1. Chapter 5
Macromolecules

2. The Molecules of Life
Another level in the hierarchy of biological organization is reached when small organic molecules are joined together

3. Macromolecules Large molecules composed of smaller molecules
Complex structure
Figure 5.1

4. Most macromolecules are polymers, built from monomers
3 classes are polymers
Carbohydrates
Proteins
Nucleic acids

5. Polymer
Lg. molecule consisting of many similar building blocks (monomers)

6. The Synthesis and Breakdown of Polymers
Condensation reactions (dehydration reactions)
(a) Dehydration reaction in the synthesis of a polymer HO H 1 2 3 4
H2O
Short polymer
Unlinked monomer
Longer polymer
Dehydration removes a water molecule, forming a new bond
Figure 5.2A

7. (b) Hydrolysis of a polymerHO 1 2 3 H 4
H2O
Hydrolysis adds a water molecule, breaking a bond
Figure 5.2B

8. Carbohydrates: fuel and building material
Sugars and their polymers

9. Sugars Monosaccharides Simplest sugars Fuel
Converted into other organic molecules
Combined into polymers

10. Examples of monosaccharides
Triose sugars (C3H6O3)
Pentose sugars (C5H10O5)
Hexose sugars (C6H12O6)
H C OH
H C OH
HO C H
H C OH
C O
HO C H H C O
Aldoses
Glyceraldehyde
Ribose
Glucose
Galactose
Dihydroxyacetone
Ribulose
Ketoses
Fructose
Figure 5.3

11. Monosaccharides Linear, or Rings 4C 3 2 OH Figure 5.4
H C OH
HO C H
H C O C 1 2 3 4 5 6 OH 4C
6CH2OH 5C
H OH
2 C 1C
3 C 2C
1 C
CH2OH HO
(a) Linear and ring forms. Chemical equilibrium between the linear and ring
structures greatly favors the formation of rings. To form the glucose ring,
carbon 1 bonds to the oxygen attached to carbon 5.
Figure 5.4

12. Disaccharides
2 monosaccharides
Joined by a glycosidic linkage

13. Examples of disaccharides
Dehydration reaction in the synthesis of maltose. The bonding of two glucose units forms maltose. The glycosidic link joins the number 1 carbon of one glucose to the number 4 carbon of the second glucose. Joining the glucose monomers in a different way would result in a different disaccharide.
Dehydration reaction in the synthesis of sucrose. Sucrose is a disaccharide formed from glucose and fructose. Notice that fructose, though a hexose like glucose, forms a five-sided ring.
(a)
(b) H HO
H OH OH O
CH2OH
H2O 1 2 4
1– 4 glycosidic linkage
1–2 glycosidic linkage
Glucose
Fructose
Maltose
Sucrose
Figure 5.5

14. Polysaccharides
Polymers of sugars

15. Storage Polysaccharides
Starch - glucose monomers
Major storage form of glucose in plants
Chloroplast
Starch
Amylose
Amylopectin
1 m
(a) Starch: a plant polysaccharide
Figure 5.6

16. (b) Glycogen: an animal polysaccharide
Glucose monomers
Storage form of glucose in animals
Mitochondria
Giycogen granules
0.5 m
(b) Glycogen: an animal polysaccharide
Glycogen
Figure 5.6

17. Structural Polysaccharides
Cellulose - Polymer of glucose
Different glycosidic linkages than starch
(c) Cellulose: 1– 4 linkage of  glucose monomers H O
CH2OH OH HO 4 C 1
(a)  and  glucose ring structures
(b) Starch: 1– 4 linkage of  glucose monomers
 glucose
 glucose
Figure 5.7 A–C

18. Major component of the plant cell walls
Plant cells
0.5 m
Cell walls
Cellulose microfibrils
in a plant cell wall 
Microfibril
CH2OH OH O
Glucose monomer
Parallel cellulose molecules are
held together by hydrogen
bonds between hydroxyl
groups attached to carbon
atoms 3 and 6.
About 80 cellulose
molecules associate
to form a microfibril, the
main architectural unit
of the plant cell wall.
A cellulose molecule
is an unbranched 
glucose polymer.
Cellulose
molecules
Figure 5.8

