1. Chapter 3
Molecules of Life

2. Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #2
3.1 Organic Molecules
Organic Chemistry
Organic molecules contain carbon and hydrogen atoms.
Four classes of organic molecules (biomolecules) exist in living organisms:
Carbohydrates
Lipids
Proteins
Nucleic Acids 2

3. Inorganic versus Organic Molecules3

4. Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #4
Organic Chemistry
Biomolecules
Carbohydrates, lipids, proteins, and nucleic acids are called biomolecules.
Usually consist of many repeating units
Each repeating unit is called a monomer.
A molecule composed of monomers is called a polymer (many parts).
Example: amino acids (monomer) are joined together to form a protein (polymer) 4

5. © The McGraw Hill Companies, Inc./John Thoeming, photographer
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fig. 3.3
Biomolecules
Category
Subunit(s)
Polymer
Carbohydrates*
Monosaccharide
Polysaccharide
Lipids
Glycerol and fatty acids
Fat
Proteins*
Amino acids
Polypeptide
Nucleic acids*
Nucleotide
DNA,RNA
*Polymers
© The McGraw Hill Companies, Inc./John Thoeming, photographer

6. Synthesis and Degradation
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #6
Synthesis and Degradation
Organic Chemistry
A dehydration reaction is a chemical reaction in which subunits are joined together by the formation of a covalent bond and water is produced during the reaction.
Used to connect monomers together to make polymers
Example: formation of starch (polymer) from glucose subunits (monomer)
A hydrolysis reaction is a chemical reaction in which a water molecule is added to break a covalent bond.
Used to breakdown polymers into monomers
Example: digestion of starch into glucose monomers 6

7. dehydration reaction hydration reaction
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
monomer OH H
monomer
dehydration
reaction H O 2
monomer
monomer
a. Synthesis of a biomolecule
monomer OH H
monomer
hydration
reaction H O 2
monomer
monomer
b. Degradation of a biomolecule

8. Synthesis and Degradation
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #8
Synthesis and Degradation
Organic Chemistry
Enzymes are required for cells to carry out dehydration synthesis and hydrolysis reactions.
An enzyme is a molecule that speeds up a chemical reaction.
Enzymes are not consumed in the reaction.
Enzymes are not changed by the reaction. 8

9. 3.2 Carbohydrates Functions: Energy source
Provide building material (structural role)
Contain carbon, hydrogen and oxygen in a 1:2:1 ratio
Varieties: monosaccharides, disaccharides, and polysaccharides

10. Monosaccharides A monosaccharide is a single sugar molecule.
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #10
Organic Chemistry
Monosaccharides
A monosaccharide is a single sugar molecule.
Also called simple sugars
Have a backbone of 3 to 7 carbon atoms
Examples:
Glucose (blood), fructose (fruit) and galactose
Hexoses - six carbon atoms
Ribose and deoxyribose (in nucleotides)
Pentoses – five carbon atoms 10

11. Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #11
Organic Chemistry
Disaccharides
A disaccharide contains two monosaccharides joined together by dehydration synthesis.
Examples:
Lactose (milk sugar) is composed of galactose and glucose.
Sucrose (table sugar) is composed of glucose and fructose.
Maltose is composed of two glucose molecules. 11

12. + + dehydration reaction hydrolysis reaction glucose C6H12O6
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
dehydration reaction
hydrolysis reaction
glucose C6H12O6
glucose C6H12O6
maltose C12H22O11
water + +
monosaccharide
monosaccharide
disaccharide
water

13. Polysaccharides A polysaccharide is a polymer of monosaccharides.
Examples:
Starch provides energy storage in plants.
Glycogen provides energy storage in animals.
Cellulose is found in the cell walls of plants.
Chitin is found in the cell walls of fungi and exoskeleton of some animals.
Peptidoglycan is found in the cell walls of bacteria.

