HOW CELLS HARVEST CHEMICAL
ENERGY
HOW CELLS HARVEST CHEMICAL
ENERGY
• TWO FORMS OF RESPIRATION
– RESPIRATION = BREATHING
• BREATHING IS ??
– CELLULAR RESPIRATION
• DEFINITION??
HOW CELLS HARVEST CHEMICAL
ENERGY
• CELLULAR RESPIRATION
– FORMULA??
– VERY EFFICIENT ENERGY CONVESION
– PRODUCES ??
– WHAT IS THE MAJORITY OF ENERGY USED FOR?
HOW CELLS HARVEST CHEMICAL
ENERGY
• CELLULAR RESPIRATION DISMANTLES
GLUCOSE IN A SERIES OF ENERGY RELEASING
STEPS, STORING THIS RELEASED ENERGY AS
ATP
• WHERE DOES THE ENERGY IN GLUCOSE COME
FROM?
– ELECTRONS TRANSFERS!!
• REACTIONS INVOLVING THE TRANSFER OF
ELECTRONS ARE CALLED REDOX REACTIONS
HOW CELLS HARVEST CHEMICAL
ENERGY
• REDOX REACTIONS
– THE MOVEMENT OF ELECTRONS FROM ONE
MOLECULE TO ANOTHER
HOW CELLS HARVEST CHEMICAL
ENERGY
• REDOX REACTIONS
– OXIDATION VS REDUCTION
• OIL RIG (OXIDATION IS LOSS; REDUCTION IS GAIN)
• LEO GOES GER (LOSE ELECTRONS OXIDATION; GAIN
ELECTRONS REDUCTION)
• IN CELLULAR RESPIRATION NAD IS AN
ELECTRON CARRIER (TAXI)
HOW CELLS HARVEST CHEMICAL
ENERGY
• REDOX REACTIONS RELEASE ENERGY WHEN
ELECTRONS “FALL” FROM ELECTRON CARRIER
TO OXYGEN
– ELECTRON CARRIERS??
– ELECTRON TRANSPORT CHAINS??
• WHY ARE THESE NECESSARY?
HOW CELLS HARVEST CHEMICAL
ENERGY
HOW CELLS HARVEST CHEMICAL
ENERGY
• TWO MECHANISMS GENERATE ATP
– CHEMIOSMOSIS + ATP SYNTHASE
– SUBSTRATE LEVEL PHOSPHORYLATION
HOW CELLS HARVEST CHEMICAL
ENERGY
HOW CELLS HARVEST CHEMICAL
ENERGY
• HOW DOES THE CELL UTILIZE THESE ENERGY
CONVERSION MECHANISMS?
• CELLULAR RESPIRATION!!
HOW CELLS HARVEST CHEMICAL
ENERGY
HOW CELLS HARVEST CHEMICAL
ENERGY
• THREE MAIN STAGES
– GLYCOLYSIS
– KREBS CYCLE
– ELECTRON TRANSPORT CHAIN (E.T.C)
HOW CELLS HARVEST CHEMICAL
ENERGY
• GLYCOLYSIS
– HARVESTS CHEMICAL ENERGY BY OXIDIZING
GLUCOSE TO PYRUVIC ACID
HOW CELLS HARVEST CHEMICAL
ENERGY
• GLYCOLYSIS
– “SPLITTING OF SUGAR”
– GLUCOSE IS CHANGED TO PYRUVIC ACID IN A
SERIES OF 9 STEPS
– WHO WANTS TO MEMORIZE ALL 9 STEPS??
HOW CELLS HARVEST CHEMICAL
ENERGY
• LET’S LOOK AT THE
CLIFF’S NOTES VERSION

HOW CELLS HARVEST CHEMICAL
ENERGY
• MAJOR POINTS ABOUT GLYCOLYSIS
– OCCURS IN THE CYTOPLASM
– REQUIRES INITIAL INPUT OF ENERGY (2 ATP) TO BEGIN
REACTION (IT TAKES MONEY TO MAKE MONEY)
– GLUCOSE  PYRUVIC ACID
– 1 6-CARBON COMPOUND  2 3-CARBON
COMPOUNDS
– OVERALL GLYCOLYSIS REACTION??
– PRODUCES A SMALL AMOUNT OF ENERGY, WHICH IS
SUFFICIENT FOR BACTERIA, OR YEAST, TO SURVIVE,
BUT NOT FOR LARGER ORGANISMS
HOW CELLS HARVEST CHEMICAL
ENERGY
• WHAT HAPPENS NEXT??
• *GROOMING PHASE*
– PYRUVIC ACID DIFFUSES INTO THE
MITOCHONDRIA AND IS ‘GROOMED’
HOW CELLS HARVEST CHEMICAL
ENERGY
•
•
•
•
WHY DOES THE GROOMING PHASE OCCUR?
