1. Enzymes A cell’s toolbox (Ch 6.4)

2. Enzymes are: 1.Proteins 2.Carbohydrates 3.Lipids 4.Nucleic acids 5.Depends on the enzyme

3. progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation energy with catalyst

4. An enzyme is a protein that catalyzes a chemical reaction in living cells. is not consumed in the reaction.

5. Enzyme structure active site substrate enzyme allosteric regulatory site Many enzymes have both active sites and allosteric regulatory sites.

6. 3 Substrates, bonded together, leave enzyme; enzyme ready for new set of substrates. active site of enzyme enzyme substrates 1 Substrates enter active site in a specific orientation. 2 Substrates and active site change shape, promoting reaction between substrates.

7. If enzymes are proteins, which type of molecule contains the instructions for making enzymes? 1.Other proteins 2.DNA 3.Depends on the enzyme

8. Lactase Lactose (milk sugar) is a disaccharide. Lactase breaks lactose down into two monosaccharides, which can be absorbed in the small intestine.

9. Why would the genetic “error” causing lactose tolerance (the ability to drink milk all your life) be selected for in some parts of the world and not in others?

10. Amylase Amylase breaks starch (amylose) apart into monosaccharides Iodine turns black when starch is present. How does the test in this picture demonstrate amylase activity?

11. Pepsin Pepsin is a protease which breaks apart protein chains into smaller chains or single amino acids. If enzymes are proteins, can pepsin digest itself? Hair and feathers are keratin protein. Why aren’t they digestible?

12. If the enzyme amylase were broken down into its monomers by another enzyme, what would those monomers be? What would be the monomers of the enzyme lactase? What about the monomers of the enzyme pepsin? WORKTOGETHERWORKTOGETHER

13. The monomers of enzymes are always: 1.Amino acids 2.Nucleic acids 3.Fatty acids 4.Simple sugars

14. allosteric regulator molecule An allosteric regulator molecule causes the active site to change shape, so the substrate no longer fits. Allosteric inhibition A competitive inhibitor molecule occupies the active site and blocks entry of the substrate. Competitive inhibition Enzyme regulation

15. Regulation controls enzyme pathways. If one enzyme in the chain were missing, could the end product, G, be made? If Product G came from another source, such as from consumed food, what would be its effect on this system?

16. Regulation may be through competitive or non- competitive inhibition.

17. MTHFR gene: methylenetetrahydrofolate reductase enzyme. Located on the p arm of chromosome 1 in humans, this gene codes for an enzyme involved in the methylation of folic acid, a necessary B vitamin. Methylated (folate) and non-methylated (folic acid) forms are found in leafy greens, beans, and whole grains.

18. MTHFR is just one enzyme among many that convert certain nutrients into usable forms and convert waste into non-toxic forms.

19. Lack of the MTHFR enzyme causes buildup of homocysteine and/or folic acid, which can cause damage to the heart, blood vessels, and thyroid over time. Homocysteine is normally converted to glutathione, one of the body’s chief antioxidants. People with a defective MTHFR enzyme lose the protection of this important antioxidant. More information on the MTHFR gene on: http://www.stopthethyroidmadness.co m/mthfr/http://www.stopthethyroidmadness.co m/mthfr/ http://ghr.nlm.nih.gov/gene/MTHFR

20. Which of the following can inhibit enzyme function? 1.Temperature 2.pH 3.The genetic code 4.All of these

21. pH influences enzyme activity enzyme activity acidic pepsin salivary amylase basicpH If you ate a lot of antacids, could that affect your digestion? Why?

22. enzyme activity Enzyme activity increases temperature Maximum activity at optimal temperature. High temperatures distort enzyme structure. Temperature influences enzyme activity What is one reason why high fevers can be dangerous?

23. Recap Enzymes are proteins that catalyze chemical reactions in living systems. Each enzyme does one job, but does that job over and over again. This is referred to as enzyme specificity.