Enzymes

Question 1

Why don’t living things violate the second law of thermodynamics?

Answer 1

All reactions release a small amount of heat energy that contributes to entropy.

Metabolism releases energy.

Ordered structures deteriorate over time and need to be replaced.

Question 2

How does enzyme structure relate to its function?

Answer 2

Enzymes catalyze a specific reaction using a specific substrate. The substrate fits perfectly into the active site of the enzyme.

Question 3

What part of a chemical reaction does an enzyme change?

Answer 3

Enzymes lower the energy barrier of a reaction, with the help of an enzyme it takes less energy for the reaction to take place.

Question 4

What part of a chemical reaction does an enzyme NOT change?

Answer 4

Enzymes have no effect on the free energy of the reactants or products. Can’t change whether the reaction is energy releasing or absorbing.
Don’t alter the chemical equilibrium between the reactants and products.

Question 5

Explain the difference between and endergonic and an exergonic reaction

Answer 5

Endergonic
- releases energy (still requires a little energy input for the reaction to occur)
- spontaneous
- products have LESS free energy than reactants
Exergonic
- absorbs energy
- non-spontaneous
- products have MORE free energy than reactants

Question 6

How does enzyme concentration impact enzyme activity?

Answer 6

More enzymes = increase in enzyme activity/reaction rate.

Question 7

How does substrate concentration impact enzyme activity?

Answer 7

A higher substrate concentration = increase in the rate of reaction. Enzymes can find substrates faster.

Question 8

How does temperature impact enzyme activity?

Answer 8

• each enzyme has an optimal temp for maximum reaction rate
• low temps = slower rate
• high temps can cause denaturation of the enzyme

Question 9

How does pH impact enzyme activity?

Answer 9

• each enzyme has an optimal pH for maximum reaction rate
• low pH = decreased enzyme activity
• high pH levels can cause denaturation of the enzyme

Question 10

How do inhibitors impact enzyme activity? (competitive vs noncompetitive)

Answer 10

General
- certain chemicals inhibit enzyme function
- covalent bonds = irreversible inhibition (toxins/poisons/pesticides/antibiotics)
- weak interactions = reversible inhibition
Competitive
- looks like substrate and binds to the active site stopping the real substrate
- increasing substrate concentrations can overcome the bonds
Noncompetitive
- not bound to the active site
- change the shape of the enzyme making it less effective

Question 11

How do enzyme mutations impact enzyme activity? (Don’t know if this one’s right)

Answer 11

Enzymes are proteins encoded by genes, changes in these genes change amino acid composition.
- can alter substrate specificity (?changes the substrate that fits into the active site?)