WHAT ARE THE REACTANTS?
WHAT ARE THE PRODUCTS?
WHAT DOES IT LOOK LIKE OVERALL?
HOW CELLS HARVEST CHEMICAL
ENERGY
• KREBS CYCLE
HOW CELLS HARVEST CHEMICAL
ENERGY
• KREBS CYCLE
– DISASSEMBLES ACETYL-COA AND FORMS ENERGY
STORING MOLECULES AND CO2
– WORKS ON EACH PYRUVATE; SINCE 2 PYRUVATES
WERE MADE THE CYCLE OCCURS 2X!!
HOW CELLS HARVEST CHEMICAL
ENERGY
• KREB CYCLE
– ALSO CALLED
CITRIC ACID CYCLE
– WHO WANTS TO
MEMORIZE THIS 
HOW CELLS HARVEST CHEMICAL
ENERGY
• LET’S CREATE A SIMPLER DIAGRAM…SHALL WE??
• WHAT ARE THE MAIN POINTS??
–
–
–
–
OCCURS IN THE MITOCHONDRIAL MATRIX
EACH TURN PRODUCES 1 ATP, 3 NADH, AND 1 FADH2
OCCURS 2X (1X FOR EACH PYRUVATE MOLECULE)
RESPONSIBLE FOR PRODUCTION OF CO2 THAT WE
EXHALE (WHERE DID THIS CO2 COME FROM?)
– PRODUCES A LOT OF HIGH ENERGY CARRIERS, BUT
NOT MUCH USEABLE ENERGY (ATP)
HOW CELLS HARVEST CHEMICAL
ENERGY
• LET’S SUM UP WHAT WE HAVE SO FAR:
HOW CELLS HARVEST CHEMICAL
ENERGY
• THE ENERGY IN NADH AND FADH2 MUST BE
RELEASED
• ENTER THE ELECTRON TRANSPORT CHAIN!!
– CHEMIOSMOSIS + ATP SYNTHASE!!
HOW CELLS HARVEST CHEMICAL
ENERGY
• ELECTRON TRANSPORT CHAIN
– USES THE ENERGY OF THE ELECTRONS TO CREATE A
PROTON (H+) GRADIENT ACROSS THE INNER
MEMBRANE OF THE MITOCHONDRIA
• CHEMIOSMOSIS
– THE DIFFUSION OF THE H+ ION ACROSS THE INNER
MEMBRANE
– POWERS ATP PRODUCTION
• ATP SYNTHASE
– ENZYME EMBEDDED IN INNER MITOCHONDRIAL
MEMBRANE THAT ACTUALLY MAKES THE ATP
HOW CELLS HARVEST CHEMICAL
ENERGY
HOW CELLS HARVEST CHEMICAL
ENERGY
• WHY ARE CYANIDE AND CARBON MONOXIDE
POISONOUS??
– BLOCK ELECTRON FLOW, SO THEY PREVENT ??
HOW CELLS HARVEST CHEMICAL
ENERGY
• OXYGEN ACTS AS THE FINAL ELECTRON
ACCEPTOR!!
– COMBINES WITH ELECTRONS AND H+ IONS TO
FORM WATER!!
• ATP SYNTHASE CAN PRODUCE ANYWHERE
FROM 32-34 ATP’S PER GLUCOSE OXIDIZED!!
HOW CELLS HARVEST CHEMICAL
ENERGY
HOW CELLS HARVEST CHEMICAL
ENERGY
• LET’S SUM UP OUR REACTIONS!!
HOW CELLS HARVEST CHEMICAL
ENERGY
• WHAT HAPPENS IF THERE IS NO OXYGEN??
– ELECTRON TRANSPORT CHAIN CAN’T OCCUR
– KREBS CYCLE CAN’T OCCUR
• GLYCOLYSIS IS THE ONLY ANAEROBIC PROCESS
– BUT THERE ARE A FINITE NUMBER OF NAD+
AVAILABLE, SO WHAT DOES THAT MEAN?
HOW CELLS HARVEST CHEMICAL
ENERGY
HOW CELLS HARVEST CHEMICAL
ENERGY
• WHAT IS FERMENTATION??
– DEFINITION?
– TWO TYPES
• ALCOHOLIC VS LACTIC ACID
HOW CELLS HARVEST CHEMICAL
ENERGY
• AEROBES VS ANAEROBES?
• STRICT ANAEROBES?
• FACULTATIVE ANAEROBES?
HOW CELLS HARVEST CHEMICAL
ENERGY
• WHERE DOES ALL THE ENERGY IN GLUCOSE
COME FROM TO BEGIN WITH??
TUNE IN
NEXT TIME
TO FIND OUT
MORE!!!!