19. Cellulose, difficult to digest
Microbes in cow stomach
Figure 5.9

20. Chitin Exoskeleton of arthropods Surgical thread
(a) The structure of the
chitin monomer. O
CH2OH OH H NH C
CH3
(b) Chitin forms the exoskeleton
of arthropods. This cicada
is molting, shedding its old
exoskeleton and emerging
in adult form.
(c) Chitin is used to make a
strong and flexible surgical
thread that decomposes after
the wound or incision heals.
Figure 5.10 A–C

21. Lipids
Hydrophobic
Not polymers

22. (a) Dehydration reaction in the synthesis of a fat
Fats
Single glycerol and three fatty acids H O H H H H H H H H H H H H H H H H
O H C OH
Glycerol
Fatty acid
(palmitic acid) HO O
(a) Dehydration reaction in the synthesis of a fat
Ester linkage
Figure 5.11
(b) Fat molecule (triacylglycerol)

23. (a) Saturated fat and fatty acid
Saturated fatty acids
Max # of hydrogen atoms possible
No double bonds
(a) Saturated fat and fatty acid
Stearic acid
Figure 5.12

24. (b) Unsaturated fat and fatty acid
Unsaturated fatty acids
1 or more double bonds
(b) Unsaturated fat and fatty acid
cis double bond
causes bending
Oleic acid
Figure 5.12

25. (a) Structural formula (b) Space-filling model
Phospholipids
2 fatty acids, plus phosphate group
Hydrophilic “head” and hydrophobic “tails”
CH2 O P CH C
Phosphate
Glycerol
(a) Structural formula
(b) Space-filling model
Fatty acids
(c) Phospholipid
symbol
Hydrophobic tails
Hydrophilic
head
Hydrophobic
tails –
Hydrophilic head
Choline +
Figure 5.13
N(CH3)3

26. The structure of phospholipids
Bilayer arrangement found in cell membranes
Hydrophilic
head
WATER
Hydrophobic
tail
Figure 5.14

27. One steroid, cholesterol
Found in cell membranes
Precursor for some hormones HO
CH3
H3C
Figure 5.15

28. Proteins
Table 5.1

29. Protein catalyst, speeds up chemical reactions
Enzymes
Protein catalyst, speeds up chemical reactions
Substrate
(sucrose)
Enzyme
(sucrase)
Glucose OH
H O
H2O
Fructose
3 Substrate is converted
to products.
1 Active site is available for
a molecule of substrate, the
reactant on which the enzyme acts.
Substrate binds to
enzyme. 2
4 Products are released.
Figure 5.16

30. Polypeptides Polymers of amino acids A protein 1 or more polypeptides
Amino acids - carboxyl & amino groups
Properties due to side chains, (R groups)

31. 20 different amino acids make up proteinsH
H3N+ C
CH3 CH
CH2 NH
H2C
H2N
Nonpolar
Glycine (Gly)
Alanine (Ala)
Valine (Val)
Leucine (Leu)
Isoleucine (Ile)
Methionine (Met)
Phenylalanine (Phe)
Tryptophan (Trp)
Proline (Pro)
H3C
Figure 5.17 S

32. Polar Electrically chargedOH
CH2 C H
H3N+ O
CH3 CH SH
NH2
Polar
Electrically
charged –O
NH3+
NH2+
NH+ NH
Serine (Ser)
Threonine (Thr)
Cysteine
(Cys)
Tyrosine
(Tyr)
Asparagine
(Asn)
Glutamine
(Gln)
Acidic
Basic
Aspartic acid
(Asp)
Glutamic acid
(Glu)
Lysine (Lys)
Arginine (Arg)
Histidine (His)

33. Amino Acid (AA) Polymers
Linked by peptide bonds
DESMOSOMES OH
CH2 C N H O
Peptide bond SH
Side chains
H2O
Amino end (N-terminus)
Backbone
(a)
Figure 5.18
(b)
Carboxyl end (C-terminus) OH

34. Protein Conformation and Function
(a) ribbon model
(b) space-filling model
Groove
Figure 5.19

35. Four Levels of Protein Structure
Primary structure
Unique sequence of AAs
Figure 5.20 –
Amino acid subunits
+H3N Amino end o
Carboxyl end c
Gly
Pro
Thr
Glu
Seu
Lys
Cys
Leu
Met
Val
Asp
Ala
Arg
Ser
lle
Phe
His
Asn
Tyr
Trp
Lle

36. Secondary structure Folding or coiling of the polypeptide
 helix and the  pleated sheet O C
 helix
 pleated sheet
Amino acid subunits N H R H
Figure 5.20

