Chapter 4 Lecture Outline

1. Chapter 4Lecture Outline Chemical Building Blocks © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

2. Atoms and Molecules Big fleas have little fleas Upon their backs to bite ‘em Little fleas have littler fleas And so ad infinitum © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

3. Atoms and Elements • Physical world composed of 92 elements • Simplest building blocks • Atom - smallest unit of an element © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

4. Periodic Table of the Elements © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

5. Atomic Components • Atoms are composed of 3 subatomic particles • Electrons – negatively charged • Protons – positively charged • Neutrons – no charge (neutral) • Protons & neutrons are contained in the nucleus • Electrons orbit the nucleus • Gain or loss of an electron: ion © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

6. Atomic and Mass Numbers • Atomic Number: Number of Protons • Determines the element’s properties • Mass Number: Number of Protons + Number of Neutrons • Isotopes: different numbers of neutrons • Unstable isotopes: Radioisotopes © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

7. Covalent Bonds • Electrons are held in shells • Atoms are stable when its shells are filled • Atoms share electrons to fill these shells © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

8. Covalent Bonds – Examples of Molecules © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

9. Noncovalent Bonds • Link molecules together (intermolecular) • Much weaker than covalent • Much more prevalent • Hydrogen bonds: very common in biology • Attraction between partial charges • Hold biological molecules together • Ionic bonds: form between charged particles (Ions) © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

10. Hydrogen and Ionic Bonds Ionic bonds form between Na+ and Cl- Hydrogen bonds form between water molecules © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

11. Hydrogen bonds: Water © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

12. Hydrogen bonds are like Velcro © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

13. Velcro and H Bonds form weak, temporary bonds • Each Velcro link is weak • Each H bond is weak • Many Velcros are strong • Many H bonds are strong © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

14. Ionic Bonds: Salt crystals • Form between atoms of opposite charge • Weak in aqueous conditions • Strong in dry conditions • Ions are bound by polar water molecules © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

15. Water molecules break up salt © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

16. Rearranging Atoms in Molecules • Chemical reactions: • Breaking covalent bonds • Forming new bonds • Require energy 3 H2 + N2 2 NH3 © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

17. Acids and Bases • Acid: releases H+ in water HCl + H2O  Cl- + H30+ • Base: accepts H+ from water NH3 + H20 NH4+ + OH- © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

18. pH • A measure of H+ concentration • The scale pH is from 0 to 14 • Scale is 10X • More than 7 is basic • Less than 7 is acidic Coke © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

19. Buffers Control pH • Buffer - weak acid or base • Maintains pH within very narrow limits • Accepts H+ when pH is low • Releases H+ when pH is high AH + H2O  A- + H3O © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

20. STOP HERE • To be Continued……….. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

21. Carbon-based Molecules • Biomolecules are mainly C and H • Carbon chains can be very long • O, S, P, and N are also present • These comprise functional groups • Functional groups allow molecules to interact • Biomolecules are combined to form polymers © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

22. Carbohydrates Sugar Starch Cellulose Fats Lipids Fatty acids Cell membranes Proteins Amino acids Collagen Fibrin Nucleic Acids DNA RNA What are Biological Molecules? © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

23. Carbohydrates: Simple Sugars • Sugars are carbohydrate monomers • Used to store and release energy • Glucose plays a key role • Dehydration synthesis: combining sugars • What other kinds of sugars to you know? © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

24. Other kinds of sugars: Glucose Fructose Lactose © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

25. Carbohydrates – Complex Sugars • Monosaccharides – one sugar molecule • Disaccharides – two sugar molecules • Oligosaccharides – a few sugar molecules • Polysaccharides – many sugar molecules Don’t ask me to define “few” or “many” © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

26. Branched Chain Polysaccharide Very complex Indeed! © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

27. Carbohydrates: Polymers Cellulose: Structure Starch: Energy storage © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

28. Nucleic Acids: Nucleotides • Made of three parts • Sugar (ribose), phosphate, and nitrogen base • Monomers can be used as “energy currency” ATP Energy Energy © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

29. Nucleic Acids: DNA and RNA • Information storage molecules Phosphate Group Bases Nucleotide Adenine (A) Thymine (T) Sugars Ribose Guanine (G) Cytosine (C) Uracil (C) Deoxyribose © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

30. Proteins: Amino Acids • There are 20 amino acids • They all have: • Central C • Amino group (nitrogen) • Carboxyl Group • R group • Each amino acid differs in its R group • Amino acids link together to form proteins © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

31. Kinds of R Groups © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

32. Proteins: Polypeptides • Amino acids are covalently linked • Peptide bonds C to N • Primary structure: sequence of amino acids • This determines folding of the protein NOT!! © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

33. Proteins: 3D Structure Telephone cord © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

34. Lipids: Fatty Acids Charged polar end • Long hydrocarbon chains • Very hydrophobic • Oil and water don’t mix • Used for energy storage • Very high energy • Long-term storage Lipid tail end © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

35. Lipids: Structure • Fats are bonded to glycerol with phosphate • Produces hydrophobic and hydrophilic parts • Forms a bilayer in water • Structure of cell membrane Lipid bilayer: © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

36. Concept Quiz What types of intermolecular bonds are formed between biological molecules and hold them together? • Hydrogen bonds • Covalent bonds • Ionic bonds • All of the above • A & C © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

37. Concept Quiz What determines the folding pattern of a peptide into a completed protein? • The amino acid sequence (primary structure) • The source of the amino acids • The absorption of light • The size of the ribosomes used © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

38. Concept Quiz _________ bonds are the strongest bonds formed between molecules. • Hydrogen • Covalent • Ionic • Non-polar © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

39. Concept Quiz The main difference between the 20 amino acids is the • central carbon. • amine group. • acid group. • side chain. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e

40. Process Animation 4.1Formation of Covalent Bonds Macintosh Windows © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e