FORM SOLIDS AT ROOM TEMPERATURE.
AND THAT WHEN WE HAVE THE CIS DOUBLE BONDS, CIS ARE GROUPS,
HAVE BENDS, RIGHT THAT WEAKEN THE INTERACTIONS AND SO THAT,
RIGHT, THAT FOR--INTEND TO FORM LIQUIDS
AT ROOM TEMPERATURE.
OKAY, SO THERE'S THE OVERALL STRUCTURE.
SO, BASICALLY IT'S JUST THREE ESTERS, RIGHT.
AND THE MAIN REACTIONS THAT TRIGLYCERIDES CAN OCCUR
ARE REDUCTION OR HYDROGENATION,
WHICH IS THE SOURCE OF TRANS FATS.
OXIDATION, IF YOU'VE EVER SMELLED RANCID BUTTER, RIGHT,
RANCIDITY, AND THEN HYDROLYSIS
WHICH WE CAN USE FOR CATABOLISM
OR TO MAKE SOAP, SAPONIFICATION.
SO WE HAVE A FAT MOLECULE HERE, CAN BARELY FIT IT.
AND THEN YOU CAN LOOK AND YOU SHOULD BE ABLE TO CLASSIFY
AND RECOGNIZE WHICH REACTION IS RICH.
SO, I'LL GIVE YOU A MOMENT TO DO THAT.
ALL RIGHTY, RIGHT.
SO IN THIS FIRST REACTION WE NOTICE,
AH, WE HAVE AN ADDITION OF OXYGEN.
SO, THIS IS CLEARLY AN OXIDATION REACTION, RIGHT,
THAT LEADS TO RANCIDITY.
WHEN WE LOOK AT THE SECOND REACTION, WE NOTICE, HUH,
EVERYTHING WAS ALL BENT HERE,
WE HAD A BUNCH OF CIS DOUBLE BONDS,
AND WHAT HAPPENED RIGHT, WE LOST SOME OF OUR DOUBLE BONDS,
AND THEN WE ENDED UP WITH A TRANS DOUBLE BOND.
SO, THIS WOULD BE OUR REDUCTION.
SO WHEN WE TALK ABOUT--RIGHT,
SO THIS WOULD BE FOR AN EXAMPLE A,
HYDROGENATED OIL. RIGHT?
SO WE WOULD--WITH ALL OF THE CIS BONDS HERE,
THIS IS PROBABLY AN OIL.
RIGHT?
IT'S GOING TO BE A LIQUID AT ROOM TEMPERATURE,
AND SO THEN THE PROCESSED FOOD INDUSTRY DOES THE REDUCTION
TO MAKE THE HYDROGENATED OILS.
THERE'S SEVERAL REASONS WHY THEY DO THIS.
ONE, IS BECAUSE NOW, IF WE LOOK AT THIS HYDROGENATED OIL
WOULD WE EXPECT IT TO BE A LIQUID OR A SOLID?
NOTICE THAT NOW IT IS MOST LIKELY A SOLID, RIGHT?
AND HERE WE WOULD EXPECT IT TO BE A LIQUID.
SO HYDROGENATED OILS ARE REALLY GREAT
FOR THE PROCESSED FOOD INDUSTRY BECAUSE WE GO
FROM A LIQUID TO A SOLID,
AND SOLIDS ARE MUCH EASIER TO TAKE--KEEP--CARE OFF BECAUSE
IF YOU SPILL THEM THEY DON'T MAKE SUCH A BIG MESS.
ANOTHER ADVANTAGE FOR THE PROCESSED FOOD INDUSTRY
IS THAT MOLDS DON'T LIKE TO EAT HYDROGENATED OILS
AND SO THEY BECOME RANCID SLOWER.
HOWEVER, THESE BENEFITS TO A PROCESSED FOOD
ARE NOT BENEFITS FOR US.
MY OWN PERSONAL RULE OF THEM IS IF IT'S NOT GOOD ENOUGH
FOR MOLD, IT'S NOT GOOD ENOUGH FOR ME.
