This document provides an overview of the key biomolecules including carbohydrates, proteins, lipids, and nucleic acids. It describes how carbohydrates are made of monosaccharides that join to form disaccharides and polysaccharides. Proteins are made of amino acids that join in chains, and lipids include fatty acids, triglycerides, and phospholipids. The last section compares the nucleic acids DNA and RNA, which store and transport genetic information.

1. Section 2 Molecules of Life
Chapter 3
Objectives
• Distinguish between monosaccharides, disaccharides,and
polysaccharides.
• Explain the relationship between amino acids and protein
structure.
• Describe the induced fit model of enzyme action.
• Compare the structure and function of each of the different
types of lipids.
• Compare the nucleic acids DNA and RNA.

2. Section 2 Molecules of Life
Chapter 3
Carbohydrates
• Carbohydrates are organic compounds composed
of carbon, hydrogen, and oxygen in a ratio of about
one carbon to two hydrogen atoms to one oxygen
atom (1C:2H:1O)
• Carbohydrates are a source of energy and are used
as structural materials in organisms.

3. Section 2 Molecules of Life
Chapter 3
Carbohydrates
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4. Section 2 Molecules of Life
Chapter 3
Carbohydrates, continued
• Monosaccharides
– Carbohydrates are made up of monomers called
monosaccharides (or simple sugars).
– Contains carbon, hydrogen, and oxygen in a ratio
of 1:2:1
– General formula is (CH20)n

5. Monosaccharides
• The most common monosaccharides:
– Glucose – the main source of energy for cells
– Fructose – found in fruits and is the sweetest
monosaccharide
– Galactose – found in milk

6. Monosaccharides
• Glucose, fructose, and galactose have the same
molecular formula (C6H1206), but differing structures
• The different structures determine the slightly
different properties of the three compounds
• Isomers are compounds with the same chemical
formula but different structural forms

7. Section 2 Molecules of Life
Chapter 3
Carbohydrates, continued
• Disaccharides and Polysaccharides
– Two monosaccharides join in a condensation
reaction to form a double sugar called a
disaccharide.
– A complex sugar, or polysaccharide, is made of
three or more monosaccharides.

8. Polysaccharides
• Animals store • Plants store glucose
glucose as the as the
polysaccharide polysaccharide
glycogen starch
• Plants also make
the polysaccharide
cellulose (gives
strength and rigidity
to plant cells)

9. Section 2 Molecules of Life
Chapter 3
Disaccharides
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10. Section 2 Molecules of Life
Chapter 3
Proteins
• Proteins are organic compounds composed mainly
of carbon, hydrogen, oxygen, and nitrogen.
• Proteins have many functions including structural,
defensive, and catalytic roles.

11. Section 2 Molecules of Life
Chapter 3
Proteins, continued
• Amino Acids
– Proteins are made up of monomers called amino
acids. The sequence of amino acids determines a
protein’s shape and function.

12. Amino Acids
• There are 20 amino acids that all share a basic
structure
• Each amino acid contains a central carbon atom
covalently bonded to four other atoms or functional
groups
– A single hydrogen atom
– A carboxyl group
– An amino group
– R group

13. Section 2 Molecules of Life
Chapter 3
Amino Acids
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14. Section 2 Molecules of Life
Chapter 3
Proteins, continued
• Dipeptides and Polypeptides
– Two amino acids are joined by peptide bonds
through a condensation reaction to form a
dipeptide.
– A long chain of amino acids is called a
polypeptide.

15. Section 2 Molecules of Life
Chapter 3
Structure of Proteins

16. Section 2 Molecules of Life
Chapter 3
Proteins, continued
• Enzymes
– Enzymes speed up chemical reactions and bind
to specific substrates.
– The binding of a substrate with an enzyme causes
a change in the enzyme’s shape and reduces the
activation energy of the reaction.

17. Section 2 Molecules of Life
Chapter 3
Enzyme Activity

18. Enzymes
• To learn more about the function of enzymes, you are
going to do a virtual experiment
• PHSchool.com
• cbp-1024

19. Section 2 Molecules of Life
Chapter 3
Lipids
• Lipids are nonpolar molecules that store energy and
are an important part of cell membranes.

20. Section 2 Molecules of Life
Chapter 3
Lipids, continued
• Fatty Acids
– Most lipids contain fatty acids, unbranched
carbon molecules that have a hydrophilic end and
a hydrophobic end.

21. Section 2 Molecules of Life
Chapter 3
Fatty Acids
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22. Section 2 Molecules of Life
Chapter 3
Lipids, continued
• Triglycerides
– Triglycerides consist of three fatty acids and one
molecule of glycerol.

23. Section 2 Molecules of Life
Chapter 3
Lipids, continued
• Phospholipids
– Phospholipids, which make up cell membranes,
consist of two fatty acids and one glycerol
molecule.

24. Section 2 Molecules of Life
Chapter 3
Lipids, continued
• Waxes
– A wax is made of one long fatty acid chain joined
to one long alcohol.
• Steroids
– A steroid is composed of four fused carbon rings.

25. Section 2 Molecules of Life
Chapter 3
Nucleic Acids
• A nucleic acid is a large and complex organic
molecule that stores and transports information.

26. Section 2 Molecules of Life
Chapter 3
Structure of Nucleic Acids

27. Section 2 Molecules of Life
Chapter 3
Nucleic Acids
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28. Section 2 Molecules of Life
Chapter 3
Nucleic Acids, continued
• The nucleic acid deoxyribonucleic acid (DNA)
contains genetic information for cell activities.
• Ribonucleic acid (RNA) molecules play many key
roles in building of proteins and can act as enzymes.