UNIT 1: Structure and Function (Biochemistry) Chapter 2: Chemistry of life

1. UNIT 1: Structure and Function (Biochemistry) Chapter 2: Chemistry of life

2. UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of Life I. Atoms, Ions, and Molecules (2.1) A. Living things consist of atoms of different elements

3. 1. An atomis the smallest basic unit of matter 2. An elementis one type of atom 3. An atom has a nucleus and electrons

4. a. The nucleushas protonsand neutrons b. Electronsare in energy levels outside the nucleus

5. 4. A compoundis made of atoms of different elements bonded together a. Water (H20) b. Carbon dioxide (CO2) c. Many other carbon-based compounds in living things.

6. B. Ionsform when atoms gain or loseelectrons 1. An ion is an atom that has gained or lost one or more electrons a. Positive ions -lost electron(s) b. Negative ions -gain electron(s) 2. Ionic bonds form between oppositely charged ions

7. C. Atoms share electrons in ____________bonds

8. 1. A covalent bond forms when atoms sharea pair of electrons

9. 2. A moleculeis two or more atoms held together by covalent bonds

10. II. Properties of Water A. Life depends on hydrogen bonds in water 1. Water is a polar molecule a. Polar molecules have slightly charged regions

12.  b. Nonpolarmolecules do not have charged regions

13. c. Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.

14. 2. Hydrogen bonds are responsible for three important properties of water. a. High specific heat-the heat in calories required to raise the temperature of one gram of a substance one degree Celsius

15. b. Cohesion-attraction between molecules of the same substance (because of hydrogen bonds, water is very cohesive)

16. c. Adhesion-attraction between different substances. Adhesion between water and other charged or polar substances very important force. (responsible for capillary action)

17. B. Many compounds dissolve in water 1. A solutionis formed when one substance dissolves in another a. A solution is a homogeneous mixture

18.  b. Solventsdissolve other substances c. Solutesdissolve in a solvent

19. 2. “Like dissolves like” a. Polar solvents dissolvepolar solutes

20. b. Nonpolar solvents dissolvenonpolar solutes

21. c. Polar substances and nonpolar substances generally remain separate

23. C. Some compounds form acidsand bases 1. An acidreleases a hydrogen ion when it dissolves in water a. High H+ concentration   b. pHless than 7

24. 2. A baseremoves hydrogen ions from a solution a. low H+ concentration   b. pH greater than 7

25. 3. A neutral solution has a pH of 7

27. III. Carbon-Based Molecules (2.3) A. Carbon atoms have unique bonding properties 1. Carbon forms covalent bonds with up to four other atoms, including other carbon atoms.

28. 2. Carbon-based molecules have three general types of structures a. Straight chain b. Branched chain c. Ring

29. B. Many carbon based molecules are made of many small subunits bonded together 1. Monomersare the individual subunits  2. Polymersare made of many monomers

30. B. Four main types of carbon-based molecules are found in living things. 1. Carbohydratesare made of carbon, hydrogen, and oxygen a. Carbohydrates include sugars and starches b. Monosaccharidesare simple sugars. Includes glucose, fructose, and galactose (monomers)

31. c. Polysaccharide- Three types: • Cellulose- makes up plant cell walls • Starchor Amylose - plants store glucose in this form • Glycogen-glucose is stored in a branched form and stored in the liver and muscle cells for quick energy.

32. d. Carbohydrates can be broken down to provide energy for cells e. Some carbohydrates are part of cell structure

33. 2. Lipidsare nonpolar molecules that include fats, oils, waxes and steroids a. Many contain carbon chains called fatty acids b. Subunits: Fatty Acids (long chains of carbon bonded to hydrogen) and Glycerol.

34. c. Lipids have several different functions 1). Broken down as a source of energy

35. 2). Make up cell membranes

36. 3). Used to make hormones

37. e. Fats and oils have different types of fatty acids 1). Saturatedfatty acids (in animal fats) 2). Unsaturatedfatty acids (found in plants- in vegetable oil)

38. f. Phospholipidsmake up all cell membranes 1). Polar phosphate “head” 2). Nonpolar fatty acid “tails”

39. The length and the degree of unsaturation of fatty acid chains have a profound effect on membrane fluidity Unsaturated fatty acids create a kink, preventing the fatty acids from packing together as tightly  

40. 3. Proteinsare polymers of amino acid monomers a. 20 different amino acids. The body produces 12 and the rest come from diet

41. b. Proteins differ in the number and order of amino acids   1). Amino acids interact to give a protein its shape   2). Incorrect amino acids change a proteins structure and function

42. 4. Nucleic acids are polymers of monomers called nucleotides a. Nucleotidesare made of sugar, phosphate group, and a nitrogen base.

43. b. DNA storesgenetic information c. RNA buildsproteins

44. IV. Chemical Reactions (2.4) A. Bondsbreak and form during chemical reactions. 1. Reactantsare changed during a chemical reaction 2. Productsare made by a chemical reactions. C6H12O6 + 6O2 6CO2 + 6H2O reactants products

45. B. Bond energy is the amount of energy that breaks a bond 1. Energy is added To break bonds 2. Energy is released when bonds form

46. C. A reaction is at equilibriumwhen reactants and products form at the same rate. CO2 + H2O H2CO3

47. D. Chemical reactions release or absorb energy 1. Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.

48.  2. Exothermicreactions release more energy than they absorb. a. Reactants have higher bond energy than products b. Excess energy is released by the reaction

49. 3. Endothermicreactions absorb more energy than they release. a. Reactants have lower bond energy than products   a. Energy is absorbed by the reaction to make up the difference.

50. V. Enzymes(2.5) A. A catalysts lowersactivation energy 1. Catalystsare substances that speed upchemical reactions a. Decreaseactivation energy b. Increasereaction rate