Biology 172 Lecture 4

• Shape.
• Because of its specific shape (conformation) the groove region recognizes and binds target molecules on the bacterial walls

an enzyme in saliva that attacks bacteria

Structure both determines and limits function

lowest energy

• Temperature
• Salts (Ions)
• pH

• sickle-cell disease
• Defects in protein folding can have profound consequences

Denaturation is bad. Sometimes can't renature protein

Chaperones

has quaternary structure cap protein must be part of chaperone complex to be fully active structure

Prions cause fatal diseases when misfolded: mad cow ....

the capacity to do work

energy 'stored' in an object

energy of motion, includes motion at the molecular scale (heat)

• mechanical
• chemical
• kinetic (heat) energy

Law of Thermodynamic Motion

reaction characteristics.

• exergonic
• exothermic

• endergonic
• endothermic

change in free energy. ΔG < 0 in a spontaneous reaction; free energy decreases (because some has been used up)

• Difference in potential energy between the products and the reactions
• (-) when heat is released
• (+) when heat is absorbed

• change in entropy = measure of disorder; increases in universe as a whole
• (-) decreases in disorder
• (+) increase in disorder

reactants have more energy than products; spontaneous; energy is released; ΔG < 0

reactants have less energy than products; non-spontaneous; energy is required (consumed); ΔG > 0

Overall ΔG is negative; together, reactions are spontaneous

energy required for reactants to reach the transition state (unstable intermediate) ..... can be overcome by heat or a catalyst

Catalysts work by binding to reactants (weak bonds) and lowering the Ea = energy needed to break / form covalent bonds