AP BIO Unit 2: Enzymes

1. metabolism: all of the chemical reactions that take place within an organism

1. kinetic

   Nota:

   • energy not in motion
   1. thermal energy: heat

      Nota:

      • the combination of all the movement of the particles in a substance
      1. the energy most difficult to use for doing work
2. potential

   Nota:

   • the energy of motion
   1. chemical energy

      Nota:

      • the potential energy stored within the bonds (chemical makeup) of a substance-- the potential of energy available for release in a chemical reaction

1. 1st law of thermodynamics

   Nota:

   • energy cannot be created or destroyed, only transferred or transformed
2. 2nd law of thermodynamics

   Nota:

   • every energy transfer or transformation increases the entropy of the universe

1. even when the entropy of a certain system is reduced, the overall energy of the universe may be increased due to the production of heat energy

1. ΔG= energy of reactants - energy of products
   1. reactions with a negative ΔG are spontaneous, exergonic
   2. reactions with a positive ΔG are non-spontaneous, endergonic
2. things are naturally moving towards equilibrium?

1. ATP= adenosine TRI phosphate
   1. tends to lose one phosphate group, becomes ADP: adenosine DIphosphate

      Nota:

      • phosphate groups tend to detach because of their negative charge (negatives next to each other--> like charges repel)

1. from ADP?

1. EsubA: activation energy
2. the input energy required for an endergonic reaction to begin

1. structure of enzymes specific to fit enzymes: proteins (3, 4 structures)

   Nota:

   • some enzymes are nucleic acids
2. induced fit

   Nota:

   • when a substrate enters an enzyme's active site, the enzyme's structure changes slightly to grip more tightly around the substrate
3. substrate: what is catalyzed by the enzyme
4. enzyme: a biological catalyst

1. substrate enters an enzyme's active site, it catalyzed

1. effects of temperature and pH
   1. enzyme has an optimal pH and temp where catalysis is most efficient
      1. temp
         1. temp: below optimal point, as temp increases efficiency increases...

            Nota:

            • temp= average heat energy, heat energy= average motion of particles in a substance... more temp=more motion of molecules= substrates will enter enzymes faster
         2. past optimal point, as temp increases efficiency decreases

            Nota:

            • too much heat (too much motion of particles) can cause protein denaturation-- weak bonds holding together a protein's 3°/4° structures (what creates its function) are broken
      2. pH
         1. either more acidic or more basic than optimal point= less efficient

            Nota:

            • can cause protein denaturation... 
            • ex: enzymes in stomach made specifically to function at pH of 2 (pH of stomach acid)... other enzymes would denature in that state
2. cofactors

   Nota:

   • molecules needed for/that aid in an enzyme's catalysis
   1. conenzymes: organic (molecule) cofactors
3. enzyme inhibitors

   Nota:

   • needed for when enough of end product has been catalyzed
   1. competitive inhibitors

      Nota:

      • fit directly into an enzyme's active site, blocking substrates from doing so
   2. noncompetitive inhibitors

      Nota:

      • fit into a site on the enzyme other than the active site, change the enzyme's structure so the enzyme will no longer fit

Nota:

• can be both 

1. allosteric site

   Nota:

   • site on an enzyme where allosteric regulators attach-- not the active site

1. feedback inhibition