1. Unit 3 The Chemistry of Living Things (“Biochemistry”) 1

2. Slide 2.1 Atoms “atom” means “can’t be cut” – coined by Greeks 2500 years ago. The atom is the smallest functional unit of an element. Atoms are made of: (see next slide)

3. Atoms are made of Protons: positive charge, in nucleus, are heavy, “p + ” Neutrons: no charge, in nucleus, are heavy, “n 0 ” Electrons: negative charge, outside nucleus “electron cloud”, very light (1/1840 of a proton or neutron), “e - ”

4. Only copy red diagram in upper left. No caption needed.

5. Charges in an Atom The + charge on a proton is equal to the - charge on an electron. Atoms are neutral (have no overall charge) Therefore, the # of protons = # electrons in an atom.

6. Slide 2.2 Atomic number – determines the identity of the atom. – It tells us the number of protons in the atom. – It also tells us the number of electrons (b/c an atom is neutral in charge.) – Ex: atomic number of carbon, C = 6 – Question: how many protons? How many electrons? How many neutrons? 6

7. Atomic Number 7 Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element. Element # of protons Atomic # (Z) Carbon66 Phosphorus1515 Gold7979

8. Isotopes The number of neutrons can vary from atom to atom in an element. Atoms of the same element w/different #s of neutrons are called ISOTOPES. In order to know how many neutrons in an atom you must be told. The mass number tells you how much mass the atom has. – Since p + and n 0 are the heavy parts, – mass # = # of p + ’s + n 0 ’s. 8

9. Writing atomic symbols for isotopes 9 B 5 11 Atomic # Mass # Symbol for element

10. Naming Isotopes  The atom in the prior slide can be called “boron-11” 10 Name of element Mass #

11. Mass Number 11 Mass number is the number of protons and neutrons in the nucleus of an isotope: Mass # = p + + n 0 Nuclide p+p+p+p+ n0n0n0n0 e-e-e-e- Mass # Oxygen - 10 -3342 - 31 - 3115 8 8 18 Arsenic 7533 75 Phosphorus 15 31 16

12. QUESTION: If the mass number of a carbon atom is 14, How many protons? How many electrons? How many neutrons? LET’S PRACTICE! – Whiteboard – Marker – Paper towel 12

13. Atomic Mass Units (don’t copy) Atoms are weighed in a.m.u. 1 a.m.u. is based on the mass of a Carbon-12 atom. – it has 6 p+ and 6 n 0, – 1 a.m.u = 1/12 the mass of a carbon-12 atom. 13

14. ELECTRONS Electrons are in constant motion around the nucleus. e-s in the highest occupied level are called valence e-s. 14

15. IONS When they do this, they get a charge. – If you lose an electron, the ion has a ___ charge – If you gain an electron, the ion has a ___ charge 15

16. ATOM v. ION ATOM – has no charge ION- has a charge (b/c e-s have been lost OR gained) 16

17. Slide 2.3. BONDING: (Definition) atoms combining to form molecules It occurs when valence electrons rearrange themselves – There are 2 ways to get the e-’s you need. Sharing electrons (COVALENT BONDING) Gain/lose electrons (IONIC BONDING) 17

18. 18 COVALENT BONDS

19. Formation of SALT, NaCl IONIC BONDS 19

20. The Most Common Elements in Living Things Carbon Hydrogen Oxygen Nitrogen Phosphorus Sulfur 20

21. Elements of Living Organisms ( DON’T COPY) 21 Table 2.2 Slide 2.5

22. Life Depends on Water Water molecules are polar (they have slight electrical charges, like little magnets) o Biological solvent-ex: K+ for muscle contraction o Hydrogen bonds make it expand when frozen (animals in lakes can survive winter) o Water is liquid at body temperature o Water can absorb and hold heat energy o Water helps regulate body temperature 22 Slide 2.6 IMPORTANT FACTS ABOUT WATER

23. Properties of Water (b/c of hydrogen bonding) 1. Cohesion- attraction between molecules of the same substance. (water-water attraction) Examples – Drops of water – Surface tension (Fig 2-8 p 41 of text) 23

24. Properties of Water (b/c of hydrogen bonding) 2. Adhesion-attraction btwn molecules of different substances (water-other substance attraction) Examples – Capillary action-water drawn up a tube – “Meniscus”= the curve shape water has when in a tube 24

