Regents Biology 2009-2010

Enzymes – Chapter 2.4

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A. Flow of energy

Life is built on chemical reactions

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B. Chemical reactions of life Processes of life

building macromolecules Dehydration synthesis

breaking down macromolecules Hydrolysis

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C. Enzymes How important are enzymes?

all chemical reactions in living organisms require enzymes to work

enzymes speed up reactionsAct as catalysts

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enzyme

enzyme

We can’t live without enzymes!

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D. Activation Energy Is energy needed to get a reaction

started Enzymes act by lowering the activation

energy

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E. Enzymes are proteins Each enzyme is the specific helper to

a specific reactionneeds to be the right shape are named for the reaction they help

sucrase breaks down sucroseDNA polymerase builds

DNA

Oh, I get it!They end

in -ase

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F. Enzymes aren’t used up Enzymes are not changed by the

reactionused only temporarilyre-used again for the same reaction

enzyme

substrate product

active site

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G. It’s shape that matters! Lock & Key model

shape of enzyme & substrate must ‘fit’

specific enzyme for each reaction

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H. What affects enzyme action? Correct protein structure (amino acid

chain) Temperature pH (acids & bases)

why? enzyme has to be right shape

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I. Temperature Effect on rates of enzyme activity

Optimum temperaturegreatest number of collisions

between enzyme & substratehuman enzymes

35°- 40°C Raise temperature (boiling)

denature protein = unfold = lose shape

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37°

Temperature

temperature

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tio

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What’s happening here?!

What is optimum temp for human enzymes?

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J. pH Effect on rates of enzyme activity

changes in pH changes protein shape

most human enzymes = pH 6-8 pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8

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pH

pH

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stomachpepsin

intestinestrypsin

What’s happening here?!

11 12 13 14

Which environment does pepsin work best – acidic or basic?

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How do cold-blooded creatures do it?

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For enzymes…What matters?

SHAPE!

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Enzyme vocabulary Enzyme

helper protein molecule Substrate

molecule that enzymes work on Products

what the enzyme helps produce from the reaction

Active site part of enzyme

that substrate molecule fits into

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Order of amino acids Wrong order = wrong shape = can’t do its job!

DNA

DNA

chain ofamino acids

chain ofamino acids

foldedprotein

foldedprotein

right shape!

wrong shape!

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Examples synthesis

digestion

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enzyme

enzyme