CELL RESPIRATION

YOU MUST KNOW… THE DIFFERENCE BETWEEN FERMENTATION AND CELLULAR RESPIRATION THE ROLE OF GLYCOLYSIS IN OXIDIZING GLUCOSE TO TWO MOLECULES OF PYRUVATE

YOU MUST KNOW… THE PROCESS THAT BRINGS PYRUVATE FROM THE CYTOSOL INTO THE MITOCHONDRIA AND INTRODUCES IT INTO THE CITRIC ACID CYCLE HOW THE PROCESS OF CHEMIOSMOSIS UTILIZES THE ELECTRONS FROM NADH AND FADH2 TO PRODUCE ATP

CONCEPT 9.1 CATABOLIC PATHWAYS RELEASE ENERGY BY OXIDIZING ORGANIC FUELS

CATABOLIC PATHWAYS OCCURS WHEN MOLECULES ARE BROKEN DOWN AND THEIR ENERGY IS RELEASED FERMENTATION – THE PARTIAL DEGRADATION OF SUGARS THAT OCCURS WITHOUT THE USE OF OXYGEN (ANAEROBIC) CELLULAR RESPIRATION – OXYGEN IS CONSUMED AS A REACTANT ALONG WITH THE ORGANIC FUEL (ALSO TERMED AEROBIC)

CELL RESPIRATION GLUCOSE IS THE PRIMARY NUTRIENT MOLECULE USED C6H12O6 + 6 O2  6 H20 + ENERGY (686 KCAL/MOLE OF GLUCOSE) CARBON DIOXIDE AND HEAT ARE BY- PRODUCTS

DURING KEY STEPS IN CR, ELECTRONS ARE STRIPPED FROM GLUCOSE EACH ELECTRON TRAVELS WITH A PROTON, FORMING A HYDROGEN ATOM THE HYDROGEN ATOMS ARE NOT TRANSFERRED DIRECTLY TO OXYGEN BUT ARE PASSED TO AN ELECTRON CARRIER, THE COENZYME NAD+

NAD+ ACCEPTS 2 ELECTRONS AND THE STABILIZING HYDROGEN ION TO FORM NADH NADH HAS BEEN REDUCED AND HAS GAINED ENERGY

THE EXERGONIC RELEASE OF ENERGY FROM GLUCOSE IS USED TO PHOSPHORYLATE ADP TO ATP CALLED OXIDATION-REDUCTION REACTIONS (REDOX) IN REDOX REACTIONS, ELECTRONS ARE TRANSFERRED FROM ONE REACTANT TO ANOTHER

OXIDATION – LOSS OF ONE OR MORE ELECTRONS FORM A REACTANT REDUCTION – GAIN OF ONE OR MORE ELECTRONS (INCREASE IN ENERGY)

CONCEPT 9.2 GLYCOLYSIS HARVESTS CHEMICAL ENERGY BY OXIDIZING GLUCOSE TO PYRUVATE

GLYCOLYSIS OCCURS IN CYTOSOL GLUCOSE IS BROKEN DOWN IN TO 2 PYRUVATE MOLECULES THROUGH A SERIES OF STEPS 2 ATP HELP TO DESTABILIZE GLUCOSE

GLYCOLYSIS GLUCOSE  2 PYRUVATE + 2 H20 4 ATP FORMED – 2 ATP USED 2 ATP 2 NAD+ + 4 e- + 4 H+  2 NADH + 2 H+

CONCEPT 9.3 THE CITRIC ACID CYCLE COMPLETES THE ENERGY-YIELDING OXIDATION OF ORGANIC MOLECULES

CITRIC ACID CYCLE PYRUVATE, IN THE CYTOSOL, USES A TRANSPORT PROTEIN TO MOVE INTO THE MATRIX OF THE MITOCHONDRIA AN ENZYME COMPLEX REMOVES A CO2, STRIPS AWAY ELECTRONS TO CONVERT NAD+ TO NADH, AND ADDS COENZYME A TO FORM ACETYL CoA 2 ACETYL CoA MOLECULES ARE PRODUCED PER GLUCOSE

