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Macromolecules
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Organic Compounds
Compounds that contain CARBON are called organic.
Macromolecules are large organic molecules.
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Carbon (C)
Carbon has 4 electrons in outer shell.
Carbon can form covalent bonds with as many as 4 other atoms (elements).
Usually with C, H, O or N.
Example: CH4(methane)
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Macromolecules
Large organic molecules.
Also called POLYMERS.
Made up of smaller “building blocks” called MONOMERS.
Examples:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids (DNA and RNA)
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5. A polymer
Is a long molecule consisting of many similar building blocks called monomers
Specific monomers make up each macromolecule
E.g. amino acids are the monomers for proteins

6. Question: How Are Macromolecules Formed?
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7. Answer: Dehydration Synthesis
Also called “condensation reaction”
Forms polymers by combining monomers by “removing water”. HO H
H2O HO H
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8. The Synthesis and Breakdown of Polymers
Monomers form larger molecules by condensation reactions called dehydration synthesis
(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

9. Question: How are Macromolecules separated or digested?
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Answer: Hydrolysis
Separates monomers by “adding water” HO H
H2O HO H
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11. The Synthesis and Breakdown of Polymers
Polymers can disassemble by
Hydrolysis (addition of water molecules)
(b) Hydrolysis of a polymer HO 1 2 3 H 4
H2O
Hydrolysis adds a water molecule, breaking a bond
Figure 5.2B

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Carbohydrates
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Carbohydrates
Small sugar molecules to large sugar molecules.
Examples:
A. monosaccharide
B. disaccharide
C. polysaccharide
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Carbohydrates
Monosaccharide: one sugar unit
Examples: glucose (C6H12O6)
deoxyribose
ribose
Fructose
Galactose
glucose
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15. Sugars Monosaccharides Are the simplest sugars Can be used for fuel
Can be converted into other organic molecules
Can be combined into polymers

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Carbohydrates
Disaccharide: two sugar unit
Examples:
Sucrose (glucose+fructose)
Lactose (glucose+galactose)
Maltose (glucose+glucose)
glucose
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Carbohydrates
Polysaccharide: many sugar units
Examples: starch (bread, potatoes)
glycogen (beef muscle)
cellulose (lettuce, corn)
glucose
cellulose
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18. Storage Polysaccharides
Chloroplast
Starch
Amylose
Amylopectin
1 m
(a) Starch: a plant polysaccharide
Figure 5.6
Starch
Is a polymer consisting entirely of glucose monomers
Is the major storage form of glucose in plants

19.  Structural Polysaccharide Cellulose
Is a major component of the tough walls that enclose plant cells
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

20. Cellulose is difficult to digest
Cows have microbes in their stomachs to facilitate this process
Figure 5.9

21. Chitin, another important structural polysaccharide
Is found in the exoskeleton of arthropods
Can be used as 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

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Lipids
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Lipids
General term for compounds which are not soluble in water.
Lipids are soluble in hydrophobic solvents.
Remember: “stores the most energy”
Examples: 1. Fats
2. Phospholipids
3. Oils
4. Waxes
5. Steroid hormones
6. Triglycerides
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Lipids
Six functions of lipids:
1. Long term energy storage
2. Protection against heat loss (insulation)
3. Protection against physical shock
4. Protection against water loss
5. Chemical messengers (hormones)
6. Major component of membranes (phospholipids)
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Lipids
Triglycerides: composed of 1 glycerol and 3 fatty acids. H
H-C----O
glycerol O
C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3 = O
C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3 =
fatty acids O
C-CH2-CH2-CH2-CH
=CH-CH2-CH2-CH2-CH2-CH3 =
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Fatty Acids
There are two kinds of fatty acids you may see these on food labels:
1. Saturated fatty acids: no double bonds (bad)
2. Unsaturated fatty acids: double bonds (good) O
C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3 =
saturated O
C-CH2-CH2-CH2-CH
=CH-CH2-CH2-CH2-CH2-CH3 =
unsaturated
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27. (a) Structural formula (b) Space-filling model
Phospholipid structure
Consists of a 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

28. The structure of phospholipids
Results in a bilayer arrangement found in cell membranes
Hydrophilic
head
WATER
Hydrophobic
tail
Figure 5.14

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Proteins
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30. Proteins
Proteins have many structures, resulting in a wide range of functions
Proteins do most of the work in cells and act as enzymes
Proteins are made of monomers called amino acids

31. An overview of protein functions
Table 5.1

32. Proteins (Polypeptides)
Amino acids (20 different kinds of aa) bonded together by peptide bonds (polypeptides).
Six functions of proteins:
1. Storage: albumin (egg white)
2. Transport: hemoglobin
3. Regulatory: hormones
4. Movement: muscles
5. Structural: membranes, hair, nails
6. Enzymes: cellular reactions
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33. Enzymes
Are a type of protein that acts as a catalyst, speeding 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

34. Polypeptides Polypeptides Are polymers (chains) of amino acids
A protein
Consists of one or more polypeptides

35. Sickle-Cell Disease: A Simple Change in Primary Structure
Results from a single amino acid substitution in the protein hemoglobin

36. Sickle-cell hemoglobin
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.

37. What Determines Protein Conformation?
Protein conformation Depends on the physical and chemical conditions of the protein’s environment
Temperature, pH, etc. affect protein structure

38. Denaturation is when a protein unravels and loses its native conformation (shape)
Renaturation
Denatured protein
Normal protein
Figure 5.22

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Nucleic Acids
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40. Nucleic Acids Nucleic acids store and transmit hereditary information
Genes
Are the units of inheritance
Program the amino acid sequence of polypeptides
Are made of nucleotide sequences on DNA

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Nucleic acids
Two types:
a. Deoxyribonucleic acid (DNA- double helix)
b. Ribonucleic acid (RNA-single strand)
Nucleic acids are composed of long chains of nucleotides linked by dehydration synthesis.
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42. Deoxyribonucleic Acid
DNA
Stores information for the synthesis of specific proteins
Found in the nucleus of cells

43. Synthesis of mRNA in the nucleus
DNA Functions
Directs RNA synthesis (transcription)
Directs protein synthesis through RNA (translation) 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

44. Consists of two antiparallel nucleotide strands
The DNA double helix
Consists of two antiparallel nucleotide strands
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

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Nucleic acids
Nucleotides include:
phosphate group
pentose sugar (5-carbon)
nitrogenous bases:
adenine (A)
thymine (T) DNA only
uracil (U) RNA only
cytosine (C)
guanine (G)
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Nucleotide O
O=P-O
Phosphate
Group N
Nitrogenous base
(A, G, C, or T)
CH2 O C1 C4 C3 C2 5
Sugar
(deoxyribose)
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DNA - double helix P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A
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48. DNA and Proteins as Tape Measures of Evolution
Molecular comparisons
Help biologists sort out the evolutionary connections among species