Transcript Chemical Reactions

Chemical Reactions
And Enzymes
Chemical Reactions
 Processes that change one set of
chemicals into another set of
chemicals
Reactants  Products
(bonds break)
(new bonds form)
Energy in Reactions
 Some reactions release energy
-often spontaneously
 Some reactions absorb energy
-need an energy source
What significance do these energy
changes have for living things?
Activation Energy
 The energy needed to start a reaction
Enzymes
 Some reactions are too slow or
have activation energies that
are too high
 Catalyst – a substance that
speeds up the rate of a
chemical reaction
Enzymes (cont.)
 ENZYMES (proteins) act as biological
catalysts
 They speed up chem.rxns. inside cells
 Lower the activation energy
 They are very specific (catalyze 1
reaction)
 See pg. 51, Figure 2-20
CO2 + H2O  H2CO3
Enzyme Action
 Reactants need enough energy for
bonds to break
 Enzymes provide a site where
reactants can be brought together to
react (active site)
 The site reduces the energy needed
 Substrates -the reactants of
enzyme-catalyzed reactions
(ex. Hexokinase, pg. 52-53)
Enzyme-Substrate complex
Enzyme Activity
 Enzymes can be affected by any
variable that influences a chemical
reaction. Denatured
 examples: pH, temperature change
 Enzymes in human cells work best at
37°C (normal body temp.)
 Lew-port enzymes
 Cells have proteins that help turn
enzymes on and off
 Enzymes are important in:
-regulating chemical pathways
-making materials that cells need
-releasing energy
-transferring information
-form tissues
-fight disease
Hydrolysis of Gelatin
Proteases-enzymes that
break down other proteins
into smaller polypeptides,
amino acids
Isolated from strains of
Bacillus bacteria
-stable at High Temp
-can be genetically engineered
Stable at alkaline pH,
various temps.
Added to laundry
detergents
Can be genetically
engineered
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