Regents Biology

Warm UpBase your answer to this question on the diagram below, which represents stages in the digestion of a starch, and on your knowledge of biology.

The products would most likely containA. simple sugars. C. amino acids.B. fats. D. minerals.

Regents Biology 2009-2010

Enzymes:

“Helper” Protein molecules

Regents Biology

Chemical ReactionsA. When bonds are broken and reformed to

make different substances.EX:

Reactants Products C6H12O6 + 6O2 6CO2 + 6H2O

Regents Biology

Chemical reactions of life Processes of life

A. building molecules = synthesis

B. breaking down molecules = digestion

+

+

Regents Biology

What is needed to start a reaction?

Ener

gy a

bsor

bed

Activation energy

Reactant

Products

Ener

gy re

leas

ed

Regents Biology

Nothing works without enzymes! How important are enzymes?

A. all chemical reactions in living organisms require enzymes to work building molecules = synthesis enzymes

breaking down molecules = digestive enzymes

+

enzyme

+

enzyme

We can’t live without enzymes!

Regents Biology

B. enzymes speed up reactions = catalysts

Regents Biology

C. Digestion Reaction Is the breakdown of a complex molecule into

simpler substances These reactions RELEASE energy

Enzyme EnzymeEnzymeEnzyme

Regents Biology

D. Synthesis Reaction The combining of simple molecules into a

more complex ones This reaction builds new molecules and/or

STORES energy

Enzyme EnzymeEnzyme

ProductsReactants

Regents Biology

Examples Synthesis

Digestion

+

+

enzyme

enzyme

Regents Biology

Enzymes are proteins & each enzyme is the specific helper to a specific reaction.

A. Each enzyme needs to be the right shape for the jobB. Enzymes are named for the reaction they help

i. sucrase breaks down sucroseii. proteases breakdown proteinsiii. lipases breakdown lipidsiv. DNA polymerase builds DNA

Oh, I get it!They end

in -ase

Regents Biology

Enzymes aren’t used up**Enzymes are NOT changed by the reaction

A. used only temporarilyB. re-used again for the same reaction with other

moleculesC. very little enzyme needed to help in many reactions

enzyme

substrate product

active site

Regents Biology

It’s shape that matters! Lock & Key Theory

A. shape of protein allows enzyme & substrate to fit

B. specific enzyme for each specific reaction

Substrate

Enzyme

Products

Regents Biology

What Affects Enzyme Activity

Temperature:

pH:0 3 75 9 11 13

Neutral

Battery Acid BleachBlood (7.5)

Regents Biology

Temperature & Effect on Rates of Enzyme ActivityA. Optimum (best) temperature

i. greatest number of collisions between enzyme & substrate

ii. human enzymes = 35°- 40°C (body temp = 37°C)

B. Raise temperature (boiling)i. denature protein = unfold = lose shape

C. Lower temperature i. molecules move slower ii. fewer collisions between enzyme & substrate

Regents Biology

37°

Temperature

Temperature ( + C)

Rea

ctio

n R

ate

What’s happening here?!

humanenzymes

Regents Biology

pH & Effect on Rates of Enzyme Activity A. changes in pH = changes protein shape

B. most human enzymes work best at pH 6-8i. depends on where in body

ii. pepsin (stomach) = pH 3

iii. trypsin (small intestines) = pH 8

Regents Biology

7

pH

pH

reac

tio

n r

ate

20 1 3 4 5 6 8 9 10

stomachpepsin

intestinestrypsin

What’s happening here?!

11 12 13 14

Regents Biology

DenatureA. When enzymes are exposed to extreme pH or high

temperatures, they can denatureB. When denatured, an enzyme will no longer

function, due to a change in enzyme structureC. This is why running high fevers for extended time

is cause for concern

Regents Biology

Enzyme vocabulary review Enzyme

Protein; speeds up chemical reactions by lowering activation energy

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