Which of the following biomolecules consists of monomers of amino acids:

1
Multiple Choice

• Which of the following biomolecules consists of
  monomers of amino acids
• A) carbohydrates B) Proteins C) Nucleic acids
• Which of the following biomolecules consists of
  monomers of nucleotides
• A) carbohydrates B) Proteins C) Nucleic acids
• Which of the following biomolecules is not used
  to store biological information
• A) carbohydrates B) Proteins C) Nucleic acids

2
LEQ How do enzymes help cells perform chemical
reactions?

• Reading 2.5, 12.3 Unit 2 Test mon
• Activator Reaction Acrostic
• Term, phrase, idea using R-E-A-C-T-I-O-N
• Key terms bond energy, activation energy,
  enzyme,

3
Bonds break and form during chemical reactions.

• Chemical reactions change chemicals into
  different ones
• breaking old bonds
• forming new bonds

O2 C6H12O6 CO2 H2O
Reactants Products

• Bond energy
• Energy is added to break bonds.
• released when bonds form.

4
Organisms require energy for a cell to maintain
homeostasis.

• Products must be generated

• Reversible reactions can reach equilibrium -
  generally fatal to cells (no way to generate
  products)

CO2 H2O H2CO3
5
Chemical reactions release or absorb energy.

• Activation energy needs to be absorbed to start a
  chemical reaction.
• Significantly delay rate of reaction

6

• Exothermic reactions release more energy than
  they absorb.

• Products have lower bond energies

7

• Endothermic reactions absorb more energy than
  they release.

• Products have higher bond energies.

8
A catalyst lowers activation energy.

• Catalysts are substances that speed up chemical
  reactions.
• decrease activation energy increase reaction rate

9
Enzymes are proteins that catalyze chemical
reactions without being consumed.

• Enzyme terms
• Substrate
• Reactant(s)
• Active site
• Binds substrates
• Substrate specific

10

• The lock-and-key model helps illustrate how
  enzymes function.

11
Questions

• Chemical reactions tend to reach equilibrium when
  they are left to proceed on their own. Why is
  this dangerous for a cell (Hint how will this
  affect the production of biomolecules)?
• Biological catalysts are essential for cells to
  function as systems. Do you think cells could
  produce polymers by using uncatalyzed reactions?
  Why or why not?
• Consider exothermic and endothermic reactions.
  How do cells find the energy to perform an
  endothermic reaction?

12
Summary

• How is the structure of an enzymes binding site
  related to its function?
• When a chemical reaction reaches equilibrium
  describe what is happening to reactants and
  products.
• What prevents a chemical reaction from occurring
  spontaneously?
• Speculate why has evolution produced nothing but
  cells that specialize in catalyzed chemical
  reactions?
• How do catalyzed chemical reactions aid in
  homeostasis?
• How can exothermic and endothermic reactions be
  considered a system?
• The process below is exothermic. What must be
  true about the bond energies of the reactants and
  the products? Explain
• 6O2 C6H12O6 ? 6CO2 6H2O

13
Answers

• Catalysts reduce the activation energy required
  to start a chemical reaction - easier to
  rearrange chemical bonds to form product.
• Enzymes bring substrates close together so that
  they can react and slightly alter the bonds
  within the substrates by changing the shapes of
  the molecules (lowers the activation energy
  barrier).
• Endothermic reactions absorb energy and their
  products have higher bond energy (energy goes
  into bond formation). Exothermic reactions
  release energy and their products have lower bond
  energy (energy leaves the reaction site when
  bonds break).
• Bond energies must be higher in reactants than
  those of products energy is released