37. 3-D shape of a polypeptide
Tertiary structure
3-D shape of a polypeptide
Results from interactions between AAs and R groups
CH2 CH
O H O C HO
NH3+ -O S
CH3
H3C
Hydrophobic interactions and van der Waals interactions
Polypeptide backbone
Hyrdogen bond
Ionic bond
Disulfide bridge

38. Quaternary structure 2 or more polypeptide subunits Polypeptide chain
Collagen
 Chains
 Chains
Hemoglobin
Iron
Heme

39. 4 levels of protein structure
+H3N
Amino end
Amino acid
subunits
helix

40. Sickle-cell hemoglobin
Hemoglobin structure and sickle-cell disease
Primary structure
Secondary and tertiary structures
Quaternary structure
Function
Red blood cell shape
Hemoglobin A
Molecules do not associate with one another, each carries oxygen.
Normal cells are full of individual hemoglobin molecules, each carrying oxygen  
10 m
Hemoglobin S
Molecules interact with one another to crystallize into a fiber, capacity to carry oxygen is greatly reduced.
 subunit 1 2 3 4 5 6 7
Normal hemoglobin
Sickle-cell hemoglobin
. . .
Figure 5.21
Exposed hydrophobic region
Val
Thr
His
Leu
Pro
Glul
Glu
Fibers of abnormal hemoglobin deform cell into sickle shape.

41. Denaturation Protein unravels and loses its native conformation
Renaturation
Denatured protein
Normal protein
Figure 5.22

42. Chaperonins Proteins that assist in folding of other proteins
Hollow cylinder
Cap
Chaperonin (fully assembled)
Steps of Chaperonin Action: An unfolded poly- peptide enters the cylinder from one end.
The cap attaches, causing the cylinder to change shape in such a way that it creates a hydrophilic environment for the folding of the polypeptide.
The cap comes off, and the properly folded protein is released.
Correctly folded protein
Polypeptide 2 1 3
Figure 5.23

43. X-ray crystallography
Determines molecule’s 3-D structure
X-ray diffraction pattern
Photographic film
Diffracted X-rays
X-ray source
X-ray beam
Crystal
Nucleic acid
Protein
(a) X-ray diffraction pattern
(b) 3D computer model
Figure 5.24

44. Nucleic acids store and transmit hereditary information Genes
Units of inheritance
Program AA sequence
Made of nucleic acids

45. The Roles of Nucleic Acids
There are two types of nucleic acids
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)

46. DNA
Stores information for the synthesis of proteins

47. Synthesis of mRNA in the nucleus
Directs RNA synthesis
Directs protein synthesis through RNA 1 2 3
Synthesis of mRNA in the nucleus
Movement of
mRNA into cytoplasm
via nuclear pore
Synthesis
of protein
NUCLEUS
CYTOPLASM
DNA
mRNA
Ribosome
Amino acids
Polypeptide
Figure 5.25

48. The Structure of Nucleic Acids
Polymers called polynucleotides
3’C
5’ end
5’C
3’ end OH
Figure 5.26 O
(a) Polynucleotide,
or nucleic acid

49. Consists of monomers called nucleotides
Nitrogenous
base
Nucleoside O O O P
CH2
5’C
3’C
Phosphate
group
Pentose
sugar
(b) Nucleotide
Figure 5.26

50. (c) Nucleoside components
Nucleotide Monomers
Made up of nucleosides and phosphate groups CH
Uracil (in RNA) U
Ribose (in RNA)
Nitrogenous bases Pyrimidines C N O H
NH2 HN
CH3
Cytosine
Thymine (in DNA) T HC NH
Adenine A
Guanine G
HOCH2 OH
Pentose sugars
Deoxyribose (in DNA) 4’ 5” 3’ 2’ 1’
Figure 5.26
(c) Nucleoside components

51. The sequence of bases(A, T, C, G) along a nucleotide polymer
Unique for each gene

52. DNA double helix 2 antiparallel nucleotide strands Figure 5.27 3’ end
Sugar-phosphate backbone
Base pair (joined by hydrogen bonding)
Old strands
Nucleotide about to be added to a new strand A
5’ end
New strands
Figure 5.27

53. Nitrogenous bases in DNA
Form hydrogen bonds in a complementary fashion (A with T only, and C with G only)

54. DNA and Proteins as Tape Measures of Evolution
Molecular comparisons among species