Energy

1
Energy Metabolism/Enzymes
2
Energy
Potential Energy
Kinetic Energy
1st Law of Thermodynamics (Conservation of
Energy) energy cannot be created nor destroyed,
just converted from one form to another
2nd Law of Thermodynamics systems tend toward
increasing entropy until equilibrium is reached
3
The Second Law of Thermodynamics
Less energy
More energy
Equilibrium
The molecules in the ice become more
disordered (entropy has increased)
4
Metabolism

Metabolic Pathways
- mediated by ENZYMES
Enzymes

Reactants (substrates)
End Products
5
Transformation of Energy

• Chemical Reactions involve breaking and forming
• chemical bonds
• Energy is absorbed or released in the process

6
Energy for Living Things

• ATP is the energy currency of the cell.

• ATP is comprised of a sugar, a base, and
• 3 phosphate groups

• ATP works by transferring a phosphate group
  (PO4-)
• to another molecule and activating that
  molecule

7
Enzyme structure
Primary - number, order of amino acids
Secondary - coil, pleated sheet
Tertiary - globular, 3-dimensional
Quarternary - multiple units
8
Enzymes...

9
Enzymes speed up chemical reactions by lowering
the activation energy
Activation energy
10
Without Enzyme...
With Enzyme...
11
Induced-Fit Model for enzyme activity (Lock and
Key)
Substrate binds to the ACTIVE SITE of the enzyme
1
Enzyme
Substrate
Substrates fit most precisely in the active site
when they have reached an activated TRANSITION
STATE
2
Transition State
Product is released and enzyme may receive
additional substrate
3
Product
12
The Environment can Influence Enzyme Activity
1. Temperature - Enzymes work
at an optimum temperature
ACTIVITY
TEMPERATURE
2. pH - Enzymes work at an optimum
pH
ACTIVITY
0
14
pH
13
Study Objectives 1. Define Energy. Explain the
difference between potential energy and kinetic
energy. 2. Explain the first and second Laws of
Thermodynamics. 3. Define entropy. 4. Define
metabolism. 5. Explain the roles of reactants,
products, and enzymes in metabolic pathways. 6.
What is the usable form of energy for living
things? 7. Describe the structure of ATP and how
it stores energy. 8. Describe the structure of an
enzyme. 9. Define catalyst. 10. What is meant
by enzyme specificity? 11. Explain how enzymes
speed up chemical reactions. 12. Define
activation energy. 13. Explain the induced fit
(lock and key) model of enzyme activity. Include
the terms active site and transition
state in your explanation. 14. Describe 2
factors that can influence enzyme activity. What
is meant by optimum temperature and
optimum pH? Know how to illustrate these
relationships on a graph. 15. Explain what
happens to enzymes at very high temperatures.