Unit 1 The Chemistry of Life

1. Unit 1 The Chemistry of Life

2. §1.1 Water Water is a polar, covalent, inorganic molecule Due to unequal sharing of electrons between oxygen and hydrogen, each atom has a partial charge These partial charges are called dipoles The weak forces that attract and hold molecules with opposite dipoles together are called hydrogenbonds

3. Dipoles Negative dipoles are those with a partial negative charge, like oxygen in water Positive dipoles are those with a partial positive charge, like hydrogen in water

4. The cohesionamong water molecules allows water to travel in tubes such as roots, up to the leaves of plants and in blood vessels • cohesion also accounts for surface tension

5. Properties of Water Excellent solvent High specificheatcapacitywhich is how some animals maintain a body temperature that is life sustaining Great Lubricant Transparent Greatest densityis at 4oC

6. Molecules that are ionically bonded together will dissociatein water and the water will transport the resulting ions ex. NaCl(aq) -> Na+(aq) + Cl-(aq)

7. §1.2 Acids, Bases, Buffers and pH Water molecules self-ionize to form hydrogen and hydroxide ions A strong acid is HCl because it readily dissociates, producing free hydrogen and chlorine ions NaOH is a strong basebecause it readily dissociates, producing free hydroxide and sodium ions Bases have a neutralizing effect on acids

8. Reactions H2O - > H+ + OH- HCl - > H+ + Cl- NaOH - > Na+ + OH- Na+ + OH- + H+ + Cl- - > NaCl + H2O

9. pH pH is a measure of the amount of free hydrogen ions in a system pH = -log[H+] Range from 1 to 14 (in general) When [H+] = [OH-], the pH = 7, which is neutral Above 7 is basic and below is acidic pH in the blood varies from 7.35-7.38 whereas pH in the stomach is about 2.5

10. Buffers To prevent significant changes in pH and to maintain homeostasis, organisms have buffers These are molecules that can either pick up or release hydrogen ions Bicarbonate is a common buffer (HCO3- )

11. §1.3 Macromolecules When small molecules are combined, water is often a product, a reaction known as dehydrationsynthesis The reverse, involving water as a reactant is called hydrolysis These are called enzymatic reactions because they require an enzyme to react

13. Macromolecules are made from unitmolecules, or monomers If the macromolecule is a sequence of many monomers, it is called a polymer

14. Four Major Macromolecules Carbohydrates Lipids Proteins Nucleic acids All but lipids are considered polymers Lipids do not really form a polymer because the number of unit molecules that can join together to form a macromolecule is limited

15. Review Which adjective does NOT apply to water? Bent Polar Organic Covalent

16. Which adjective does NOT apply to water? Bent Polar Organic Covalent

17. The water in an organism’s body helps reactions occur transport molecules maintain body temperature all of the above

18. The water in an organism’s body helps reactions occur transport molecules maintain body temperature all of the above

19. Which of the following is closest to the pH of blood? 4.8 6.7 7.3 10.8

20. Which of the following is closest to the pH of blood? 4.8 6.7 7.3 10.8

21. Which of the following BEST describes an acidic solution? Lots of H+ present Lots of OH- present More H+ than OH- present More OH- than H+ present

22. Which of the following BEST describes an acidic solution? Lots of H+ present Lots of OH- present More H+ than OH- present More OH- than H+ present

23. Buffers that keep the pH at 8.3 MOST LIKELY release H+ bond with H+ bond with OH- dissociate to release both H+ and OH-

24. Buffers that keep the pH from rising above 8.3 MOST LIKELY release H+ bond with H+ bond with OH- dissociate to release both H+ and OH-

25. An example of the synthesis of a polymer could be amino acids taking up excess hydrogen ions joining monosaccharides and removing water forming water by combining an acid and a base adding water to break a polypeptide into amino acids

26. An example of the synthesis of a polymer could be amino acids taking up excess hydrogen ions joining monosaccharides and removing water forming water by combining an acid and a base adding water to break a polypeptide into amino acids

