1. Chapter 5:
Molecules of Life

2. Organic vs. Inorganic
All compounds may be classified into two broad categories:
organic compounds - carbon based molecules
inorganic compounds - almost all are non-carbon based molecules

3. 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)

4. Carbon Bonding Carbon can also bond with other carbon atoms
Forms three types of structures:
Straight chains
Branched chains
Rings

5. Carbon bonding
Carbon can share one, two or three electrons with another atom
single bond - one electron shared
double bond - two electrons shared
triple bond - three electrons shared

6. Macromolecules Large organic molecules. Also called POLYMERS.
Made up of smaller “building blocks” called MONOMERS.

7. How Are Macromolecules Formed?

8. Answer: Dehydration Synthesis
Also called “condensation reaction”
Forms polymers by combining monomers by “removing water”. HO H
H2O HO H

9. How are Macromolecules separated or digested?

10. Answer: Hydrolysis
Separates monomers by “adding water” HO H
H2O HO H

11. Macromolecules FOUR MAIN CATEGORIES:
1) carbohydrates: fuel & building material
2) lipids: fats & oils
3) proteins: perform most cell functions
4) nucleic acids: information storage (Chap. 11)
Made up of nucleotides
DNA & RNA
Forms the genetic code

12. Carbohydrates

13. Carbohydrates Carbohydrates are made of sugar molecules
Sugars contain carbon, hydrogen, and oxygen in the following ratio:
1 carbon : 2 hydrogen : 1 oxygen

14. 3 main types of carbohydrates:
Monosaccharide: one sugar unit
Ex: glucose, fructose, lactose
Disaccharide: two sugar units
Ex: Sucrose (glucose + fructose)
Ex: Galactose (glucose + lactose)
Polysaccharide: many sugar units;
Ex: Starch: found in plants (bread, tomatoes)
Ex: Glycogen: found in animal cells
Ex: Cellulose: found in cell wall of plants

15. Carbohydrates Most carbohydrates are polar and hydrophilic
Hydrophilic: attracted to water molecules
Monosaccharides and disaccharides easily dissolve in water to form sugar solutions

16. Lipids

17. Lipids Lipids are not soluble in water.
They are nonpolar and hydrophobic do not mix with water
Lipids “store the most energy”
Examples:
Fats, oils
Phospholipids
Steroid hormones
Triglycerides

18. 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)

19. Simplest Fats 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 =

20. Fatty Acids There are two kinds of fatty acids:
1. Saturated fatty acids: no double bonds (bad)
solid at room temperature, Ex: butter
2. Unsaturated fatty acids: at least 1 double bonds (good)
liquid at room temperature, Ex: Fruits, olive oil 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

21. Steroids Classified as lipids  are hydrophobic
Differ from fats in structure & function
Some act as chemical signals or hormones  estrogen and testosterone

22. Proteins

23. Functions of Proteins Form structures—hair, fur, muscles
Provide long-term nutrient storage
Circulate and defend the body against microorganisms (antibodies)
Act as chemical signals—hormones
Help control chemical reactions in cells—enzymes

24. Protein Structure
Proteins are polymers formed from monomers called amino acids.
Amino acids bonded together by peptide bonds (polypeptides).
There are 20 different kinds of amino acids.
aa1
aa2
aa3
aa4
aa5
aa6
Peptide Bonds
Amino Acids (aa)

25. Amino Acid Structure
Three of central carbon’s partners are the same in all of the 20 different amino acids
1. hydrogen atom
2. carboxyl group
3. amino group

26. Amino Acid Structure
Differences between one amino acid and another are due to the unique “R group” or side group that each one has
Each “R group” is responsible for a different chemical property for each amino acid

27. Protein Shape
Functional proteins consist of precisely twisted, coiled, and shaped polypeptides
Proteins cannot function correctly if shape is altered
Denaturation: loss of normal protein shape
Unfavorable changes in temperature, pH, or other environmental conditions may cause proteins to become denatured

28. Enzymes are proteins that speed up specific reactions in cells

29. Activation Energy
Activation energy: minimum energy required to start chemical reaction
Catalysts: compounds that speed up chemical reactions
Enzymes: proteins that act as catalysts for chemical reactions in organisms

30. How Enzymes Work ACTIVE SITE MODEL
Substrate: specific reactant acted on by an enzyme
Active site: specific region of the enzyme that the substrate fits into
Substrate binds to enzyme’s active site where the substrate undergoes a change