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BIO. 1300/1400 CHAPTER 5—ENZYMES. ENZYME—AN ORGANIC CATALYST—SPEEDS UP A REACTION BUT IS NOT USED UP IN THE REACTION. ENZYMES. THE ENDING OR SUFFIX OF A WORD LETS YOU KNOW IF IT IS THE NAME OF AN ENZYME IF THE WORD ENDS IN –ASE THEN IT IS AN ENZYME—EXAMPLES ARE: SUCRASE LACTASE MALTASE.
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BIO. 1300/1400CHAPTER 5—ENZYMES ENZYME—AN ORGANIC CATALYST—SPEEDS UP A REACTION BUT IS NOT USED UP IN THE REACTION
ENZYMES • THE ENDING OR SUFFIX OF A WORD LETS YOU KNOW IF IT IS THE NAME OF AN ENZYME • IF THE WORD ENDS IN –ASE THEN IT IS AN ENZYME—EXAMPLES ARE: • SUCRASE • LACTASE • MALTASE
ENERGY OF ACTIVATION • THE ENERGY OF ACTIVATION IS THE AMOUNT OF ENERGY IT TAKES TO START A REACTION • ENZYMES LOWER THE ENERGY OF ACTIVATION
HOW ENZYMES WORK • ENZYMES COMBINE WITH THE SUBSTRATE [REACTANT] TO FORM THE ENZYME-SUBSTRATE COMPLEX • THE ENZYME HAS A SPECIFIC AREA TO WHICH THE SUBSTRATE ATTACHES CALLED THE BINDING SITE OR ATTACHMENT SITE • WHEN THE REACTION IS COMPLETED THEN THE PRODUCTS ARE RELEASED AND THE ENZYME IS FREE TO ACT AGAIN
COFACTORS/COENZYMES ADDITIONAL MOLECULES OR COMPOUNDS WHICH ARE NEEDED BY ENZYMES THAT ALLOW THEM TO WORK ELEMENTS OR ORGANIC MOLECULES ARE COFACTORS IF THE COFACTOR IS NOT A PROTEIN BUT ANOTHER ORGANIC COMPOUND IT IS CALLED A COENZYME. IT ACTS TO BRING IN PART OF THE SUBSTRATE OR TO REMOVE SOME OF THE END PRODUCTS ONE EXAMPLE IS CO-ENZYME A WHICH WORKS IN BRINGING CARBONS INTO THE KREB’S CYCLE IN THE MITOCHONDRIA.
FACTORS INFLUENCING ENZYMES- TEMPERATURE AND pH • TEMPERATURE—WITH OPTIMUM TEMPERATURE THE TURNOVER NUMBER IS GREATEST • AS TEMPERATURE RISES PAST THE OPTIMUM THEN THE ENZYME IS ALTERED OR DENATURED AND THE TURNOVER NUMBER DECREASES • A DENATURED ENZYME HAS ITS PROTEIN STRUCTURE PERMANENTLY CHANGED
FACTORS CONTINUED • THE ACID-BASE CONDITION OR pH WILL INFLUENCE THE ENZYMES ABILITY TO ACT. • THE OPTIMUM pH WILL ALLOW THE GREATEST RATE OF REACTION • WHEN THE pH CHANGES THEN THE ENZYME WILL BE DENATURED
CELLULAR CONTROL PROCESSES AND ENZYMES • CONTROL PROCESSES IN A CELL ARE LINKED TO THE ENZYMES IN THE CELL AND THE ORDER IN WHICH THEY WORK. • ENZYMATIC COMPETITION—OCCURS WHEN SEVERAL ENZYMES ARE PRESENT THAT CAN COMBINE WITH THE SAMESUBSTRATE • NEGATIVE-FEEDBACK INHIBITION—OCCURS WHEN THE END PRODUCT OF A REACTION FEEDS BACK TO THE FIRST ENZYME OF THE REACTION AND INHIBITS IT FROM WORKING SLOWING DOWN OR STOPPING THE REACTION • INHIBITORS ARE MOLECULES WHICH ATTACH TO AN ENZYME AND PREVENT IT FROM WORKING—SOME PESTICIDES WORK THIS WAY. COMPETITIVE INHIBITION –THE INHIBITOR COMPETES WITH THE SUBSTRATE FOR THE ENZYME.