3. A single codon is used to signal the beginning of protein synthesis. It is commonly called the START CODON.
Locate the start codon on the chart. What are the three bases of this codon?

Which organelle plays a role in intracellular digestion?

1. an enzyme is considered a(n) because it speeds up a chemical reaction without being used up.2. in a catalyzed reaction, a reactant is often called a(n) . an enzyme is specific because the shape of its matches only particular reactants.4. an enzyme speeds up reactions by lowering the . the between an active site and its substrate often strains bonds and the reaction proceed.6. a( , which is often a vitamin, binds to an enzyme and plays a role in catalysis.7. high temperatures or changes in ph can an enzyme, causing it to lose its shape and biological activity.

True or false 5. carrier proteins have the ability to to change shape and physicially move molecules across the cell membrane. 6. in a facilitated diffusion, the concentration of the molecules to be moved across the cell membrane is higher inside the the cell.