1. Carbon and the Molecular Diversity of Life3
Carbon and the Molecular Diversity of Life

2. Do now: Compare and contrast dehydration synthesis with hydrolysis
How are alpha and beta glucose molecules different? How does this affect the structure of their polymers?
Compare and contrast saturated vs unsaturated fats
HW: read the textbook section on proteins and annotate your notes.
Watch and supplement your notes on bozeman videos for carbohydrates and lipids

3. Overview: Carbon Compounds and Life
Aside from water, living organisms consist mostly of carbon-based compounds
Carbon is unparalleled in its ability to form large, complex, and diverse molecules
A compound containing carbon is said to be an organic compound
**contains carbon and hydrogen**
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4. Concept 3.1: Carbon atoms can form diverse molecules by bonding to four other atoms
An atom’s electron configuration determines the kinds and number of bonds the atom will form with other atoms
This is the source of carbon’s versatility
How many valence electrons does carbon have?
How many bonds is it able to make?
Is it more likely to make ionic or covalent bonds?
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5. Molecular Diversity Arising from Variation in Carbon Skeletons
Carbon chains form the skeletons of most organic molecules
Carbon chains vary in length and shape
(a) Length
(b) Branching
(c) Double bond position
(d) Presence of rings
Ethane
Propane
Butane
Benzene
Cyclohexane
1-Butene
2-Butene
2-Methylpropane
(isobutane)
Animation: Carbon Skeletons
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6. Many organic molecules, such as fats, have hydrocarbon components
Hydrocarbons are organic molecules consisting of only carbon and hydrogen
Many organic molecules, such as fats, have hydrocarbon components
Hydrocarbons can undergo reactions that release a large amount of energy
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7. The Chemical Groups Most Important to Life
Functional groups are the components of organic molecules that are most commonly involved in chemical reactions
The number and arrangement of functional groups give each molecule its unique properties
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8. The seven functional groups that are most important in the chemistry of life:
Hydroxyl group
Carbonyl group
Carboxyl group
Amino group
Sulfhydryl group
Phosphate group
Methyl group
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9. Ethanol, the alcohol present in alcoholic beverages
Figure 3.5aa
Hydroxyl group ( OH)
Alcohol
(The specific name
usually ends in -ol.)
(may be written HO )
Ethanol, the alcohol present
in alcoholic beverages
Figure 3.5aa Some biologically important chemical groups (part 2: hydroxyl) 9

10. group is within a carbon skeleton
Figure 3.5ab
Carbonyl group ( C O)
Ketone if the carbonyl
group is within a carbon
skeleton
Aldehyde if the carbonyl
group is at the end of a carbon skeleton
Figure 3.5ab Some biologically important chemical groups (part 3: carbonyl)
Acetone, the simplest ketone
Propanal, an aldehyde 10

11. Acetic acid, which gives vinegar its sour taste Ionized form of COOH
Figure 3.5ac
Carboxyl group ( COOH)
Carboxylic acid, or
organic acid
Figure 3.5ac Some biologically important chemical groups (part 4: carboxyl)
Acetic acid, which gives
vinegar its sour taste
Ionized form of COOH
(carboxylate ion),
found in cells 11

12. (note its carboxyl group) Ionized form of NH2 found in cells
Figure 3.5ad
Amino group ( NH2)
Amine
Figure 3.5ad Some biologically important chemical groups (part 5: amino)
Glycine, an amino acid
(note its carboxyl group)
Ionized form of NH2
found in cells 12

13. Sulfhydryl group ( SH) Thiol (may be written HS ) Cysteine, a sulfur-
Figure 3.5ba
Sulfhydryl group ( SH)
Thiol
(may be written HS )
Cysteine, a sulfur-
containing amino acid
Figure 3.5ba Some biologically important chemical groups (part 7: sulfhydryl) 13

14. Phosphate group ( OPO32–)
Figure 3.5bb
Phosphate group ( OPO32–)
Organic phosphate
Glycerol phosphate, which
takes part in many important
chemical reactions in cells
Figure 3.5bb Some biologically important chemical groups (part 8: phosphate) 14

15. component of DNA that has been modified by addition of a methyl group
Figure 3.5bc
Methyl group ( CH3)
Methylated compound
5-Methyl cytosine, a
component of DNA that has
been modified by addition of
a methyl group
Figure 3.5bc Some biologically important chemical groups (part 9: methyl) 15

