1. © 2010 Delmar, Cengage Learning 1 PowerPoint Presentation to Accompany

2. © 2010 Delmar, Cengage Learning 2 Chapter 2 The Chemistry of Life

3. © 2010 Delmar, Cengage Learning 3 Introduction Cells, tissues and organs composed of chemicals Chemical reactions important for function Chemistry is the study of: –Elements, compounds, chemical reactions, molecular structure

4. © 2010 Delmar, Cengage Learning 4 4 Atomic Structure

5. © 2010 Delmar, Cengage Learning 5 Atomic Structure (cont’d.) Atoms –Smallest particles of elements –Maintain all characteristics of element –Nucleus contains protons and neutrons –Electrons orbit nucleus in shells

6. © 2010 Delmar, Cengage Learning 6 6 Elements, Isotopes, Compounds

7. © 2010 Delmar, Cengage Learning 7 Elements, Isotopes, Compounds (cont’d.) Element: atoms contain same numbers of protons and electrons Compound: contains two or more elements Isotope: number of neutrons varies Periodic table of the elements –Arranges elements by increasing atomic number

8. © 2010 Delmar, Cengage Learning 8 Elements, Isotopes, Compounds (cont’d.) Orbital: area where electron is found Energy levels: grouping of orbitals –Represented as concentric circles surrounding nucleus

9. © 2010 Delmar, Cengage Learning 9 9 Bonds and Energy

10. © 2010 Delmar, Cengage Learning 10 Bonds and Energy (cont’d.) Ionic: one atom gains and one atom loses electrons Covalent: atoms share electrons Hydrogen: weak bonds, hold water molecules together Electron donors vs. acceptors vs. carriers Bonds are energy containing

11. © 2010 Delmar, Cengage Learning 11 Bonds and Energy (cont’d.)

12. © 2010 Delmar, Cengage Learning 12 Bonds and Energy (cont’d.)

13. © 2010 Delmar, Cengage Learning 13 © 2010 Delmar, Cengage Learning 13 Common Substances in Living Systems

14. © 2010 Delmar, Cengage Learning 14 Water Most abundant substance in cells Universal solvent Transport of materials Absorbs and reduces heat Protects body structures

15. © 2010 Delmar, Cengage Learning 15 Carbon Dioxide Waste product of cellular respiration Used in photosynthesis to produce usable energy sources Must be removed quickly from cells Carbon in molecules comes from carbon dioxide gas

16. © 2010 Delmar, Cengage Learning 16 Molecular Oxygen Formed from covalent bond of two oxygen atoms Required by all organisms that breathe air Necessary to convert food into ATP Level in atmosphere is 21%

17. © 2010 Delmar, Cengage Learning 17 Ammonia By-product of amino acid breakdown –Amino acids are building blocks of proteins –Amino acids contain nitrogen Converted to urea in the liver

18. © 2010 Delmar, Cengage Learning 18 Mineral Salts Composed of small ions Calcium: muscle contraction and strong bones Phosphate - ATP synthesis Sodium, potassium, and chloride are necessary for muscle contraction and nervous transmission

19. © 2010 Delmar, Cengage Learning 19 Carbohydrates 1:2:1 ratio of carbon, hydrogen and oxygen Five- and six-carbon simple sugars are smallest –Five-carbon: deoxyribose and ribose –Six-carbon: glucose and fructose Functions: energy storage and cell structure

20. © 2010 Delmar, Cengage Learning 20 Lipids Insoluble in water 95% of fats in body are triacylglycerols Saturated fat: fatty acids have single covalent bonds Unsaturated fat: fatty acids have one or more double covalent bonds Functions: energy, insulation and protection

21. © 2010 Delmar, Cengage Learning 21 Proteins Contain carbon, oxygen, hydrogen, nitrogen and sulfur Amino acids are building blocks of proteins Functions: energy and structure Enzymes: protein catalysts for chemical reactions

22. © 2010 Delmar, Cengage Learning 22 Proteins (cont’d.) Structure –Primary: amino acid sequence –Secondary: determined by hydrogen bonds –Tertiary: folding caused by interactions within peptide bonds and sulfur atoms –Quaternary: determined by spatial relationships between units

23. © 2010 Delmar, Cengage Learning 23 Nucleic Acids Deoxyribonucleic acid: genetic material of the cell Ribonucleic acid: protein synthesis –Messenger RNA –Transfer RNA Structure –DNA: double helical chain –RNA: single chain

24. © 2010 Delmar, Cengage Learning 24 Nucleic Acids (cont’d.) Nucleic acids are made up of chains of nucleotides –Nucleotide: nitrogen base, sugar and phosphate group –Nitrogen bases: purines (two) and pyrimidines (three)

25. © 2010 Delmar, Cengage Learning 25 Adenosine Triphosphate Fuel for cell function and maintenance Molecule consists of sugar, adenine, and three phosphates –Energy is stored in the second and third phosphates Breakdown of glucose provides energy to make ATP

26. © 2010 Delmar, Cengage Learning 26 © 2010 Delmar, Cengage Learning 26 Movement of Materials Into and Out of Cells

27. © 2010 Delmar, Cengage Learning 27 Introduction Plasma membrane is selectively permeable –Only selected materials can enter and exit –This is because of chemical structure –Water can enter and exit with ease

28. © 2010 Delmar, Cengage Learning 28 Diffusion Movement of molecules from area of high concentration to low concentration Brownian movement: random collision of diffusing molecules Accelerated by increased temperature O 2 - CO 2 exchange is an example of diffusion

29. © 2010 Delmar, Cengage Learning 29 Osmosis Movement of water through semipermeable membrane from high concentration to low concentration –Isotonic solution: salt concentration is the same outside the cell as inside –Hypotonic solution: salt concentration inside cell is higher than outside cell –Hypertonic solution: salt concentration higher outside the cell than inside

30. © 2010 Delmar, Cengage Learning 30 Osmosis (cont’d.)

31. © 2010 Delmar, Cengage Learning 31 Osmosis (cont’d.) Active transport –Used by cells to obtain sugars, amino acids, larger proteins and fats –Needs energy in the form of ATP –Molecules move from areas of low concentration to areas of high concentration

32. © 2010 Delmar, Cengage Learning 32 © 2010 Delmar, Cengage Learning 32 pH

33. © 2010 Delmar, Cengage Learning 33 pH (cont’d.) Negative logarithm of hydrogen ion concentration Acids: pH values below 7 Bases: pH values above 7 Buffers: help maintain pH levels

34. © 2010 Delmar, Cengage Learning 34 pH (cont’d.)

35. © 2010 Delmar, Cengage Learning 35 Summary Discussed basic chemical concepts such as bonds and energy and how they apply to living systems Discussed specific chemical substances and how they are used in living systems Described three ways that substances move into and out of cells Introduced pH and acids/bases