Chemical reactions

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Chemical reactions

• Everything that happens in an organism - growth,
  its interaction with the environment,
  reproduction, and movement- is based on chemical
  reactions

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Chemical Reactions

• Changes one set of chemicals into another
• Reactants - elements that enter into chem rxns
• Products - elements that are produced by chem
  rxns
• Chemical reactions involve breaking bonds in
  reactants forming new bonds in products

3
Energy reactions

• Reactions involve energy changes
• Chem rxns that release energy-spontaneous.
• Chem rxns that absorb energy wont occur without
  a source of energy

4
Energy

• Living things need energy to stay alive
• Plants-trap/store energy from sun
• Animals-get energy when they consume plants/other
  animals
• Humans release energy needed to grow tall, to
  breathe, to think, and even to dream thru
  chemical reactions that occur when we digest food
• Activation energy- amount of energy needed to
  start a reaction. Ex, cellulose.

5
Catalysts

• Some reactions that make life possible are too
  slow or have really high activation energies to
  make them practical for our bodies
• These reactions are made possible by catalysts
• Catalyst- substance that speeds ? a chem rxn
• They lower a reactions activation energy

6
Enzymes

• Catalyst enzymes
• Enzymes- biological catalysts that speed up
  reactions that take place in cells by ?
  activation energy, thus the reaction is completed
  quickly
• Play essential roles in regulating chem pathways,
  making materials cells need, releasing energy,
  transferring info
• Enzymes very specific, catalyzing 1 reaction
• They are not used up in a reaction, once done
  they are free to start another process
• Enzymes have an (-ase) ending in the name
  sucrase breaks down sucrose, proteases breakdown
  proteins, lipases breakdown lipids, DNA
  polymerase builds DNA

Enzyme
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Enzyme-Substrate Complex
Forms a complex with a substrate like a key that
unlocks the energy at the active site, required
for the reaction
This increases the speed of the reaction

enzyme
Key-substrate
Key-substrate
Enzyme activity affected by change in temp and
pH Enzymes that stop working- denatured
Active site
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