1. Chemical Reactions Important to Physiology- Break Down, Build Up
Decomposition reaction (catabolism):
AB A + B
Synthesis reaction (anabolism):
A + B AB
Exchange reaction (reversible):
AB A + B
Catabolism-break down polysaccharides to monomers (glucose) for absorption into bloodstream
Anabolism-build proteins from monomers (amino acids) for growth and development
Exchange – carry oxygen in blood stream on hemoglobin and release at tissue level

2. Energy In, Energy Out Exergonic reactions: Endergonic reactions:
produce more energy than they use
Example: Cellular respiration
Endergonic reactions:
use more energy than they produce
Example: hydrolytic reactions require energy to use water molecules to break apart macromolecules during digestion
Most chemical reactions that sustain life cannot occur unless the right enzymes are present

3. Materials in Reactions
Reactants:
materials going into a reaction
Products:
materials coming out of a reaction
Enzymes:
proteins that lower the activation energy of a reaction

4. Enzymes control metabolism by lowering Activation Energy
Chemical reactions in cells cannot start without help
Activation energy gets a reaction started
Figure 2–7

5. Lower the activation energy, increase the speed of a reaction (millions of reactions per minute!)

6. Shape and Function Protein function is based on shape
Shape is based on sequence of amino acids
Denaturation:
loss of shape and function due to heat or pH

7. Enzyme Names
Often named for the reaction they catalyze; usually end in -ase
(e.g., hydrolases, oxidases)

8. Enzymes Enzymes are catalysts: Specificity: Regulation:
proteins that lower the activation energy of a chemical reaction
are not changed or used up in the reaction
Specificity:
one enzyme catalyzes one reaction
Regulation:
the ability to turn off and on

9. How Enzymes Work
Figure 2–21

10. How Enzymes Work Substrates: Active site: Product
reactants in enzymatic reactions
Active site:
a location on an enzyme that fits a particular substrate
Product
the end result of the enzymatic reaction

11. ADP and ATP (modified RNA nucleotides)
adenosine diphosphate (ADP):
2 phosphate groups
di = 2
adenosine triphosphate (ATP):
3 phosphate groups
tri = 3

12. Phosphorylation
• Adding a phosphate group to ADP with a high-energy bond to form the high-energy compound ATP
ATPase: (ATP synthase)
the enzyme that catalyzes phophorylation

13. The Energy Molecule Chemical energy stored in phosphate bonds
Figure 2–24