1. Molecular Biology

2.  Enzymes are globular proteins that work as catalysts  Catalysts speed up chemical reactions without being altered themselves  Enzymes are often called “biological catalysts” because they are made by living things and speed up biochemical reactions

3.  Substrates are the substances that enzymes convert into products.  A general equation for an enzyme- catalyzed reaction is: substrate enzyme product

4.  Thousands of reactions occur in cells. Nearly all of which need to be catalysed.  Enzymes only catalyze one biochemical reaction.  This is called Enzyme-substrate specificity

5. Enzymes have an active site to which specific substrates bind  Substrate (or substrates) bind to a specific region on the surface of the enzyme called the Active Site  The shape and chemical properties of the substrate and active site match each other

6. Stages of enzyme activity: 1. Substrate(s) binds to the active site. 2. Substrate is converted to products while bound to the active site. 3. The products are released, leaving the site available to catalyse another reaction.

7.  Gerty and Carl Cori Data Analysis Question  p97 in text

8. Enzyme catalysis involves molecular motion and the collision of substances with the active site

9.  A substrate molecule can only bind to the active site if it moves close to it  The coming together of substrate and active site is known as a Collision

10.  Water is in a liquid state… water particles and dissolved particles are in contact with each other and in continual motion  Collisions between substrate and enzyme occur because of these random movements  Successful collisions require the substrate and active site to be correctly aligned

11. Enzymes can be denatured  Enzymes are proteins and, like other proteins, their structure can be irreversibly altered by certain conditions  When the enzyme has been denatured its active site can no longer bind the substrate. What conditions will denature an enzyme?

12. Predict what factors might affect enzyme activity.  Temperature  pH  Substrate concentration

13. Why would temperature affect the rate of enzyme activity?

14. Temperature affects enzyme activity in 2 ways:  Molecules of substrate and enzyme move faster and the chance of collisions increases  Enzyme molecules can become denatured and no longer able to catalyse reactions

15. Why would pH affect the rate of enzyme activity?

16. pH affects enzyme activity  Most enzymes have an optimum pH. This level is not the same for all enzymes.  At higher or lower pH the structure of the enzyme is altered

17. Why would concentration affect the rate of enzyme activity?

18. Substrate concentration affects enzyme activity  Substrate-enzyme collisions take place more frequently with more molecules present  When the active site is occupied it is not available to bind other substrates The rate of increase decreases as concentration increases