1. Structure & Function of Large Biological Molecules (Macromolecules)

2. *When given a molecular formula – be able to give the structural formula
Ball-and-Stick
Model
Space-Filling
Model
Name
(a) Methane
(b) Ethane
(c) Ethene
(ethylene)

3. Remember, number of covalent bonds is determined by the valence electrons (number of electrons in outermost energy level)
Number of covalent bonds formed (Commit these to Memory) H – 1 O – 2 N – 3 C - 4

4. Concept 5.1: Macromolecules are polymers, built from monomers
A polymer is a long molecule consisting of many similar building blocks
These small building-block molecules are called monomers
Three of the four classes of life’s organic molecules are polymers:
Carbohydrates
Proteins
Nucleic acids
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5. Carbohydrates include sugars and the polymers of sugars
Concept 5.2: Carbohydrates serve as fuel (energy) and building material
Carbohydrates include sugars and the polymers of sugars
The simplest carbohydrates are monosaccharides, or single sugars
Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks
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6. Sugars
Monosaccharides have molecular formulas that are usually multiples of CH2O ratio: 1:2:1
Glucose (C6H12O6) is the most common monosaccharide
Other examples are fructose, galactose
Glucose, fructose, and galactose have the same molecular formula, C6H12O6, but the atoms are arranged differently. This is the definition of an isomer.
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7. The #’s 1-6 represent the positions
Fig. 5-4b
The #’s 1-6 represent the positions
of 6 carbons in glucose
Figure 5.4 Linear and ring forms of glucose
(b) Abbreviated ring structure
Always start with oxygen in the ring and count carbons going clockwise

8. Disaccharide means “2 sugars”. Know the following disaccharides:
A disaccharide is formed when the dehydration synthesis reaction joins two monosaccharides.
Disaccharide means “2 sugars”.
Know the following disaccharides:
Glucose + glucose = maltose (think Whoppers)
Glucose + fructose = sucrose (table sugar)
Glucose + galactose = lactose (milk sugar)
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9. (a) Dehydration reaction in the synthesis of the disachharide, maltose
1–4
glycosidic
linkage
Glucose
Glucose
Maltose
(a) Dehydration reaction in the synthesis of the disachharide, maltose
1–2
glycosidic
linkage
Figure 5.5 Examples of disaccharide synthesis
Glucose
Fructose
Sucrose
(b) Dehydration reaction in the synthesis of the disaccharide, sucrose

10. Hydrolysis – “adding water breaks bonds”
Hydrolysis – “adding water breaks bonds”. It is the opposite of dehydration synthesis – start with polymer or bigger molecule, add water and end up with monomers or building blocks.
+ H20 →
Now 2 separate molecules
maltose
glucose
glucose

11. Storage Polysaccharides
Starch, a storage polysaccharide of plants, consists entirely of glucose monomers
Plants store surplus starch as granules within chloroplasts and other plastids
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12. (a) Starch: a plant polysaccharide
Fig. 5-6
Chloroplast
Starch
Mitochondria
Glycogen granules
0.5 µm
1 µm
Figure 5.6 Storage polysaccharides of plants and animals
Glycogen
(a) Starch: a plant polysaccharide
(b) Glycogen: an animal polysaccharide

13. Glycogen is a storage polysaccharide in animals
Humans and other vertebrates store glycogen mainly in liver and muscle cells.
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14. Structural Polysaccharides
The polysaccharide cellulose is a major component of the tough wall of plant cells
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15. (b) Starch: 1–4 linkage of glucose monomers
Fig. 5-7bc
(b) Starch: 1–4 linkage of glucose monomers
Figure 5.7 Starch and cellulose structures
(c Cellulose: 1–4 linkage of glucose monomers

16. cellulose Cell walls Cellulose microfibrils in a plant cell wall
Fig. 5-8
Cell walls
Cellulose
microfibrils
in a plant
cell wall
cellulose
Microfibril
10 µm
0.5 µm
Cellulose
molecules
Figure 5.8 The arrangement of cellulose in plant cell walls
Glucose
monomer

17. Enzymes that digest starch can’t break bonds in cellulose
Cellulose in human food passes through the digestive tract as insoluble fiber
Some microbes use enzymes to digest cellulose
Many herbivores, from cows to termites, have symbiotic relationships with these microbes
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18. Fig. 5-9
Figure 5.9 Cellulose-digesting prokaryotes are found in grazing animals such as this cow

19. Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods
Chitin also provides structural support for the cell walls of many fungi
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20. Chitin – a structural carbohydrate
Fig. 5-10
Chitin – a structural carbohydrate
containing nitrogen
(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.
Figure 5.10 Chitin, a structural polysaccharide

21. Concept 5.3: Lipids are a diverse group of hydrophobic molecules
Lipids are the one class of large biological molecules that do not form polymers
Lipids are hydrophobic & form nonpolar covalent bonds
The most biologically important lipids are fats, phospholipids, and steroids, waxes & oils
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22. Fats
Fats are constructed from two types of smaller molecules: glycerol and 3 fatty acids
Glycerol is a three-carbon alcohol with a hydroxyl group (-OH) attached to each carbon
A fatty acid consists of a carboxyl group (-COOH) attached to a long carbon skeleton
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23. Dehydration reaction in the synthesis of a fat
Fig. 5-11a
Fatty acid
Glycerol
Figure 5.11 The synthesis and structure of a fat, or triacylglycerol
(a)
Dehydration reaction in the synthesis of a fat

24. 3 water molecules are removed to attach a fatty acid chain to each of the 3 carbons in glycerol
Figure 5.11 The synthesis and structure of a fat, or triacylglycerol
(b)
Fat molecule

25. Unsaturated fatty acids have one or more double bonds
Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds
Unsaturated fatty acids have one or more double bonds
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26. Structural formula of a saturated fat molecule Stearic acid, a
Fig. 5-12a
Structural
formula of a
saturated fat
molecule
Figure 5.12 Examples of saturated and unsaturated fats and fatty acids
Stearic acid, a
saturated fatty
acid
(a)
Saturated fat

27. unsaturated fatty acid Structural formula of an unsaturated
Fig. 5-12b
Structural formula
of an unsaturated
fat molecule
Oleic acid, an
unsaturated
fatty acid
Figure 5.12 Examples of saturated and unsaturated fats and fatty acids
cis double
bond causes
bending
(b)
Unsaturated fat

28. Most animal fats are saturated
Fats made from saturated fatty acids are called saturated fats, and are solid at room temperature
Most animal fats are saturated
Fats made from unsaturated fatty acids are called unsaturated fats or oils, and are liquid at room temperature
Plant fats and fish fats are usually unsaturated
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29. A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits
Hydrogenation is the process of converting unsaturated fats to saturated fats by adding hydrogen
Trans fats may contribute more than saturated fats to cardiovascular disease
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30. The major function of fats is energy storage
Humans and other mammals store their fat in adipose cells
Adipose tissue also cushions vital organs and insulates the body
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31. Phospholipids
In a phospholipid, two fatty acids and a phosphate group are attached to glycerol
The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head
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32. Choline Hydrophilic head Phosphate Glycerol Fatty acids
Fig. 5-13
Choline
Hydrophilic head
Phosphate
Glycerol
Fatty acids
Hydrophobic tails
Hydrophilic
head
Figure 5.13 The structure of a phospholipid
Hydrophobic
tails
(a)
Structural formula
(b)
Space-filling model
(c)
Phospholipid symbol

33. Phospholipids are the major component of all cell membranes
When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the interior
Phospholipids are the major component of all cell membranes
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34. Cell membrane- Phopholipid bilayer
Fig. 5-14
Hydrophilic
head
WATER
Figure 5.14 Bilayer structure formed by self-assembly of phospholipids in an aqueous environment
WATER
Cell membrane-
Phopholipid bilayer
Hydrophobic
tail

35. Steroids
Steroids are lipids characterized by a carbon skeleton consisting of four fused rings
Cholesterol, an important steroid, is a component in animal cell membranes
Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease
For the Cell Biology Video Space Filling Model of Cholesterol, go to Animation and Video Files.
For the Cell Biology Video Stick Model of Cholesterol, go to Animation and Video Files.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

36. Steroids (4 FUSED CARBON RINGS)
Fig. 5-15
Steroids (4 FUSED CARBON RINGS)
Figure 5.15 Cholesterol, a steroid
EX) Cholesterol