1. Chemical Reaction
A chemical reaction occurs when new bonds are formed or old bonds break between atoms
The starting substances of a chemical reaction are known as reactants.
The ending substances of a chemical reaction are the products.

2. Chemical Reaction
Synthesis - anabolism - building molecules (Ex. – growth & repair)
Decomposition - catabolism - breaking molecules down (Ex. – digestion)
Exchange – buffers (Ex. Acids & bases)
Reversible - goes in both directions depending on the conditions

3. Chemical Reactions Synthesis: A + B  AB Decomposition – AB  A + B
Exchange – AB + CD  AD + CB
Reversible =

5. Elements
Substance that can neither be created nor destroyed by ordinary means.
Three forms
Solid, liquid, gas
92 elements found naturally
Additional elements have been man made

6. The Element Song by Tom Lehrer

7. Ions, Molecules, and Compounds
If an atom either gives up or gains electrons, it becomes an ion - an atom that has a positive or negative charge due to having unequal numbers of protons and electrons.
When two or more atoms share electrons, the resulting combination is called a molecule
When atoms of different elements bond, they form compound

8. Ions, Molecules and Compounds
A compound is a substance that can be broken down into two or more different elements by ordinary chemical means.
Useful compounds
H2O (Water)
HCl (hydrogen chloride)
NaCl (Salt)
C6H12O6 (Sugar)
NaHCO3 (sodium bicarbonate or baking powder)
CO2 (carbon dioxide)

9. Types of Compounds Inorganic
Made of molecules that do not contain carbon
Couple exceptions
Carbon dioxide
Calcium carbonate
Water is inorganic and comprises between 55% and 65% of human body weight
Water is the most important inorganic compound

10. Water
Water is needed for regulation of body temperature at 37o C. (Sweat)
Water is also a very good solvent.
Held together by hydrogen bonds.

11. Organic Compounds Organic
Always contain carbon, combined with hydrogen
More than a million known organic compounds
Inorganic molecules are smaller than organic
Four main groups
Carbohydrates, lipids, proteins, nucleic acids

12. Molecules Smallest unit of a compound
Capable of its own independent existence
Example: water can be broken down into smaller droplets.

13. Acid-Base Balance: The Concept of pH
Body fluids must constantly contain balanced quantities of acids and bases.
Biochemical reactions are very sensitive to even small changes in acidity or alkalinity.
Ex. BP or breathing rate
A solution’s acidity or alkalinity is based on the pH scale, which runs from ) (=100 = 1.0 moles H+/L) to 14 (= = moles H+/L) (Fig. 2.14)

14. Acid-Base Balance: The Concept of pH
pH 7.0 = 10-7 = moles H+/L = neutrality or equal numbers of [H+] and [OH-].
Values below 7 indicate acid solutions ([H+] > [OH-]).
Values above 7 indicate alkaline solutions ([H+] < [OH-]).
Examples: NaCl = Na+ + Cl- (electrolyte)
HCl = H+ + Cl- (acid)
NaOH = Na+ + OH- (base)

15. Maintaining pH: Buffer Systems
The pH values of different parts of the body are maintained fairly constant by buffer systems, which usually consist of a weak acid and a weak base.
The function of a buffer system is to convert strong acids or bases into weak acids or bases.

16. Maintaining pH: Buffer Systems
One important buffer system in the body is the carbonic acid-bicarbonate buffer system.
It is one of the major buffering systems used to maintain the pH of mammalian blood.
It is used in the formation of acid in the lumen on the stomach.
It is used to neutralize the pH of the chyme leaving the stomach and entering the small intestine.
Bicarbonate ions (HCO3-) act as weak bases and carbonic acid (H2CO3) acts as a weak acid.

18. Carbohydrates Carbon, hydrogen, and oxygen
Monosaccharides (building block)
Sugars that can not be broken down
Glucose, fructose, galactose, ribose, deoxyribose (DNA)
Glucose main source of energy
Stored in the blood (glycogen)

19. Disaccharides Double sugar
Formed by dehydration synthesis (loss of water molecule)
Also formed by hydrolysis (addition of water)
Must be broken down by digestion (hydrolysis) to monosaccharides in order to be absorbed by the body.

20. Polysaccharides Complex molecules Starch, cellulose, glycogen
Broken down to Disaccharides and then monosaccharides
Potatoes, plant tissue

21. Terminology Di – two Saccharide – containing C,H,O
Disaccharide – two sugars
Extra – outside
Intra – inside
Mono – one
Uni - one

22. Lipids Contain carbon, hydrogen, oxygen
Different to CHO’s; they have less oxygen in relation to hydrogen.
Fats, phospholipids, steroids, waxes, oils
Fats – triglycerides
Building Block – fatty acid and a glycerol
Phospholipids – C,H,O and phosphorus
Steroids - cholesterol

24. Proteins Organic compounds Contain Carbon, Hydrogen, Oxygen, Nitrogen
Most diverse and essential
Found in every part of the living cell
Binding and structural components.
20 different Amino Acids (building block)

25. Enzymes Specialized proteins Control various chemical reactions
Provide energy
Organic catalyst
Affects the rate or speed of a chemical reaction without itself being changed.
Enzymes usually end in –ase
Specific for a substrate

28. Nucleic Acids Carbon, hydrogen, oxygen, hydrogen, nitrogen, phosphorus
Subunits called nucleotides
Phosphate, sugar, nitrogen base
Purines
Adenine (A) and Guanine (G)
Pyrimidines
Cytosine (C) and Thymine (T)
Example: DNA and RNA