CITRIC ACID CYCLE BY THE END, THE 6 CARBON FROM GLUCOSE HAVE BEEN RELEASED AS CO2 2 ATP ARE PRODUCED THE REMAINDER OF ENERGY IS HELD IN THE ELECTRONS IN THE ELECTRON CARRIERS, NADH AND FADH2 ENERGY IS UTILIZED BY THE ETC

CONCEPT 9.4 DURING OXIDATIVE PHOSPHORYLATION, CHEMIOSMOSIS COUPLES ELECTRON TRANSPORT TO ATP SYNTHESIS

ETC EMBEDDED IN THE INNER MEMBRANE OF THE MITOCHONDRIA IT IS COMPOSED OF 3 TRANSMEMBRANE PROTEINS THAT WORK AS HYDROGEN PUMPS AND TWO CARRIER MOLECULES THAT TRANSPORT ELECTRONS BETWEEN HYDROGEN PUMPS THERE ARE THOUSANDS OF ETCs/INNER MITOCHONDRIAL MEMBRANE

IT IS POWERED BY NADH AND FADH2 THE LOSS OF ENERGY BY THE ELECTRONS IS USED TO POWER THE PUMPING OF PROTONS ACROSS THE MEMBRANE AT THE END OF THE ETC, THE ELECTRONS COMBINE WITH 2 HYDROGEN IONS AND OXYGEN TO FORM WATER OXYGEN IS THE FINAL ELECTRON ACCEPTOR AND IF IT IS NOT AVAILABLE, IT COMES TO A HALT AND NO ATP IS PRODUCED

THE HYDROGEN IONS FLOW THROUGH A TRANSMEMBRANE PROTEIN KNOWN AS ATP SYNTHASE ATP SYNTHASE HARNESSES THE PROTON MOTIVE FORCE – THE GRADIENT OF HYDROGEN IONS – TO PHOSPHORYLATE ADP, FORMING ATP THIS FORCE HOLDS ELECTRONS BEHIND THE INNER MEMBRANE WITH THE ONLY EXIT ATP SYNTHASE

CHEMIOSMOSIS ENERGY-COUPLING MECHANISM THAT USES ENERGY STORED IN THE FORM OF AN H+ GRADIENT ACROSS A MEMBRANE TO DRIVE ATP SYNTHESIS THE ETC AND CHEMIOSMOSIS COMPOSE OXIDATIVE PHOSPHORYLATION (ADP IS PHOSPHORYLATED AND OXYGEN IS NEEDED TO KEEP THE ELECTRONS FLOWING)

ATP YIELD PER MOLECULE OF GLUCOSE IS BETWEEN 36-38 ATP OXIDATIVE PHOSPHORYLATION PRODUCES 32-34 OF THE TOTAL

CONCEPT 9.5 FERMENTATION ENABLES SOME CELLS TO PRODUCE ATP WITHOUT THE USE OF OXYGEN

FERMENTATION CELL CAN PRODUCE ATP UNDER ANAEROBIC CONDITIONS CONSISTS OF GLYCOLYSIS PRODUCES A NET OF 2 ATP AND REACTIONS THAT REGENERATE NAD+

ALCOHOL FERMENTATION PYRUVATE IS CONVERTED TO ETHANOL, RELEASING CARBON DIOXIDE AND OXIDIZING NADH IN THE PROCESS TO CREATE MORE NAD+

LACTIC ACID FERMENTATION PYRUVATE IS REDUCED BY NADH (NAD+ IS FORMED IN THE PROCESS), AND LACTATE IS FORMED AS A WASTE PRODUCT

CONCEPT 9.6 GLYCOLYSIS AND THE CITRIC ACID CYCLE CONNECT TO MANY OTHER METABOLIC PATHWAYS

IN ADDITION TO GLUCOSE, OTHER SUGARS, PROTEINS, AND FATS ARE OFTEN USED TO GENERATE ATP THROUGH CELL RESPIRATION ORGANIC MOLECULES ARE USED IN BIOSYNTHESIS, THE BUILDING OF MACROMOLECULES THROUGH ANABOLIC PATHWAYS