control metabolism metabolic reactions can be controlled and sped up by enzymes that lower the...
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Control METABOLISMControl METABOLISM
Metabolic reactions can be controlled and Metabolic reactions can be controlled and sped up by enzymes that lower the sped up by enzymes that lower the activation energy needed.activation energy needed.– metabolic reactions would be too slow to metabolic reactions would be too slow to
occur if no enzymes were present!occur if no enzymes were present!
Properties of EnzymesProperties of Enzymes1.1. ProteinsProteins2.2. CatalystsCatalysts3.3. Reusable Reusable 4.4. Substrate Substrate
specificspecific5.5. Sensitive to Sensitive to
temperaturetemperature6.6. Sensitive to Sensitive to
pHpH
Enzymes remain unchanged!Enzymes remain unchanged!
Enzymes are Enzymes are not used upnot used up
Reaction end’s Reaction end’s when there is when there is NO more NO more substrate substrate
Synthesis or Synthesis or Decomposition Decomposition reactionsreactions
Before
After
substrate
enzyme
active site
substrate
Mechanism of enzyme actionMechanism of enzyme action• Each enzyme has an active site• Active site is the place where the substrate
binds with the enzyme
enzyme
Action of enzyme in synthesisAction of enzyme in synthesis
substratesubstrate
enzyme-substrate complex product
enzyme
Action of enzyme in Action of enzyme in decompositiondecomposition
substrate
enzyme-substrate complex
productproduct
Lock and key hypothesisLock and key hypothesis
Enzyme
Substrate
Lock and key hypothesisLock and key hypothesis
SHAPES
DON’T
MATCH
Lock & Key ModelLock & Key Model
One One enzymeenzyme
for every for every substratesubstrate
unique fitunique fit
Enzyme
Substrate
Enzymes are temperature Enzymes are temperature dependent…...dependent…...
0
10
20
30
40
50
60
70
80
90
10 20 37 40
Most work best Most work best at body at body temperaturetemperature
3737ooCC
Denatured at Denatured at high high temperaturestemperaturesInactive at low Inactive at low temperaturetemperature
Temperature oC
Effect of pH on enzyme activityEffect of pH on enzyme activity
Optimum pH : the pH value at which the enzyme has the Optimum pH : the pH value at which the enzyme has the highest activity (fastest rate of reaction)highest activity (fastest rate of reaction)Different enzymes may have different optimum pH’sDifferent enzymes may have different optimum pH’s
pH of substrate higher or lower than optimum pH, it can pH of substrate higher or lower than optimum pH, it can denature the enzyme making it ineffective.denature the enzyme making it ineffective.
Enzyme LabEnzyme LabEnzyme: catalaseEnzyme: catalase
Source: liver, potato, Source: liver, potato, apple etcapple etc
Substrate: HSubstrate: H22OO22
Hydrogen peroxide is Hydrogen peroxide is toxic in cellstoxic in cells
2H2H22OO2 +catalase2 +catalase
22 HH22OO + + O O22
Enzymes end in ‘ase’Enzymes end in ‘ase’
TA TA!TA TA!