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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
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
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
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