AND WHAT WE'RE GOING TO LEARN IS IN THIS CHAPTER IS THAT
THE FATTY ACIDS AND LIPIDS ARE IMPORTANT
TO OUR CELL MEMBRANES,
AND OUR CELL MEMBRANES ARE VERY IMPORTANT
TO OUR OVERALL HEALTH.
OUR CELL MEMBRANES ARE THE GATEKEEPERS OF OUR CELL,
LETTING IN AND OUT NUTRIENTS AND WASTE.
AND SO IT'S VERY DISCONCERTING TO THINK ABOUT HAVING CHANGES
IN THE BASIC STRUCTURE OF THE BUILDING BLOCKS
FOR OUR CELL MEMBRANES.
AND THAT IS WHY NOW TRANS FATS ARE NO LONGER ALLOWED IN FOOD
AND THERE MUST BE LABELS FOR THEM
BECAUSE OF THESE HEALTH CONCERNS.
AND THEN LAST BUT NOT LEAST, LET'S LOOK AT THE HYDROLYSIS.
SO, HERE WE WOULD HAVE SOME KIND OF LIPASE
AND OF COURSE WE WOULD NEED WATER.
AND THEN WE CAN LOOK IN HERE AND BY NOW WE'RE EXPERTS,
WE FIND THE CARBONYL CARBON
AND WE KNOW THE WATER WILL COME IN,
AND HYDROLYZE EACH OF THE ESTER BONDS,
AND SO THEN WE CAN SEE THAT THESE HYDROGENS
CAME FROM THE WATER,
AND THESE HYDROXYL GROUPS CAME FROM THE WATER,
AND SO WE HAVE BASICALLY A SIMPLE ESTER HYDROLYSIS.
THE ONLY TRICK IS THAT WE NEED THREE WATER MOLECULES
BECAUSE THERE ARE THREE ESTER GROUPS.
ALL RIGHT, OKAY, SO, WE'VE GONE THROUGH
THE BASIC STRUCTURE OF FATS AND OILS,
AND THE THREE MAIN REACTIONS THAT THEY UNDERGO.
AND SO NOW JUST DO A LITTLE BIT OF CONNECTION
TO OUR FUNCTIONAL GROUP REACTIONS TO HELP BRIDGE
WHAT WE LEARNED IN VERY SIMPLE ORGANIC MOLECULES
A FEW WEEKS AGO AND NOW,
WHAT WE'RE APPLYING TO THESE MORE COMPLICATED
BIOCHEMICAL MOLECULES, RIGHT?
SO LET'S LOOK AT THESE THREE REACTIONS, THE ESTER,
THE THIOESTER, AND THE AMIDE, EACH REACTING WITH WATER.
AND NOTICE WHAT RESULTS, CARBOXYLIC ACIDS,
AND THEN WE--REMEMBER WE WERE CALLING THIS DISEASE, RIGHT,
THE ALCOHOL, THE THIOL, OR THE AMINE.
SO WHAT REACTION IS SHOWN?
IT'S THE SAME CLASSIFICATION, RIGHT?
THESE ARE ALL HYDROLYSIS.
SO THAT'S WHAT WE'RE GOING TO--
IT'S AN IMPORTANT REACTION FOR BIOCHEMISTRY.
AND SO WHENEVER WE'RE LOOKING
AT HYDROLYSIS OF A CARBOXYLIC ACID DERIVATIVE,
WE FOCUS ON THE CARBONYL CARBON,
AND WE KNOW THE WATER IS GOING TO COME IN,
THE HYDROXYL GROUP WILL GO WITH THE CARBONYL,
AND THE HYDROGEN WITH, RIGHT, WHAT WE CALL THE Z GROUP.
AND SO HERE ARE THE HYDROXYL GROUPS, AND THE HYDROGENS.
AND THERE IS OUR CARBONYL CARBON. ALL RIGHT.
SO JUST REMEMBER EVERYTHING WE'VE LEARNED
ABOUT HYDROLYSIS, AND NOW APPLYING IT TO TRIGLYCERIDES.