25. Water forms Important Mixtures Solutions (DEFINITION) when a substance dissolves in water Ex: Salt-water. NaCl is pulled apart into IONS by the water. 25

26. Water forms Important Mixtures (cont.) Suspensions Material does NOT dissolve, but separates into small pieces that remain floating Ex: blood w/red blood cells 26

27. ACIDS & BASES Water can form ions too! H 2 O  H + + OH - When by itself, water makes equal amounts of H + + OH - 27

28. ACIDS & BASES (cont.) Some things cause water to release many H+ ions. These are acids. Some things cause water to release many OH- ions. These are bases.bases pH is a measure of the H + concentration in a solution. 28

29. Figure 2.10 Slide 2.10 The pH Scale 29

30. BUFFERS (DON’T WRITE THIS) Remember homeostasis? WRITE THIS: All living things need to maintain a stable pH. – Humans need a pH between 6.5 & 7.5 – Otherwise, chemical reactions get messed up. They do this through buffers: weak acids or bases that prevent sharp, sudden changes in pH – Ex: ______ for an upset stomach. It absorbs extra H+ ions. 30

31. (Section 3): Carbon “Organic” Compounds Why is carbon so special? Carbon has 4 valence electrons, Allows it to bond to many other things at once. Pix of organic compounds important to living things Pix of organic compounds important to living things 31

32. Section 3: Carbon (Organic) Compounds of Living Organisms Is 18% of human body by weight Forms four covalent bonds Can form single or double bonds Can build micro- or macromolecules (big chains) Slide 2.11 Carbon is the building block of living things:

33. Figure 2.12 Slide 2.12 Carbon Can Bond in Many Ways Don’t Copy Diagrams. Leave room for 2-3 sentences. 33

34. Figure 2.14 Slide 2.15 1: Carbohydrates MADE OF: C, H, O (don’t copy diagrams) FUNCTION: energy & structure

35. 1. Sugars: short chains of – Monosaccharides- 1 sugar ring Ex: glucose, galactose – Disaccharides-2 attached sugar rings Ex: sucrose, fructose, lactose 2. Polysaccharides: thousands of monosaccharides joined in chains and branches – Starch: made in plants; stores energy – Glycogen: made in animals; stores energy – Cellulose: undigestible polysaccharide made in plants for structural support Slide 2.16 Types of Carbohydrates

36. Lipids: Insoluble in Water TYPES OF LIPIDS Triglycerides: energy storage molecules – Fatty acids: saturated and unsaturated Phospholipids: cell membranes Steroids: carbon-based ring structures – Cholesterol: used in making estrogen and testosterone 36 Slide 2.17 2: Lipids Made of: C,H,(O) Function: energy storage, waterproof coverings

37. Proteins: Complex Structures Contructed of Amino Acids Made of: C,H, O, N Function: building materials, enzymes Structure – Made of monomers called amino acids – The instructions for building proteins are in DNA Slide 2.18 Proteins

38. Copy only bottom diagram & leave room for examples

39. Don’t copy, but Leave room for examples

40. Hemoglobin (4 protein strands held together) Don’t copy, but Leave room for examples

41. Enzyme Function Enzymes: – are proteins – function as catalysts (something that speeds up chem rxns) – facilitate chemical reactions Lower the activation energy (energy required to start a rxn.) The function of an enzyme is dependent on: – temperature – pH – ion concentration – presence of inhibitors 41 Slide 2.19

42. Enzyme Action 42

43. Structure and Function of Nucleic Acids Functions – Store genetic information – Provide information used in making proteins Structure – Nucleotides consist of a phosphate group, a sugar, and a nitrogenous base – DNA structure is a double helix: two associated strands of nucleic acids – RNA is a single-stranded molecule 43 Slide 2.20

44. Structure of DNA and RNA DNA: double-stranded – Sugar: deoxyribose – Nitrogenous bases: adenine, thymine, cytosine, guanine – Pairing: adenine-thymine and cytosine-guanine RNA: single-stranded – Sugar: ribose – Nitrogenous bases: adenine, uracil, cytosine, guanine – Pairing: adenine-uracil, cytosine-guanine 44 Slide 2.21 Nucleic Acids.

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46. RNA structure Don’t copy 46

47. Figure 2.25 Slide 2.22 Copyright © 2001 Benjamin Cummings, an imprint of Addison Wesley Longman, Inc. Structure and Function of Adenosine Triphosphate (ATP) Copy diagram on right,