METABOLISM

YOU MUST KNOW…• THE KEY ROLE OF ATP IN ENERGY

COUPLING• THAT ENZYMES WORK BY LOWERING

THE ENERGY OF ACTIVATION• THE CATALYTIC CYCLE OF AN

ENZYME THAT RESULTS IN THE PRODUCTION OF A FINAL PRODUCT

• THE FACTORS THAT INFLUENCE THE EFFICIENCY OF ENZYMES

CONCEPT 8.1• AN ORGANISM’S METABOLISM

TRANSFORMS MATTER AND ENERGY, SUBJECT TO THE LAWS OF THERMODYNAMICS

METABOLISM• THE TOTALITY OF

AN ORGANISM’S CHEMICAL REACTIONS

• MANAGES THE MATERIAL AND ENERGY RESOURCES OF THE CELL

CATABOLIC PATHWAY• LEADS TO THE RELEASE OF

ENERGY BY THE BREAKDOWN OF COMPLEX MOLECULES

TO SIMPLER

COMPOUNDS• EX. BREAKDOWN

OF FOOD

ANABOLIC PATHWAY• CONSUME ENERGY TO BUILD

COMPLICATED MOLECULES FROM SIMPLER ONES

• EX. LINKING a.a. TO FORM MUSCLE PROTEIN IN RESPONSE TO PHYSICAL EXERCISE

ENERGY• THE CAPACITY TO DO WORK• KINETIC ENERGY – ENERGY DURING

MOVEMENT• POTENTIAL ENERGY – STORED

ENERGY • CHEMICAL ENERGY – A FORM OF

POTENTIAL ENERGY WHERE ENERGY IS STORED IN MOLECULES AND THE AMOUNT DEPENDS ON ITS CHEMICAL BONDS

THERMODYNAMICS• STUDY OF ENERGY

TRANSFORMATIONS THAT OCCUR IN MATTER

• FIRST LAW OF THERMODYNAMICS – THE ENERGY OF THE UNIVERSE IS CONSTANT AND THAT ENERGY CAN BE TRANSFERRED AND TRANSFORMED, BUT CANNOT BE CREATED OR DESTROYED

THERMODYNAMICS• SECOND LAW OF THERMODYNAMICS

– EVERY ENERGY TRANSFER, OR TRANSFORMATION INCREASES THE ENTROPY OR THE AMOUNT OF DISORDER OR RANDOMNESS, IN THE UNIVERSE