SO HERE IS A MOLECULE FOR US TO PRACTICE ON, RIGHT?
SO HERE WE HAVE A TRIGLYCERIDE.
AND SO IF WE HAVE ONE MOLE OF TRIGLYCERIDE,
HOW MANY MOLES OF WATER ARE NEEDED?
ALL RIGHT, SO WE'RE DEFINITELY GOING TO NEED
THREE MOLES OF WATER
BECAUSE WE HAVE THREE ESTERS TO HYDROLYZE.
SO NOW LET'S GO AHEAD AND PREDICT THE PRODUCTS, RIGHT.
SO TO PREDICT THE PRODUCTS WE ARE GOING TO FOCUS
ON OUR CARBONYL CARBONS,
RECOGNIZING WHERE TO HYDROLYZE.
NOW, THERE'S NOT A LOT OF ROOM HERE SO I'M GOING TO SHOW,
RIGHT, THERE'S THE GLYCERIN BACKBONE,
WE'LL JUST SHOW THAT RIGHT HERE.
OKAY. AND WE KNOW--OOPS RIGHT.
AND SO WE KNOW THEN THAT THE HYDROGEN
FROM THE WATER COMES IN.
ALL RIGHT AND SO THEN THIS WILL BE THE GLYCEROL, RIGHT,
WHICH ALSO COULD BE CALLED GLYCERIN,
SO TWO NAMES FOR THE SAME STRUCTURE.
HERE WE GO.
NOW, COMES THE TRICKIER PART.
RIGHT, SO NOW WE NEED TO DRAW EACH OF THE FATTY ACIDS.
ALL RIGHTY, SO, THIS FIRST FATTY ACID--
I'M NOT SURE IF SKELETAL LINE WILL WORK.
I DON'T KNOW IF WE HAVE ENOUGH ROOM,
AND WE DON'T KNOW IF THEY'RE CIS OR TRANS,
SO LET'S JUST GO THIS WAY, RIGHT.
SO WE HAVE OUR TERMINAL CARBON,
AND THEN WE HAVE FOUR METHYLENE GROUPS,
AND THEN WE HAVE A DOUBLE BOND,
AND THEN ANOTHER METHYLENE, AND THEN ANOTHER DOUBLE BOND,
AND THEN WE HAVE A BUNCH OF METHYLENES,
AND THEN IT JUST FITS, WE HAVE OUR CARBOXYLIC ACID.
ALL RIGHT. SO THERE'S OUR FIRST FATTY ACID.
AND THEN WE WOULD HAVE THE SECOND FATTY ACID.
THIS ONE LOOKS A LITTLE SIMPLER TO DRAW.
NOW WE HAVE FIVE METHYLENES,
AND THEN COMES OUR DOUBLE BOND,
AND THEN WE HAVE ANOTHER SEVEN,
OH, THAT SHOULD HAVE BEEN A SEVEN,
AND THEN WE HAVE OUR CARBOXYLIC ACID GROUP,
AND THEN LAST BUT NOT LEAST WE HAVE A NICE
LITTLE SATURATED HYDROCARBON TAIL WITH OUR CARBOXYLIC ACID.
OKAY. SO WE HAVE FOUR PRODUCTS, RIGHT.
SO THESE ARE ALL OF OUR FATTY ACIDS.
AND NOTICE IN THIS EXAMPLE WE HAD A SATURATED, UNSATURATED,
AND POLYUNSATURATED, ALL WITHIN THE SAME TRIGLYCERIDE.
SO, ALL RIGHT. SO THERE'S THE MAIN SKILLS THAT WE NEED
FOR FATTY ACID AND TRIGLYCERIDES,
IS MAKING SURE THAT WE CAN HYDROLYZE THEM AND CLASSIFY--
DISTINGUISH BETWEEN SATURATED, UNSATURATED,
AND POLYUNSATURATED.
SO PLEASE TAKE SOME TIME NOW TO WORK HOMEWORK PROBLEMS
TO REINFORCE YOUR UNDERSTANDING.