16. ATP: An Important Source of Energy for Cellular Processes
One organic phosphate molecule, adenosine triphosphate (ATP), is the primary energy-transferring molecule in the cell
ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups
Adenosine
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17. Reacts with H2O Adenosine Adenosine Energy ATP Inorganic phosphate ADP
Figure 3.UN03
Reacts
with H2O
Adenosine
Adenosine
Energy
ATP
Inorganic
phosphate
ADP
Figure 3.UN03 In-text figure, ATP to ADP reaction, p.44 (upper right) 17

18. The first three of these can form huge molecules called macromolecules
Critically important molecules of all living things fall into four main classes
Carbohydrates
Lipids
Proteins
Nucleic acids
The first three of these can form huge molecules called macromolecules
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19. Concept 3.2: Macromolecules are polymers, built from monomers
A polymer is a long molecule consisting of many similar building blocks
Prefix poly: Many
These small building-block molecules are called monomers
Prefix mono: one
Some molecules that serve as monomers also have other functions of their own
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20. The Synthesis and Breakdown of Polymers
Cells make and break down polymers by the same process
A dehydration reaction occurs when two monomers bond together through the loss of a water molecule
Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction
These processes are facilitated by enzymes, which speed up chemical reactions
Animation: Polymers
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21. (a) Dehydration reaction: synthesizing a polymer
Figure 3.6a
(a) Dehydration reaction: synthesizing a polymer
Short polymer
Unlinked monomer
Dehydration removes
a water molecule,
forming a new bond.
Figure 3.6a The synthesis and breakdown of polymers (part 1: dehydration)
Longer polymer 21

22. (b) Hydrolysis: breaking down a polymer
Figure 3.6b
(b) Hydrolysis: breaking down a polymer
Hydrolysis adds
a water molecule,
breaking a bond.
Figure 3.6b The synthesis and breakdown of polymers (part 2: hydrolysis) 22

23. Concept 3.3: Carbohydrates serve as fuel and building material
Carbohydrates include sugars and the polymers of sugars
The simplest carbohydrates are monosaccharides, or simple sugars
Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks
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24. Sugars
Monosaccharides have molecular formulas that are usually multiples of CH2O
Glucose (C6H12O6) is the most common monosaccharide
Monosaccharides are classified by the number of carbons in the carbon skeleton and the placement of the carbonyl group
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25. product of glucose in cells
Figure 3.7
Triose: 3-carbon sugar (C3H6O3)
Pentose: 5-carbon sugar (C5H10O5)
Glyceraldehyde
An initial breakdown
product of glucose in cells
Ribose
A component of RNA
Hexoses: 6-carbon sugars (C6H12O6)
Figure 3.7 Examples of monosaccharides
Glucose
Fructose
Energy sources for organisms 25

26. Though often drawn as linear skeletons, in aqueous solutions many sugars form rings
Monosaccharides serve as a major fuel for cells and as raw material for building molecules
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27. (a) Linear and ring forms
Figure 3.8
(a) Linear and ring forms
Figure 3.8 Linear and ring forms of glucose
(b) Abbreviated ring structure 27

28. This covalent bond is called a glycosidic linkage
A disaccharide is formed when a dehydration reaction joins two monosaccharides
This covalent bond is called a glycosidic linkage
Animation: Disaccharides
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29. Glucose Fructose Figure 3.9-1
Figure Disaccharide synthesis (step 1) 29

30. Glucose Fructose 1–2 glycosidic linkage Sucrose Figure 3.9-2
Figure Disaccharide synthesis (step 2)
Sucrose 30

31. Polysaccharides
Polysaccharides, the polymers of sugars, have storage and structural roles
The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages
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32. Storage Polysaccharides
Starch, a storage polysaccharide of plants, consists entirely of glucose monomers
Plants store surplus starch as granules
The simplest form of starch is amylose
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33. Glycogen is a storage polysaccharide in animals
Humans and other vertebrates store glycogen mainly in liver and muscle cells
Animation: Polysaccharides
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34. Figure 3.10
Starch granules
in a potato tuber cell
Starch (amylose)
Glucose
monomer
Glycogen granules
in muscle
tissue
Glycogen
Cellulose microfibrils
in a plant cell wall
Cellulose
Cellulose
molecules
Hydrogen bonds
between —OH groups
(not shown) attached to
carbons 3 and 6
Figure 3.10 Polysaccharides of plants and animals 34

35. Structural Polysaccharides
The polysaccharide cellulose is a major component of the tough wall of plant cells
Like starch and glycogen, cellulose is a polymer of glucose, but the glycosidic linkages in cellulose differ
The difference is based on two ring forms for glucose
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36. (b) Starch: 1–4 linkage of  glucose monomers
Figure 3.11
(a)  and  glucose
ring structures
 Glucose
 Glucose
Figure 3.11 Monomer structures of starch and cellulose
(b) Starch: 1–4 linkage of  glucose monomers
(c) Cellulose: 1–4 linkage of  glucose monomers 36

