- OKAY. WELCOME TO THE VIDEO TUTORIAL
THAT WILL GIVE AN OVERVIEW OF ESTERS
BECAUSE THEY COME IN SEVERAL FLAVORS.
THERE'S CARBOXYLIC ESTERS, THIOESTERS, AND PHOSPHOESTERS.
SO LET'S TAKE A LOOK. WE CAN SEE HERE THE ASPIRIN.
ASPIRIN IS A GREAT EXAMPLE. WE CAN RECOGNIZE THE ESTER THERE.
SO WE WOULD DESCRIBE THIS AS AN ESTER.
AND MANY TIMES WHEN YOU JUST HEAR THE WORD ESTER,
IT'S UNDERSTOOD TO BE A CARBOXYLIC ESTER
BECAUSE IT'S A DERIVATIVE OF A CARBOXYLIC ACID.
AND SO, WE WOULD GIVE THE CONDENSED FORMULA OF--
OR WE CAN HAVE THIS GENERIC STRUCTURE HERE OF R, O,
THE DOUBLE O, R PRIME, RIGHT,
FOR THE CONDENSED FORMULA, CO2R PRIME. ALL RIGHT.
AND SO, HERE IS THE ESTER GROUP. ALL RIGHTY.
NOW, WE BECOME AWARE THAT WE CAN REPLACE OXYGEN WITH SULFUR.
SO THEN, THIS WOULD BE AN EXAMPLE OF A THIOESTER.
AND SO WE COULD WRITE THAT GENERICALLY LIKE THIS
AND HERE WE GO. ALL RIGHT.
SO, THERE'S OUR THIOESTER
AND ACETYL-COENZYME "A" IS VERY IMPORTANT
IN AN ENERGY PRODUCTION
AND WE'LL SEE THAT A LOT MORE LATER IN THE SEMESTER.
AND SO, THE CONDENSED FORM HERE WOULD BE WRITTEN LIKE THIS.
ALL RIGHT. NOW,
PHOSPHATE ESTERS ARE A LITTLE MORE COMPLICATED
BECAUSE PHOSPHORUS IS A THIRD PERIOD ELEMENT
AND SO IT'S ALLOWED TO HAVE AN EXPANDED OCTET.
NOTICE THAT PHOSPHORUS IS NOT LIMITED BY THE OCTET RULE.
SO, LET'S START BY LOOKING AT PHOSPHORIC ACID.
SO, HERE WE HAVE THE STRUCTURE OF PHOSPHORIC ACID.
SO, WHAT MAKES PHOSPHATE GROUP SO IMPORTANT TO OUR BIOCHEMISTRY
IS BASICALLY THERE'S THREE ARMS COMING OFF.
EACH OF THESE ARMS,
THE HYDROGENS CAN BE REPLACED WITH R GROUPS.
NOW THIS MOLECULE IS SHOWN IN A BIOLOGICAL ENVIRONMENT
AND SO WE RECOGNIZE THAT THESE ARE ALL ACIDIC PROTONS.
SO, IN A BIOLOGICAL ENVIRONMENT,
THE PHOSPHATE GROUP IS DEPROTEINATED.
HOW THE PHOSPHATE ESTER FORMS IS THIS HYDROGEN ATOM RIGHT HERE
HAS BEEN REPLACED BY THIS GLUCOSE MOLECULE.
SO WE WOULD DESCRIBE THIS COMPOUND RIGHT HERE
AS A PHOSPHATE ESTER.
IN PARTICULAR, BECAUSE THIS IS A GLUCOSE MOLECULE,
WE COULD SAY THIS IS G-6-P FOR GLUCOSE-6-PHOSPHATE.
AND RIGHT NOW, THE EMPHASIS
IS JUST TO RECOGNIZE THE FUNCTIONAL GROUPS
THEN WE'LL COME BACK TO THIS LATER
WHEN WE STUDY BIOCHEMISTRY.
SO THEN, THIS BOND RIGHT HERE
IS DESCRIBED AS THE PHOSPHOESTER BOND
BECAUSE IT LINKS THE PHOSPHATE GROUP TO THE R GROUP.
