Proteins, Enzymes and Nucleic Acids

1. Proteins, Enzymes and Nucleic Acids

2. Structure of a Fat molecule

3. Proteins

4. Protein Functions

5. Proteins-1 • Proteins are made of amino acids • There are 20 different amino acids found in living things • Amino acids have • An amine group • A carboxyl group • Both are attached to the end carbon of a carbon chain

6. Amino Acids

8. Connecting Amino Acids • Dehydration synthesis reaction resulting in a polypeptide

9. Primary Structure of a Protein

10. Secondary Structure of a Protein

11. Tertiary Structure of a Protein

12. Quaternary Structure of a Protein

13. Protein Structure

14. Proteins & Evolutionary Relationships

15. Enzymes

16. Enzyme Characteristics-1 • All enzymes are proteins • Most enzymes are named after their substrate and end in –ase • Enzymes are specific- they work on only one substrate • Enzymes must physically fit together with their substrate- this is what makes them so specific • Enzymes have an active site- this is where the reaction takes place

17. Enzyme reaction

18. Enzyme Characteristics • Enzymes are denatured by high temperatures and by a pH that is too high or too low, relative to their optimal pH • Denatured enzymes lose their shape, so they no longer fit with their substrate

19. How Enzymes Work • Enzymes are catalysts– they speed up reactions • They are not consumed in the reaction • They are not changed in any way at the end of the reaction • They can work in small quantities, because they can be used over and over • They do NOT make reactions occur that would not occur by themselves- they merely speed them up • Lock and Key Hypothesis • Induced Fit Hypothesis

21. Some substances can make enzymes inactive

22. Metabolic Control • Competitive inhibitors- block the substrate from entering active sites • Noncompetitive inhibitors- impede enzymatic reactions by binding to another part of the enzyme which causes the enzyme to change shape, making the active site unreceptive to substrate. • Allosteric regulation- similar to reversible noncompetitive inhibitors. • Allosteric site- a receptor site on the enzyme remote from the active site • Causes inhibition or stimulation of enzyme activity • Enzyme activity changes due to fluctuating concentrations of the regulators.

23. Energy in reactions • Potential energy- • stored energy • Example: Energy in the chemical bonds • Kinetic energy • Energy of motion or work • Example: Energy used to make chemical bonds

24. Endergonic/Exergonic Reactions

25. Activation energy

26. Activation energy of an enzymatic reaction

27. Enzyme Helpers- necessary for catalysis • Cofactors- nonprotein helpers • May be bound tightly to the active site • May bind loosely and reversibly along with the substrate • Some are inorganic: zinc, iron, copper • Coenzyme- protein helper • Most vitamins are coenzymes or • Some vitamins are raw materials from which coenzymes are made

28. Nucleic Acids

29. Nucleic Acid Structure • Nucleic acids are made of Nucleotides • Nucleotides are made of: • A Phosphate group • A Sugar: either ribose or deoxyribose • A Base: A, T, G, C, U • A= adenine • T= thymine • G= guanine • C= cytosine • U= uracil

32. Nucleic Acids- DNA & RNA • There are only two nucleic acids: • DNA: deoxyribonucleic acid • RNA: ribonucleic acid • Functions: control cell function and heredity • DNA makes RNA • RNA makes proteins

33. Comparison of DNA and RNA Structure

34. Structure of one strand of a DNA molecule

35. Structure of DNA