1. Chemical Basis for Life
And Biochemistry

2. Chemistry of Life
Chemistry is important to biologists because all of the life activities in our cells that keep us alive are the result of chemical reactions.
Matter—anything that has mass and takes up space.
Elements—found on Periodic Table. Cannot be broken down into simpler kinds of matter.
HONC (Honk)—hydrogen, oxygen, nitrogen, carbon. These are the most important elements in living things.

3. Atoms
Atom—simplest particle of an element that keeps all the properties of that element.
Parts of an atom
Protons—positive charge
Neutrons—no charge
Electrons—negative charge
Inside Nucleus
Orbit Nucleus

4. The atomic number is the number of protons in an atom
The atomic mass is the number of protons plus the number of neutrons.
The number of electrons in an atom is the same as the number or protons giving it a net charge of zero.

5. Isotopes
Isotopes—atoms of the same element with different number of neutrons.

6. Compounds
Compounds —atoms of two or more elements joined by chemical bonds.
Examples: H2O NaCl C6H12O6
Three models below show a water molecule
Electron Cloud model
Stick model
Bohr model

7. Chemical Bonds
Chemical bonds are attractive forces that hold atoms together. They form so that elements can become more stable by filling their outer energy levels.

8. Types of Chemical Bonds
Covalent Bonds—two atoms SHARE electrons

9. Carbon has the ability to form multiple covalent bonds
Carbon has 4 electrons in its outer shell. The shell can hold 8. Carbon needs 4 more electrons to become stable. This can result in big biological molecules based around chains of carbon atoms.

10. Double —share 2 pair of electrons Triple —share 3 pair of electrons
Many complex biological molecules will be formed using double and triple covalent bonds.
Double —share 2 pair of electrons
Triple —share 3 pair of electrons
Ethane
Ethylene
Acetylene

11. Ionic Bonds—atoms LOSE or GAIN electrons creating charges that attract each other.
SALTS!!!!

12. Energy and Chemical Reactions
Chemical reactions occur when one or more substances change to produce one or more new substances.
Chemical equations show what happens during the reaction
Reactants on left Products on right
6CO H2O C6H12O O2 +energy

13. Reaction Speed
Most reactions need the addition of energy before they will begin.
Activation Energy —energy required for a reaction to begin
Catalyst —speed up chemical reactions by lowering the activation energy required.
Enzymes are common catalysts in living things
They remain unchanged throughout the reaction.

14. Endothermic and Exothermic Reactions
Endothermic reactions result in a net absorption of energy
Exothermic reactions results in the net release of energy

15. Oxidation Reduction Reactions
Also called Redox Reactions
Electrons are transferred between atoms
Oxidation reaction —a reactant loses electrons resulting in a positive charge
Example—Na loses an electron to become more stable creating a sodium ion (Na+)
Reduction reaction —a reactant gains electrons resulting in a negative charge
Example—Chlorine gains an electron to become more stable creating a chlorine ion (Cl-)
The two always occur together. One reactant gives up what the other needs.

16. Water and Solutions
Water’s chemical structure is important in its vital role in life.

17. Properties of Water Water is POLAR
Electrons in the covalent bond are not shared equally. Results in a partial negative charge on the oxygen end and a partial positive charge on the hydrogen end.

18. Being polar allows water to:
Dissolve many substances
Form hydrogen bonds with other water molecules creating:
Cohesion
Surface Tension
Adhesion
Capillarity
High heat capacity
Less density when water freezes (ice floats!!)

19. Solutions
Solution —mixture in which one or more substances are uniformly distributed in another substance.
Solute —dissolved substance
Solvent —substance in which the solute is dissolved
Concentration —amount of solute dissolved in a fixed amount of solution
Saturated Solution —no more solute can be dissolved

20. Ionization of Water
Water molecules can collide and break each other apart
H2O H OH-
OH- is known as the hydroxide ion
Free H+ ions react with water molecules:
H+ + H2O H3O+
H3O+ is known as the hydronium ion

21. Acids and Bases
Acid —solution in which the number of hydronium ions is greater than the number of hydroxide ions
They have a value BELOW 7 on the pH scale.
Base —solution in which the number of hydroxide ions is greater than the number of hydronium ions (Alkaline)
They have a value ABOVE 7 on the pH scale

22. Biochemistry Carbon—element of life
Organic compounds—contain carbon (and hydrogen)
Can form 4 covalent bonds with other elements so it is the backbone of all organic compounds.

23. Functional Groups
Various functional groups can be attached to these carbon backbones. These groups determine how these molecules will react with other molecules.
Functional groups can be seen on the following chart:

24. Functional Group
Structural Formula
Example
Hydroxyl
(Alcohols)
-OH H
Carbonyl (on end)
(Aldehydes)
- C=O
Carbonyl (in middle)
(Ketone) O C
Carboxyl
(Organic Acids)
COOH
Amino
(Amino Acids)
NH2
Phosphate
(Nucleic Acids)
PO43-

25. Large Carbon Molecules
The building of large molecules occurs as follows:
Monomers —small, simple carbon molecules
Polymers —consists of repeated, linked monomers
Macromolecules —large polymers:
(Carbohydrates, lipids, proteins, nucleic acids)

26. Condensation Reactions
Polymers form during condensation reactions
In these reactions; water is released

27. Example: Glucose and Fructose combine to form Sucrose

28. Hydrolysis Polymers break down by a hydrolysis reaction
In these reactions; water is used

29. The Energy Molecule: ATP
Adenosine Triphosphate (ATP ) —the most important energy currency molecule of cells.
Made of Adenine; Ribose (a sugar) and 3 phosphate groups

30. The Hydrolysis of ATP is used by the cell to provide the energy needed to drive chemical reactions.
-ATP can lose its end phosphate which releases the energy stored in it.
and makes adenosine diphosphate (ADP).
-This energy is used to do work in the cell.
-Adding the phosphate back to make ATP requires that we add energy

31. The Molecules of Life Four main groups of organic compounds:
Carbohydrates
Proteins
Lipids
Nucleic Acids

32. Carbohydrates Used for energy Three types:
Monosaccharides (glucose and fructose)
Disaccharides (sucrose)
Polysaccharides (glycogen, starch and cellulose)
Structure is too complex to show

33. Proteins Made of chains of amino acids held together by peptide bonds.
Dipeptides (two amino acids)
Polypeptides (long chains of amino acids) that fold and bend into proteins.
Typical amino acid

34. Form by condensation
reactions.

35. Enzymes —special types of proteins that act as catalysts

36. Lipids Lipids are fats. Used for energy Nonpolar
Fatty acids bonded to other molecules

37. Saturated Fatty Acids —each carbon is covalently bonded to four atoms (NO DOUBLE BONDS)
Unsaturated Fatty Acids —not all carbons are bonded to four other atoms (HAS DOUBLE BONDS)

38. Classes of Lipids
Triglycerides (fats) —three molecules of fatty acid joined to one molecule of glycerol.
Saturated triglycerides —the 3 fatty acids are saturated: hard at room temp: found in butter and red meat: “bad fats”
Unsaturated triglycerides —the 3 fatty acids are unsaturated: soft at room temp: found in plant seeds: “good fats”
Phospholipids —two fatty acids joined to glycerol. They also have a phosphate group.
Important part of all cell membranes
Waxes —fatty acid chain joined to an alcohol chain: waterproof: form protective layers in plants and animals
Steroids —four fused carbon rings with a functional group: include many hormones and cholesterol

39. Nucleic Acids Include DNA and RNA Information molecules
Made of repeating monomers called nucleotides.
Phosphate, pentose sugar, nitrogenous base.