1. PowerLecture: Chapter 3
Molecules of Life

2. Hydrogen and other elements covalently bonded to carbon
Organic Compounds
Hydrogen and other elements covalently bonded to carbon
Carbohydrates
Lipids
Proteins
Nucleic Acids

3. Organic Compounds carbon (C) calcium (C) sodium (Na) oxygen (O)
phosphorous (P)
chlorine (Cl)
hydrogen (H)
potassium (K)
magnesium (Mg)
nitrogen (N)
iron (S)
iron (Fe)
p.34a

4. Organic Compounds structural formula for methane ball-and-stick model
space-filling model
p.34b

5. Carbon’s Bonding Behavior
Outer shell of carbon has 4 electrons; can hold 8
Each carbon atom can form covalent bonds with up to four atoms

6. Bonding Arrangements Carbon atoms can form chains or rings
Other atoms project from the carbon backbone

7. Simplified structural formula for a six-carbon ring
Organic Compounds or
Simplified structural formula for a six-carbon ring
icon for a six-carbon ring
p.34e

8. Organic Compounds
Fig. 3-2, p.35

9. Molecular models of the protein hemoglobin

10. Organic Compound
Fig. 3-3, p.35

11. Functional Groups
Atoms or clusters of atoms that are covalently bonded to carbon backbone
Give organic compounds their different properties

12. Examples of Functional Groups
Hydroxyl group - OH
Amino group - NH3+
Carboxyl group - COOH
Phosphate group - PO3-
Sulfhydryl group - SH

13. Types of Reactions Functional group transfer Electron transfer
Rearrangement
Condensation
Cleavage

14. Common Functional Groups in Biological Molecules
Fig. 3-4, p.36

15. Functional group

16. Functional Groups in Hormones
Estrogen and testosterone are hormones responsible for observable differences in traits between male and female wood ducks
Differences in position of functional groups attached to ring structure (pg 36)
An Estrogen
Testosterone

17. Fig. 3-5b, p.36

18. Condensation Reactions
Form polymers from subunits
Enzymes remove -OH from one molecule, H from another, form bond between two molecules
Discarded atoms can join to form water

19. Condensation
Fig. 3-6a, p.38

20. Hydrolysis A type of cleavage reaction
Breaks polymers into smaller units
Enzymes split molecules into two or more parts
An -OH group and an H atom derived from water are attached at exposed sites

21. Hydrolysis
Fig. 3-6b, p.38

22. Condensation and hydrolysis

23. Consider Methane
Methane, a “lifeless” hydrocarbon, is present in vast methane hydrate deposits beneath the ocean floor
Methane hydrate disintegration can be explosive, causing a chain reaction that depletes oxygen
Evidence points to such an event ending the Permian period 250 million years ago

24. Methane Ball-and-stick model. Specific colors are used to distinguish
one kind of atom from another.
Space-filling model, used to depict volumes of space occupied by electrons.
Structural formula, showing four single covalent bonds.

25. Carbohydrates Monosaccharides (simple sugars) Oligosaccharides
(short-chain carbohydrates)
Polysaccharides
(complex carbohydrates)

26. Monosaccharides Simplest carbohydrates
Most are sweet tasting, water soluble
Most have 5- or 6-carbon backbone
Glucose (6 C) Fructose (6 C)
Ribose (5 C) Deoxyribose (5 C)

27. Two Monosaccharides
glucose
fructose
Fig. 3-7, p.38

28. Disaccharides Type of oligosaccharide
glucose
fructose
Type of oligosaccharide
Two monosaccharides covalently bonded
Formed by condensation reaction
+ H2O
sucrose
Fig. 3-7b, p.38

29. Polysaccharides Straight or branched chains of many sugar monomers
Most common are composed entirely of glucose
Cellulose
Starch (such as amylose)
Glycogen

30. Cellulose & Starch Differ in bonding patterns between monomers
Cellulose - tough, indigestible, structural material in plants
Starch - easily digested, storage form in plants

31. Cellulose and Starch
Fig. 3-8, p.38

32. Glycogen Sugar storage form in animals
Large stores in muscle and liver cells
When blood sugar decreases, liver cells degrade glycogen, release glucose
Fig. 3-9, p.38

33. Fig. 3-9, p.39

34. Structure of starch and cellulose

35. Chitin Polysaccharide
Nitrogen-containing groups attached to glucose monomers
Structural material for hard parts of invertebrates, cell walls of many fungi

36. Chitin
Chitin occurs in protective body coverings of many animals, including ticks (pg 39)
Fig. 3-10a, p.39

37. Fig. 3-10b, p.39

38. Lipids Most include fatty acids
Fats
Phospholipids
Waxes
Sterols and their derivatives have no fatty acids
Tend to be insoluble in water

39. Fats Fatty acid(s) attached to glycerol Triglycerides are most common
Fig. 3-12, p.40

40. Fatty Acids Carboxyl group (-COOH) at one end
Carbon backbone (up to 36 C atoms)
Saturated - Single bonds between carbons
Unsaturated - One or more double bonds

41. Three Fatty Acids
Fig. 3-11, p.40

42. Fatty acids

43. Triglyceride formation

44. Fig. 3-12a, p.40

45. Phospholipids
Main components of cell membranes

46. Phospholipid structure

47. Waxes
Long-chain fatty acids linked to long chain alcohols or carbon rings
Firm consistency, repel water
Important in water-proofing

