1. UNIT 1: INTRODUCING BIOLOGY 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 atom is the smallest basic unit of matter
2. An element is one type of atom
3. An atom has a nucleus and electrons
   

4. a. The nucleus has protons and neutrons
b. Electrons are in energy levels outside the nucleus
   

5. 4. A compound is 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. Ions form when atoms gain or lose electrons
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. 1. A covalent bond forms when atoms share a pair of electrons
a. Multiple covalent bonds
b. Diatomic molecules
   

8. 2. A molecule is two or more atoms held together by covalent bonds
   

9. A. Life depends on hydrogen bonds in water
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
   

10. b. Nonpolar molecules do not have charged regions
   

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

12. 2. Hydrogen bonds are responsible for three important properties of water.
   
a. High specific heat
b. Cohesion- attraction between molecules of the same substance (because of hydrogen bonds, water is very cohesive)

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

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

15. b. Solvents dissolve other substances c. Solutes dissolve in a solvent
c. Solutes dissolve in a solvent
   

16. a. Polar solvents dissolve polar solutes
2. “Like dissolves like”
a. Polar solvents dissolve polar solutes
b. Nonpolar solvents dissolve nonpolar solutes
c. Polar substances and nonpolar substances generally remain separate   
   

18. C. Some compounds form acids and bases
1. An acid releases a hydrogen ion when it dissolves in water
a. High H+ concentration
  b. pH less than 7
   

19. 2. A base removes hydrogen ions from a solution. a
2. A base removes hydrogen ions from a solution a. low H+ concentration
  b. pH greater than 7
   

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

22. 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.
   

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

24. 1. Monomers are the individual subunits
B. Many carbon based molecules are made of many small subunits bonded together
   
1. Monomers are the individual subunits
 2. Polymers are made of many monomers

25. 1. Carbohydrates are made of carbon, hydrogen, and oxygen
B. Four main types of carbon-based molecules are found in living things.
1. Carbohydrates are made of carbon, hydrogen, and oxygen
   
a. Carbohydrates include sugars and starches
b.Monosaccharides are simple (single) sugars
c. Disaccharides are double sugars

26. c. Polysaccharides include starches, cellulose, and glycogen
   
   
d. Carbohydrates can be broken down to provide energy for cells
e. Some carbohydrates are part of cell structure

27. (a) Starch: a plant polysaccharide
Fig. 5-6
Chloroplast
Starch
Mitochondria
Glycogen granules
0.5 µm
1 µm
Amylose
Glycogen
Amylopectin
(a) Starch: a plant polysaccharide
(b) Glycogen: an animal polysaccharide

28. Cell walls Cellulose microfibrils in a plant cell wall Microfibril
Fig. 5-8
Cell walls
Cellulose
microfibrils
in a plant
cell wall
Microfibril
10 µm
0.5 µm
Cellulose
molecules
Glucose
monomer

29. (a) The structure of the chitin monomer. (b) (c) Chitin forms the
Fig. 5-10
(a)
The structure
of the chitin
monomer.
(b)
Chitin forms the
exoskeleton of
arthropods.
(c)
Chitin is used to make
a strong and flexible
surgical thread.

30. a. Many contain carbon chains called fatty acids
2. Lipids are nonpolar molecules that include fats, oils, and cholesterol
a. Many contain carbon chains called fatty acids
b. Fats and oils contain fatty acids bonded to glycerol.
   

31. Fatty acid (palmitic acid)
Fig. 5-11
Fatty acid
(palmitic acid)
Glycerol
(a) Dehydration reaction in the synthesis of a fat
Ester linkage
(b) Fat molecule (triacylglycerol)

32. Fat molecule (triacylglycerol)
Fig. 5-11b
Ester linkage
(b)
Fat molecule (triacylglycerol)

33. c. Lipids have several different functions
1). Broken down as a source of energy
2). Make up cell membranes
3). Used to make hormones
   

34. d. Fats and oils have different types of fatty acids
1). Saturated fatty acids
2). Unsaturated fatty acids
   

35. Structural formula of a saturated fat molecule Stearic acid, a
Fig. 5-12a
Structural
formula of a
saturated fat
molecule
Stearic acid, a
saturated fatty
acid
(a)
Saturated fat