CONCEPT 8.2• THE FREE-ENERGY CHANGE OF A

REACTION TELLS US WHETHER THE REACTION OCCURS SPONTANEOUSLY

FREE ENERGY• THE PART OF A SYSTEM’S ENERGY

THAT IS ABLE TO PERFORM WORK WHEN THE TEMPERATURE OF A SYSTEM IS UNIFORM

• INCLUDES EXERGONIC AND ENDERGONIC REACTIONS

EXERGONIC REACTION• ENERGY IS RELEASED• OCCUR SPONTANEOUSLY (THAT

DOESN’T NECESSARILY MEAN QUICKLY) AND RELEASE FREE ENERGY TO THE SYSTEM

ENDERGONIC REACION• REQUIRES ENERGY IN ORDER TO

PROCEED• ABSORB FREE ENERGY• THEY REQUIRE FREE ENERGY FROM

THE SYSTEM

CONCEPT 8.3• ATP POWERS CELLULAR WORK

BY COUPLING EXERGONIC REACTIONS TO ENDERGONIC REACTIONS

ENERGY COUPLING• THE WAY CELLS MANAGE THEIR

ENERGY RESOURCES TO DO CELL WORK

• THE USE OF AN EXERGONIC PROCESS TO DRIVE AN ENDERGONIC ONE

ATP• THE PRIMARY SOURCE OF ENERGY

FOR CELL IN ENERGY COUPLING• MADE UP OF THE NITROGENOUS

BASE ADENINE, RIBOSE, AND A CHAIN OF 3 PHOSPHATE GROUPS

• WHEN A PHOSPHATE GROUP IS HYDROLYZED, ENERGY IS RELEASED IN AN EXERGONIC REACTION

RELEASE OF ATP• WORK IN THE CELL IS DONE BY THE

RELEASE OF A PHOSPHATE GROUP FROM ATP

• THE EXERGONIC RELEASE OF THE PHOSPHATE GROUP IS USED TO DO THE ENDERGONIC WORK OF THE CELL

• WHEN ATP TRANSFERS ONE PHOSPHATE GROUP THROUGH HYDROLYSIS, IT BECOMES ADP

CONCEPT 8.4• ENZYMES SPEED UP METABOLIC

REACTIONS BY LOWERING ENERGY BARRIERS

CATALYSTS

• SUBSTANCES THAT CAN CHANGE THE RATE OF REACTION WITHOUT BEING ALTERED IN THE PROCESS

• ENZYMES ARE MACROMOLECULES THAT ARE BIOLOGICAL CATALYSTS

ACTIVATION ENERGY• THE AMOUNT OF ENERGY IT TAKES

TO START A REACTION• THE AMOUNT OF ENERGY IT TAKES

TO BREAK THE BONDS OF THE REACTANT MOLECULES

• ENZYMES SPEED UP REACTIONS BY LOWERING THE ACTIVATION ENERGY OF THE REACTION BUT WITHOUT CHANGING THE FREE ENERGY CHANGE OF THE REACTION

• THE ENZYME ACTS ON A SUBSTRATE

ACTIVE SITE• THE PART OF THE ENZYME

THAT BINDS TO THE SUBSTRATE

• FORMS AN ENZYME-SUBSTRATE COMPLEX THAT IS HELD TOGETHER BY WEAK INTERACTIONS

• SUBSTRATE IS THEN CONVERTED INTO PRODUCTS THAT ARE RELEASED FROM THE ENZYME

WHAT AFFECTS ENZYME ACTIVITY?

• CHANGES IN pH AND TEMPERATURE

• 3-D SHAPE IS CHANGED SO THE ENZYME WILL NOT

BE AS EFFECTIVE (DENATURES)

• MANY ENZYMES REQUIRE NONPROTEIN HELPERS CALLED COFACTORS TO FUNCTION PROPERLY

• ORGANIC COFACTORS ARE REFERRED TO AS COENZYMES

COMPETITIVE INHIBITORS• REVERSIBLE INHIBITORS THAT

COMPETE WITH THE SUBSTRATE FOR THE ACTIVE SITE ON THE ENZYME

• SIMILAR CHEMICALLY TO THE SUBSTRATE

• REDUCE THE EFFICIENCY OF THE ENZYME AS IT COMPETES FOR THE ACTIVE SITE

NONCOMPETITIVE INHIBITORS• DO NOT DIRECTLY COMPETE WITH

THE SUBSTRATE• IMPEDE ENZYME ACTIVITY BY

BINDING TO ANOTHER PART OF THE ENZYME

• CAUSES ENZYME TO CHANGE SHAPE MAKING THE ACTIVE SITE NONFUNCTIONAL

CONCEPT 8.5• REGULATION OF ENZYME

ACTIVITY HELPS CONTROL METABOLISM

ALLOSTERIC SITE• A SPECIFIC BINDING SITE BUT NOT

THE ACTIVE SITE• ONCE BOUND, THE SHAPE OF THE

ENZYME IS CHANGE AND IT CAN EITHER STIMULATE OR INHIBIT ENZYME ACTIVITY

FEEDBACK INHIBITION• A TYPE OF

ALLOSTERIC

INHIBITION• IT INCREASES THE EFFICIENCY

OF THE PATHWAY BY TURNING IT OFF WHEN THE END PRODUCT ACCUMULATES IN THE CELL