27. §1.4 Carbohydrates Carbohydratesare hydrates of carbon The empiricalformulaof a carbohydrate is CH2O (i.e. C + H2O = CH2O) Either sugars or polymers of sugars Glucoseis a very common simplesugar (a monosaccharidethat has a molecular formula of C6H12O6) Glucose undergoes dehydration synthesis to become the double sugar maltose(or a disaccharide) Continued DS will result in larger molecules called oligosaccharidesand finally polysaccharides

28. Empirical Formula An empirical formula is the simplest form of it’s molecular formula Think of the empirical formula as the smallest ratio of all of the elements present in the molecular formula For example, take C6H12O6 The empirical formula is CH2O

29. Other Types of Simple Sugars Glucose, fructose, and galactoseall have the same chemical formula, i.e. Isomers, (C6H12O6) They differ only in the arrangement of their atoms Riboseis another simple sugar (C5H10O5)

30. Common Disaccharides Table sugar, or sucrose (glucose + fructose) Lactose, the sugar in milk (glucose + galactose)

31. Polysaccharides Differ by the way the monosaccharides are bonded together Starch is a linear polymer that spirals to form a helix that sometimes branches

32. Glycogen is highly branched, in comparison to starch Cellulose is a linear sequence of glucose molecules

33. Glucose The product of photosynthesis Plants make it, metabolize it for energy, store it as a starch and convert it into cellulose to build new cell walls for growth Our food contains carbohydrates Starches and disaccharides are digested into glucose molecules, which are transported by our circulatory system to body cells where they are oxidized in the mitochondria during the process of cellularrespiration

34. Excess glucose is stored in the liver in the form of glycogen Cellulose is sometimes referred to as dietary fiber, as people are unable to digest it in food, and serves a useful purpose in the production of feces

35. §1.5 Lipids A second group of biochemicals is lipids Lipids will not mix freely with polar solvents like water We eat them as food, our bodies produce them and they are the second most important energy molecule for us They unfortunately tend to be stored as adipose (fat) cells Include fattyacids, neutral fats, oils, steroids like cholesterol and some hormones, waxes and other specialized molecules

36. Fatty Acids Fatty acids are non-polar chains of carbon and hydrogen with a carboxylic acid end Some fatty acids are saturated (without double bonds) while others are unsaturated(with double bonds and therefore less hydrogen) In general, the fatty acids produced by animal tissues are more saturated and tend to be solid at room temperature Those produced by plant tissues are unsaturated and tend to be liquid, like vegetable oil (good for body)

38. Neutral Fats Produced by the DS of one or more fatty acids with glycerol, an alcohol Many types are possible due to the number and variety of fatty acids and the three different bonding locations on glycerol

39. A monoglyceride has one fatty acid combined with a glycerol A diglyceride has two fatty acids and a glycerol A triglyceride has three and a glycerol

40. Specialized Variations Lipids that are biologically important including phospholipids, steroids and waxes Phospholipids are a variation of a tryglyceride where one of the fatty acids is replaced with a phosphate and nitrogen containing group

41. Phospholipids The replacement of a phosphate and nitrogen containing group creates a polar region on an otherwise nonpolar molecule Consequently phospholipids can mix with both polar and nonpolar material They are an integral component of all cell membranes

42. Steroids Nonpolar ring structures Sex hormones (estrogen and testosterone) Cholesterol, which helps maintain the integrity of cell membranes Waxes are combinations of fatty acids and an alcohol larger than glycerol

44. Review Which of the following is NOT a polysacchraide? Starch Glycerol Cellulose Glycogen

45. Which of the following is NOT a polysacchraide? Starch Glycerol Cellulose Glycogen

46. Which biochemical is a component of cell membranes? Hormones Triglycerides Disaccharides Phospholipids

47. Which biochemical is a component of cell membranes? Hormones Triglycerides Disaccharides Phospholipids

48. Which of the following molecules is the most highly branched? Starch Maltose Glucose Glycogen

49. Which of the following molecules is the most highly branched? Starch Maltose Glucose Glycogen

50. What is a phospholipid composed of? Cholesterol, glycerol, fatty acids Phosphate group, cholesterol protein Fatty acids, phosphate group, glycerol Glycerol, amino acids, phosphate group