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 GelatinProteases-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

http://http://homepage.smc.edu/wissmann_paul/anatomy2textbook/AAcidsProteins.htmlhomepage.smc.edu/wissmann_paul/anatomy2textbook/AAcidsProteins.html