36. unsaturated fatty acid Oleic acid, an cis double bond causes bending
Fig. 5-12b
Structural formula
of an unsaturated
fat molecule
Oleic acid, an
unsaturated
fatty acid
cis double
bond causes
bending
(b)
Unsaturated fat

37. Structural formula of a saturated fat molecule Stearic acid, a
Fig. 5-12
Structural
formula of a
saturated fat
molecule
Stearic acid, a
saturated fatty
acid
(a) Saturated fat
Structural formula
of an unsaturated
fat molecule
Oleic acid, an
unsaturated
fatty acid
cis double
bond causes
bending
(b) Unsaturated fat

38. e. Phospholipids make up all cell membranes 1). Polar phosphate “head”
   
1). Polar phosphate “head”
2). Nonpolar fatty acid “tails”

39. Choline Hydrophilic head Phosphate Glycerol Fatty acids
Fig. 5-13
Choline
Hydrophilic head
Phosphate
Glycerol
Fatty acids
Hydrophobic tails
Hydrophilic
head
Hydrophobic
tails
(a)
Structural formula
(b)
Space-filling model
(c)
Phospholipid symbol

40. Fig. 5-14
Hydrophilic
head
WATER
Hydrophobic
tail
WATER

41. 3. Proteins are polymers of amino acid monomers
   
a. Twenty different amino acids are used to build proteins in organisms

42. b. Amino acids differ in side groups, or R groups
c. Amino acids are linked by peptide bonds
   

43. +H3N Primary Structure Amino end Amino acid subunits 1 5 10 15 20 25
Fig. 5-21a
Primary Structure 1 5
+H3N
Amino end 10
Amino acid
subunits 15 20 25

44. Fig. 5-21b +H3N Amino end Amino acid subunits Carboxyl end 1 5 10 1520 25 75 80 85 90 95
105
100
110
115
120
125
Carboxyl end

45. A ribbon model of lysozyme
Fig. 5-19a
Groove
(a)
A ribbon model of lysozyme

46. Hydrophobic interactions and van der Waals interactions Polypeptide
Fig. 5-21f
Hydrophobic
interactions and
van der Waals
interactions
Polypeptide
backbone
Hydrogen
bond
Disulfide bridge
Ionic bond

47. d. 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
   

48. Protein Types Enzymes Contractile Defensive Hormonal Receptor Sensory
Storage
Structural
Transport

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

50. Nucleotide: Monomer of Nucleic Acids

51. b. DNA stores genetic information c. RNA builds proteins
c. RNA builds proteins
   

52. Fig. 5-UN2

53. Fig. 5-UN2a

54. Fig. 5-UN2b

55. C6H12O6 + O2 CO2 + H2O CO2 + H2O C6H12O6 + O2
IV. Chemical Reactions (2.4)
A. Bonds break and form during chemical reactions.
1. Reactants are changed during a chemical reaction
2. Products are made by a chemical reactions.
   
Cellular Respiration
Photosynthesis
C6H12O6 + O CO2 + H2O
CO2 + H2O C6H12O6 + O2
reactants
products

56. 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
   

57. C. A reaction is at equilibrium when reactants and products form at the same rate.
   
CO2 + H2O H2CO3

58. 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.
   

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

60. 3. Endothermic reactions 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.
   

61. A. A catalysts lowers activation energy
V. Enzymes (2.5)
A. A catalysts lowers activation energy
1. Catalysts are substances that speed up chemical reactions
a. Decrease activation energy
b. Increase reaction rate
   

62. 1. Enzymes are catalysts in living things
B. Enzymes allow chemical reactions to occur under tightly controlled conditions.
   
1. Enzymes are catalysts in living things
a. Enzymes are needed for almost all processes
b. Most enzymes are proteins

63. C. Disruptions in homeostasis can prevent enzymes from functioning.
1. Enzymes function best in a small range of conditions
2. Changes in temperature and pH can break hydrogen bonds.
3. An enzyme’s function depends on its structure
   

65. D. An enzyme’s structure allows only
D. An enzyme’s structure allows only certain reactants to bind to the enzyme
1. Substrates
2. Active Site
   

66. E. The lock-and-key model helps illustrate how enzymes function
1. Substrates brought together
2. bonds in substrates weakened