Enzymes and Chemical Reactions

1
Enzymes and Chemical Reactions

• Chapter 4 5

2
Chemical Reactions

• During a chemical reaction, the atoms in the
  reactants get rearranged to form products
• This requires bonds to break and reform
• The breaking and forming bonds involve changes in
  ENERGY!!

3
Energy in Reactions

• Breaking bonds absorbs energy from the
  surroundings, but chemical energy is released
• Forming bonds releases energy to the
  surroundings, but chemical energy is stored
• Chemical reactions either absorb more energy than
  they release, or vice versa

4
Energy-Releasing Reactions

• Often called Exothermic Reactions
• Often occur spontaneously, or with little
  activation energy (energy needed to start the
  reaction)

5
EnergyAbsorbing Reactions

• Often called Endothermic Reactions
• Require an energy source

6
Which is Which??
7
Enzymes are Catalysts

• They speed up chemical reactions by lowering the
  activation energy
• They speed up reactions in cells at normal body
  temperatures

8
Enzyme Structure

• Enzymes are made up of folded
• PROTEIN!!
• The folds created in the forth level of
  organization create ACTIVE SITES for SUBSTRATES
  to bind to
• An enzyme can only catalyze ONE reaction (lock
  key)

9
How Enzymes Work (Fig 5-13 p.104)
10
Enzyme Function

• An enzymes structure and shape is critical to
  its function in the cell
• High temperatures, changes to the pH, or some
  environmental factors can DENATURE protein (or
  unravel it)
• No folds No active sites
• This is why it is important for living things to
  maintain homeostasis