37. (a)  and  glucose ring structures  Glucose  Glucose Figure 3.11a
Figure 3.11a Monomer structures of starch and cellulose (part 1: ring structures)
 Glucose 37

38. Starch (and glycogen) are largely helical
In starch, the glucose monomers are arranged in the alpha () conformation
Starch (and glycogen) are largely helical
In cellulose, the monomers are arranged in the beta () conformation
Cellulose molecules are relatively straight
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39. (b) Starch: 1–4 linkage of  glucose monomers
Figure 3.11b
(b) Starch: 1–4 linkage of  glucose monomers
Figure 3.11b Monomer structures of starch and cellulose (part 2: starch linkage) 39

40. (c) Cellulose: 1–4 linkage of  glucose monomers
Figure 3.11c
(c) Cellulose: 1–4 linkage of  glucose monomers
Figure 3.11c Monomer structures of starch and cellulose (part 3: cellulose linkage) 40

41. In straight structures (cellulose), H atoms on one strand can form hydrogen bonds with OH groups on other strands
Parallel cellulose molecules held together this way are grouped into microfibrils, which form strong building materials for plants
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42. Some microbes use enzymes to digest cellulose
Enzymes that digest starch by hydrolyzing  linkages can’t hydrolyze  linkages 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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43. 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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44. Concept 3.4: Lipids are a diverse group of hydrophobic molecules
Lipids do not form true polymers
The unifying feature of lipids is having little or no affinity for water
Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds
The most biologically important lipids:
fats
phospholipids
steroids
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45. Fats
Fats are constructed from two types of smaller molecules: glycerol and fatty acids
Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon
A fatty acid consists of a carboxyl group attached to a long carbon skeleton
Animation: Fats
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46. (in this case, palmitic acid)
Figure 3.12
Fatty acid
(in this case, palmitic acid)
Glycerol
(a) One of three dehydration reactions in the synthesis of a fat
Ester linkage
Figure 3.12 The synthesis and structure of a fat, or triacylglycerol
(b) Fat molecule (triacylglycerol) 46

47. (in this case, palmitic acid)
Figure 3.12a
Fatty acid
(in this case, palmitic acid)
Glycerol
Figure 3.12a The synthesis and structure of a fat, or triacylglycerol (part 1: dehydration reaction)
(a) One of three dehydration reactions in the synthesis of a fat 47

48. Fats separate from water because water molecules hydrogen-bond to each other and exclude the fats
In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride
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49. (b) Fat molecule (triacylglycerol)
Figure 3.12b
Ester linkage
Figure 3.12b The synthesis and structure of a fat, or triacylglycerol (part 2: a triacylglycerol molecule)
(b) Fat molecule (triacylglycerol) 49

50. Unsaturated fatty acids have one or more double bonds
Fatty acids vary in length (number of carbons) and in the number and locations of double bonds
Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds
Solid at room temperature
Source: animals. Ex: butter
Unsaturated fatty acids have one or more double bonds
Liquid at room temperature
Source: plants. Ex: vegetable oil
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51. (a) Saturated fat (b) Unsaturated fat Structural formula of a
Figure 3.13
(a) Saturated fat
(b) Unsaturated fat
Structural
formula of a
saturated fat
molecule
Structural
formula
of an
unsaturated
fat molecule
Space-filling
model of
stearic acid,
a saturated
fatty acid
Figure 3.13 Saturated and unsaturated fats and fatty acids
Space-filling
model of oleic
acid, an
unsaturated
fatty acid
Double bond
causes bending. 51

52. 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
Phospholipids are major constituents of cell membranes
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53. (a) Structural formula (b) Space-filling model (c) Phospholipid symbol
Figure 3.14
Choline
Hydrophilic head
Phosphate
Glycerol
Fatty acids
Hydrophobic tails
Hydrophilic
head
Figure 3.14 The structure of a phospholipid
Hydrophobic
tails
(a) Structural formula
(b) Space-filling model
(c) Phospholipid
symbol
(d) Phospholipid
bilayer 53

54. When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the interior
This feature of phospholipids results in the bilayer arrangement found in cell membranes
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55. 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
Video: Cholesterol Space Model
Video: Cholesterol Stick Model
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56. Figure 3.15
Figure 3.15 Cholesterol, a steroid 56