1. Chapter 2: Chemicals of Life

2. A. Bonding 1. Covalent Bonds
2 or more atoms share electrons to form a molecule
No net charge due to equal number of + and –
Ex. water

3. Covalent bonding vs. Hydrogen bonding
Properties of Water
Covalent bonding vs. Hydrogen bonding
Hydrogen Bond
Covalent Bond

4. A. Bonding
2. Hydrogen Bonds
Weak bond between polar molecules

5. A. Bonding 3. Ionic Bonds Gained or lost one or more electrons
Charged due to unequal number of electrons or protons
Ex. NaCl

6. B. Properties of Water 1. High Heat Capacity Water heats slow
Retains heat longer
Helps maintain homeostasis

7. Water is the solvent of Life!
B. Properties of Water
2. Universal Solvent
Water is the solvent of Life!
Solute – substance dissolved in a solvent to form a solution
Solvent – fluid that dissolves solutes
Example: Ice Tea – water is the solvent and tea and sugar the solutes

8. 3. Cohesion, Adhesion and Surface Tension
B. Properties of Water
3. Cohesion, Adhesion and Surface Tension
a. cohesion = water attracted to other water
molecules because of polar properties
ex. Forms drops or film
surface tension = water is pulled together creating the smallest surface area possible
b. adhesion = water attracted to other materials
ex. Getting wet, capillary action

9. B. Properties of Water
4. Capillary Action = Water molecules move due to adhesive and cohesive properties as a result of the original adhesion.
Ex: Think water in a straw
Ex: Water moves through trees this way

10. B. Properties of Water 5. Water is a polar molecule.
Many substances will dissolve
Non-polar molecules will not dissolve

11. C. Classes of Organic Molecules:
What are the four classes of organic molecules?
Carbohydrates
Lipids
Proteins
Nucleic Acids

12. 1. Carbohydrates Sugars Carbo = carbon, hydrate = water; Oxygen
Functions:
Store energy in chemical bonds
Glucose is the most common monosaccharide
Monosaccharides
Disaccharides
Polyshaccharides

13. 1. Carbohydrates
Benedicts Test

14. 1. Carbohydrates
Iodine
Starch test

15. 2. Lipids Structure: Greasy or oily nonpolar compounds Functions:
Energy storage
membrane structure
Protecting against drying out.
Insulating against cold.
Absorbing shocks.

16. 2. Lipids Saturated and Unsaturated Fats
liquid at room temp
one or more double bonds between carbons in the fatty acids allows for “kinks” in the tails
most plant fats
Saturated fats:
have only single C-C bonds in fatty acid tails
solid at room temp
most animal fats

17. 2. Lipids.
Phospholipids
Structure: Glycerol + 2 fatty acids + phosphate group.
Function: Main structural component of membranes, where they arrange in bilayers.

18. 3. Proteins Structure: Polypeptide chains
Consist of peptide bonds between 20 possible amino acids
Have a 3 dimensional globular shape

19. 3. Functions of Proteins Enzymes speed up a chemical reaction
Structural materials
keratin (the protein found in hair and nails)
collagen (the protein found in connective tissue)
Specific carriers –
Carry materials across cell membrane, carry oxygen in blood

20. 3. Proteins: Structure of Amino Acid Hydrogen Amino group
Carboxyl (acid) group
Variable R group specific to each amino acid

21. 4. Nucleic Acids Two kinds: DNA: RNA: double stranded
can self replicate
makes up genes which code for proteins
is passed from one generation to another
RNA:
single stranded
functions in actual synthesis of proteins coded for by DNA
is made from the DNA template molecule