14. Amylose: nonbranched Amylopectin: branched
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Amylose:
nonbranched
starch
granule
Amylopectin:
branched
a. Starch
250 m
glycogen
granule
b . Glycogen
150 nm
a: © Jeremy Burgess/SPL/Photo Researchers, Inc.; b: © Don W. Fawcett/Photo Researchers, Inc.

15. 3.3 Lipids Lipids are varied in structure.
Large nonpolar molecules that are insoluble in water
Functions:
Long-term energy storage
Structural components
Cell communication and regulation
Protection
Varieties: fats, oils, phospholipids, steroids, waxes

17. Triglycerides: Long-Term Energy Storage
Also called fats and oils
Functions: long-term energy storage and insulation
Consist of one glycerol molecule linked to three fatty acids by dehydration synthesis

18. + H H H H H H H O H H H H H O 3 H2O C C C C C C H H C O C C C C C C H
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H H H H H H H O H H H H H O
3 H2O C C C C C C H H C O C C C C C C H H C OH HO H H H H H H H H H H H H H H H H H O H H H H H H H + O C C C C C C C C H H C H C C C C C C C C H H C OH HO H H H H H H H H H H H H H H H H H H O H H H O H H C C C C H C O
3 H2O C C C C H C C H C OH HO C C H H H H H H H H H H in in
glycerol
3 fatty acids
3 water
molecules
fat molecule a.
Formation of a fat

19. Triglycerides: Long-Term Energy Storage
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #19
Organic Chemistry
Triglycerides: Long-Term Energy Storage
Fatty acids are either unsaturated or saturated.
Unsaturated - one or more double bonds between carbons
Tend to be liquid at room temperature
Example: plant oils
Saturated - no double bonds between carbons
Tend to be solid at room temperature
Examples: butter, lard 19

20. Copyright © The McGraw-Hill Companies, Inc
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fig. 3.10 H H H H H H H O H H H H H O
3 H2O C C C C C C H H C O C C C C C C H H C OH HO H H H H H H H H H H H H H H H H H O H H H H H H H + O C C C C C C C C H H C H C C C C C C C C H H C OH HO H H H H H H H H H H H H H H H H H O H H H O H H C C C C H H C O C C C C H C
3 H2O C H C OH HO H H C C H H H H H H H H in in
glycerol
3 fatty acids
3 water
molecules
fat molecule a.
Formation of a fat
corn
corn oil H H H H H H H H H H H H H H H O C C C C C C C C C C C C C C C C C C H HO H H H H H H H H H H H H H
unsaturated fatty acid with double bonds (yellow)
unsaturated fat
mil
butter H H H H H H H H H H H H H H H O C C C C C C C C C C C C C C C C H HO H H H H H H H H H H H H H H H
saturated fatty acid with no double bonds
saturated fat b.
Types of fatty acids c.
Types of fats

21. Phospholipids: Membrane Components
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #21
Organic Chemistry
Phospholipids: Membrane Components
Structure is similar to triglycerides
Consist of one glycerol molecule linked to two fatty acids and a modified phosphate group
The fatty acids are nonpolar and hydrophobic.
The modified phosphate group is polar and hydrophilic.
Function: form plasma membranes
In water, phospholipids aggregate to form a lipid bilayer.
Polar phosphate heads are oriented towards the water.
Nonpolar fatty acid tails are oriented away from water.
Nonpolar fatty acid tails form a hydrophobic core. 21

22. Fig. 3.11 Phospholipids Form Membranes outside cell inside cell
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
glycerol O
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
Polar
Head
CH2
CH2
CH2
CH3 1
CH2 C O
fatty acids 2 O
CH2 O R O P O 3
CH2 C
CH2
CH2
CH2
CH2
CH2
CH2
CH2 CH CH O
CH2
Nonpolar Tails
CH2
phosphate
CH2
CH2 a.
Phospholipid structure
CH2
CH2
CH2
CH3
inside cell
outside cell
b. Plasma membrane of a cell .