48. Waxes Bees construct honeycombs from their own waxy secretions
Fig. 3-14, p.41

49. Sterols and Derivatives
No fatty acids
Rigid backbone of four fused-together carbon rings
Cholesterol - most common type in animals
Fig. 3-14, p.41

50. Cholesterol

51. Amino Acid Structure
carboxyl
group
amino
group
R group

52. Structure of an amino acid

53. Properties of Amino Acids
Determined by the “R group”
Amino acids may be:
Non-polar
Uncharged, polar
Positively charged, polar
Negatively charged, polar

54. Protein Synthesis
Protein is a chain of amino acids linked by peptide bonds
Peptide bond
Type of covalent bond
Links amino group of one amino acid with carboxyl group of next
Forms through condensation reaction

56. Fig. 3-15b, p.42

57. Fig. 3-15c, p.42

58. Fig. 3-15d, p.42

59. Fig. 3-15e, p.42

60. Peptide bond formation

61. -N-C-C-N-C-C-N-C-C-N-
Primary Structure
Sequence of amino acids
Unique for each protein
Two linked amino acids = dipeptide
Three or more = polypeptide
Backbone of polypeptide has N atoms:
-N-C-C-N-C-C-N-C-C-N-
one peptide group

62. Protein Shapes Fibrous proteins Globular proteins
Polypeptide chains arranged as strands or sheets
Globular proteins
Polypeptide chains folded into compact, rounded shapes

63. Primary Structure & Protein Shape
Primary structure influences shape in two main ways:
Allows hydrogen bonds to form between different amino acids along length of chain
Puts R groups in positions that allow them to interact

64. Secondary Structure
Hydrogen bonds form between different parts of polypeptide chain
These bonds give rise to coiled or extended pattern
Helix or pleated sheet

65. Examples of Secondary Structure

66. Secondary and tertiary structure

67. Tertiary Structure
heme group
Folding as a result of interactions between R groups
coiled and twisted polypeptide chain of one globin molecule

68. Quaternary Structure
Some proteins are made up of more than one polypeptide chain
Hemoglobin

69. alpha globin
alpha globin
heme
beta globin
beta globin
Fig. 3-17, p.44

70. Globin and hemoglobin structure

71. Polypeptides with Attached Organic Compounds
Lipoproteins
Proteins combined with cholesterol, triglycerides, phospholipids
Glycoproteins
Proteins combined with oligosaccharides

72. Globin and hemoglobin structure

73. Denaturation Disruption of three-dimensional shape
Breakage of weak bonds
Causes of denaturation: pH
Temperature
Destroying protein shape disrupts function

74. Fig. 3-18c, p.45

75. Structure of an amino acid

76. a Normal amino acid sequence at the start of a beta change for hemoglobin
GLUTAMATE
VALINE
HISTIDINE
LEUCINE
THREONINE
PROLINE
GLUTAMATE
Fig. 3-18a, p.45

77. b One amino acid substitution results in the abnormal beta chain in HbS molecules. During protein synthesis, valine was added instead of glutamate at the sixth position of the growing polypeptide chain.
VALINE
HISTIDINE
LEUCINE
THREONINE
PROLINE
VALINE
GLUTAMATE
Fig. 3-18b, p.45

78. c Glutamate has an overall negative charge; valine has no net charge
c Glutamate has an overall negative charge; valine has no net charge. The difference gives rise to a water-repellant, sticky patch on HbS molcules. They stick together because of that patch, forming rod-shaped clumps that distort normally rounded red blood cells into sickle shapes. (A sickle is a farm tool that has a crescent-shaped blade.)
sickle cell
normal cell
Fig. 3-18c, p.45

79. Clumping of cells in bloodstream
Circulatory problems, damage to brain, lungs, heart, skeletal muscles, gut, and kidneys
Heart failure, paralysis, pneumonia, rheumatism, gut pain, kidney failure
Spleen concentrates sickle cells
Spleen enlargement
Immune system compromised
Rapid destruction of sickle cells
Anemia, causing weakness,fatigue, impaired development,heart chamber dilation
Impaired brain function, heart failure
Fig. 3-18d, p.45

80. Nucleotide Structure Sugar At least one phosphate group Base
Ribose or deoxyribose
At least one phosphate group
Base
Nitrogen-containing
Single or double ring structure

81. Nucleotide Functions Energy carriers Coenzymes Chemical messengers
Building blocks for nucleic acids

82. three phosphate groups
ATP - A Nucleotide
base
three phosphate groups
sugar

83. Nucleic Acids Composed of nucleotides Single- or double-stranded
Adenine
Cytosine
Composed of nucleotides
Single- or double-stranded
Sugar-phosphate backbone

84. Structure of ATP

85. Bonding Between Bases in Nucleic Acids
THYMINE
(T)
base with a
single-ring
structure
CYTOSINE
(C)
base with a
single-ring
structure
Fig. 3-20, p.46

86. Nucleotide subunits of DNA

87. DNA Double-stranded Consists of four types of nucleotides A bound to T
C bound to G

88. RNA Usually single strands Four types of nucleotides
Unlike DNA, contains the base uracil in place of thymine
Three types are key players in protein synthesis

90. Fig. 3-22, p.49

91. Fig. 3-23, p.49

92. Fig. 3-23, p.49