AND WHY THIS IS IMPORTANT IS BECAUSE THE PHOSPHATE GROUPS
HAVE THE ABILITY TO LINK TOGETHER.
AND SO, IF WE'RE LOOKING, HERE'S AN EXAMPLE OF--
THIS IS ADENOSINE DIPHOSPHATE, SO THIS IS ADP.
AND SO, IF WE WERE LOOKING HERE, THIS BOND RIGHT HERE,
WE WOULD DESCRIBE AS THE PHOSPHOESTER BOND.
AND THEN, WHEN THE TWO-- AND SO THIS PHOSPHATE GROUP HERE
THEN LINKS TO A SECOND PHOSPHATE GROUP.
AND SO THIS BOND RIGHT HERE
WOULD BE THE PHOSPHOANHYDRIDE BOND.
SO, WHEN YOU'RE READING ABOUT BIOCHEMICAL REACTIONS,
WE WILL SEE ALL THESE PHOSPHATE GROUPS LINKED TOGETHER
AND SO IT'S IMPORTANT THAT WHEN YOU'RE READING AN EXPLANATION,
YOU RECOGNIZE THE DIFFERENCE
BETWEEN THE PHOSPHOANHYDRIDE BOND AND THE PHOSPHOESTER BOND.
THEN, FORTUNATELY FOR US,
THESE PHOSPHOANHYDRIDE BONDS WERE ABLE TO MAKE AND REFROM--
OR BREAK AND REFORM THESE BONDS AND WE USE THAT
IN ENERGY PRODUCTION.
SO LET'S LOOK AT OUR NEXT HANDOUT, NEXT PAGE,
AND JUST SHOW YOU THE CONTEXT.
SO THIS WAS NOT LIKE A REAL SUPER-EMPHASIZED POINT
FOR RIGHT NOW, BUT DOWN THE ROAD,
HERE IS A MOLECULE OF ATP.
AND SO, WHEN WE'RE LOOKING AT ATP,
HERE IS THE PHOSPHOESTER BOND AND THIS IS A STRONGER BOND,
THIS BOND IS NOT GOING TO BREAK VERY EASILY.
HOWEVER, THIS IS THE ONE WE CARE THE MOST ABOUT
AND I SHOULD PUT THAT IN GREEN.
THIS IS THE IMPORTANT BOND HERE FOR ENERGY TRANSPORT
BECAUSE OUR BODY STORES AND TRANSPORTS ENERGY
IN THIS PHOSPHOANHYDRIDE BOND RIGHT HERE,
SO, PHOSPHOANHYDRIDE.
OKAY SO THIS IS THE BOND THAT'S CONTINUALLY MADE AND REFORMED
AS ATP AS CONVERTED BACK AND FORTH FROM ADP.
SO, THROUGH THE GAIN AND LOSS
OF THIS PHOSPHATE GROUP RIGHT HERE, RIGHT.
SO, AS WE LOSE THE PHOSPHATE GROUP,
ENERGY IS RELEASED THAT WE CAN USE FOR WORK.
AND THEN WHEN WE PUT THE PHOSPHATE BACK ON,
ENERGY HAS TO COME IN.
SO, ENERGY IN AND ENERGY OUT
AND THAT ENERGY IS ALL RELATED TO THE ENERGY HELD
IN THIS PHOSPHOANHYDRIDE BOND RIGHT HERE.
SO WE GO FROM ATP TO ADP.
AND SO WHEN WE GET--STUDY BIOENERGETICS IN THE FUTURE,
WE'LL WANT TO COME BACK TO THIS REFERENCE.
SO, THE MAIN POINT OF THIS TUTORIAL WAS TO MAKE YOU AWARE
OF THE THREE DIFFERENT TYPES OF ESTERS
AND THE DIFFERENCE BETWEEN THE PHOSPHOESTER
AND PHOSPHOANHYDRIDE BOND.
SO I HOPE YOU'LL FIND THIS INFORMATION USEFUL
AS YOU GET TO WORK ON YOUR HOMEWORK
TO REINFORCE YOUR UNDERSTANDING.