23. Steroids: Four Fused Carbon Rings
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #23
Organic Chemistry
Steroids: Four Fused Carbon Rings
Composed of four fused carbon rings
Various functional groups attached to the carbon skeleton
Functions: component of animal cell membrane, regulation
Examples: cholesterol, testosterone, estrogen
Cholesterol is the precursor molecule for several other steroids. 23

24. Waxes Long-chain fatty acid bonded to a long-chain alcohol
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #24
Organic Chemistry
Waxes
Long-chain fatty acid bonded to a long-chain alcohol
Solid at room temperature
Waterproof
Resistant to degradation
Function: protection
Examples: earwax, plant cuticle, beeswax 24

25. Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #25
3.4 Proteins
Organic Chemistry
Proteins are polymers of amino acids linked together by peptide bonds.
A peptide bond is a covalent bond between amino acids.
Two or more amino acids joined together are called peptides.
Long chains of amino acids joined together are called polypeptides.
A protein is a polypeptide that has folded into a particular shape and has function. 25

26. Functions of Proteins Metabolism Support Transport Defense Regulation
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #26
Functions of Proteins
Organic Chemistry
Metabolism
Most enzymes are proteins that act as catalysts to accelerate chemical reactions within cells.
Support
Keratin and collagen
Transport
Hemoglobin and membrane proteins
Defense
Antibodies
Regulation
Hormones are regulatory proteins that influence the metabolism of cells.
Motion
Muscle proteins and microtubules 26

27. Amino Acids: Protein Monomers
There are 20 different common amino acids.
Amino acids differ by their R groups.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. C H R
acidic
group
amino
COOH
H2N
R = rest of molecule

28. Sample Amino Acids with Nonpolar (Hydrophobic) R Groups
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Sample Amino Acids with Nonpolar (Hydrophobic) R Groups H O H H O O H
H3N+ O C C
H3N+ C C
H3N+ C C H O O O
H3N+ O
CH2
H2N+ C C
(CH2)2
CH2 C C O O CH CH S
H2C
CH2
CH3
CH3
CH3
H3C
CH2
CH3
valine (Val)
methionine (Met)
phenylalanine (Phe)
leucine (Leu)
proline (Pro)
Sample Amino Acids with Polar (Hydrophilic) R Groups H O H O H O H O
H3N+ C C
H3N+ C C
H3N+ C C
H3N+ C C O O
CH2 O O CH
CH2
(CH2)2 SH OH C
cysteine (Cys)
serine (Ser) H O
NH2 O OH
glutamine (Gln)
H3N+ C C H O
tyrosine (Tyr) O
H3N+ C C
CH2 O CH C
NH2 O OH
CH3
asparagine (Asn)
threonine (Thr)
Sample Amino Acids with Ionized R Groups H O H O H O
H3N+ C C
H3N+ C C H H O O O
H3N+ C C
CH2
(CH2)3 O
H3N+ C C
H3N+ C C O O
CH2
CH2 O
CH2 NH
CH2 NH
CH2
CH2 C C
N+H2
COO-
N+H3 O O
NH2
N+H
glutamicacid (Glu)
lysine (Lys)
aspartic acid (Asp)
arginine (Arg)
histidine (His)

29. amino group acidic group peptide bond dehydration reaction
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
amino group
acidic group
peptide bond
dehydration reaction
hydrolysis reaction
amino acid
amino acid
water
dipeptide

30. Levels of Protein Structure
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #30
Levels of Protein Structure
Organic Chemistry
Proteins cannot function properly unless they fold into their proper shape.
When a protein loses it proper shape, it said to be denatured.
High temps, pH changes, and chemicals can denature a protein 30

31. 3.5 Nucleic Acids Nucleic acids are polymers of nucleotides.
Biology, 9th ed,Sylvia Mader
Chapter 03
Slide #31
3.5 Nucleic Acids
Organic Chemistry
Nucleic acids are polymers of nucleotides.
Two varieties of nucleic acids:
DNA (deoxyribonucleic acid)
Genetic material that stores information for its own replication and for the sequence of amino acids in proteins.
RNA (ribonucleic acid)
Perform a wide range of functions within cells which include protein synthesis and regulation of gene expression 31