1. Chapter 2
Chemical Basis of Life

2. Basis of Life 2.1
Although there is an almost endless variety of living things on Earth, most living things are made of four kinds of chemicals----Carbohydrates, Lipids, Proteins and Nucleic Acids.

3. Carbohydrates
An organic compound composed of carbon, hydrogen, and oxygen atoms, stores energy and provides shape or structure to organisms.

4. Lipids
An organic compound commonly referred to as fats, oils and waxes; tends to be insoluble in water.
When energy is to be stored for an even longer period of time, carbohydrates are converted into a different chemical—fat, a type of lipid.

5. Fats and Oil Provide long term energy storage
Act as insulation by helping to keep animals warm.

6. Wax Repel water Plants use it to keep water in and prevent drying out.
Ducks and other waterfowl use to waterproof feathers.

7. Phosopholipids
These molecules form the membrane or protective covering that surrounds cells.
Help control substance that enter or leave the cell.

8. Proteins A complex macromolecule composed of amino acids
½ the dry weight of a body is made of protein.
Organisms use only 20 amino acids to make proteins.

9. Different combinations of amino acids produce different proteins

10. Enzymes One group of proteins that helps control chemical reactions.
Can increase the speed of a reaction by a millionfold.

11. Nucleic Acid
A large, complex DNA or RNA molecule that carries hereditary, or genetic, information
DNA—deoxyribonucleic Acid, carries instructions that control the activities of the cell.
RNA---ribonucleic Acid, uses DNA instructions to make proteins.

12. Element 2.2
A substance that cannot be broken down by chemical processes into simpler substances.
Four elements are especially abundant in the human body.
Oxygen 65%, Carbon 18.5%, Hydrogen 9.5% and Nitrogen 3.5%.

13. What are the simplest chemical parts of living organism?
Atoms
Molecules

14. Atoms Atoms are the building blocks of elements. Atoms are made up of:
Smallest unit of an element with the properties of that element.
Atoms are the building blocks of elements.
Atoms are made up of:
Protons (p+) Positive Charge
Neutrons (n0) -- No Charge (Neutral)
Electrons (e-) -- Negative Charge

15. Atoms Electrons (e- ) Protons (p+ ) Nucleus Energy Levels
All atoms have the same general arrangement.
Electrons (e- )
Protons (p+ )
Nucleus
Energy Levels
Neutrons (n0 )

16. Atoms # of Protons is constant for an element.
# of Protons = # of Electrons ~ Zero Charge
# of Protons is constant for an element.
e.g. Hydrogen = 1 Oxygen = 8 Carbon = 6
# Protons = Atomic Number
# of Neutrons is NOT constant for all elements.
Isotopes -- nuclei unstable, break apart and give off radiation ~ can damage or kiss cells, e.g., radioactive isotopes of cobalt and iodine used in treating cancer and detecting problems in thyroid, respectively
Different numbers = ISOTOPES.
Radioisotopes ~ isotopes with UNSTABLE nuclei
Some, not all, are radioactive, e.g., Carbon -14.

17. What happens when a chemical compound breaks down?
The bonds between the elements in the compound break. The elements can form other compounds , or they can remain as pure elements.

18. Compound
Two or more elements chemically combined in definite proportions.
CO2
H2O

19. Organic Compounds
A compound that contains carbon; usually associated with living things.
Does not include carbonates or chlorates.
CH3COCH3---Acetone

20. Ion An atom that has lost or gained electrons.
What is the charge of Electron, Neutron, and proton?
O-2 oxygen has gained two electrons
Na+1 Sodium has lost one electron

21. Isotopes
One of several atoms of the same element that have the same number of protons but different numbers of neutrons.
Lead-204 (A)
Lead-206 (A)
Lead-207 (A)
Lead-208 (A)

22. Chemical Bond
A force that holds two or more atoms together.

23. Ionic Bond
Chemical bond formed from the attractive force between two ions of opposite charge.
One + and one –
Generally a metal reacting with a non-metal.
NaCl

24. Covalent Bond
Chemical bond in which the electrons are not gained or lost, but shared.
- with a –
Usually two non-metals
CO2

25. Ionic Bond One atom is left with a positive charge.
One atom loses an electron and one atom gains an electron -- crystal is formed.
One atom is left with a positive charge.
One atom is left with a negative charge.
Opposite charges hold atoms together. e-
Na Cl Na+ + Cl-

26. Covalent Bonds H20 molecule Atomic # O = 6 Atomic # H = 1 e- e- Oxygen
Atoms share electrons, e.g.
H20 molecule e- e-
Oxygen e-
Atomic # O = 6
Atomic # H = 1 e- e- e- e- e-
Max # electrons = 2 n2
Shell 1 = 2 electrons
Shell 2 = 8 electrons
Shell 3 = 18 electrons
Shell 4 = 32 electrons
s = 2 electrons
p = 6 electrons
d = 10 electrons
f = 14 electrons e- e-
Hydrogen
Hydrogen

27. Covalent Bonds Atomic # O = 6 Atomic # H = 1
Equal Sharing -- Nonpolar Molecule
Unequal Sharing -- Polar Molecule e- e-
Oxygen e-
Atomic # O = 6
Atomic # H = 1 e- e-
Negative Charge e- e- e- e- e-
Positive Charge
Hydrogen
Hydrogen
Water is the one essential life-giving substance!

28. Polar Molecules
In some covalent bonds, the atoms do not share the electrons evenly, leave one end more positive and the other end more negative.
Water is a polar molecule.

29. Chemical Reaction
A reaction characterized by the breaking or forming of chemical bonds.

30. What are some examples of chemical reactions?
Rusting
Bleaching
Burning
Souring

31. What are chemical bonds?
Forces that hold two or more atoms together.

32. Enzyme
A catalytic protein that speeds up the chemical reactions within an organism.

33. Substrate
The reactant or substance to be changed.

34. How an enzyme works.
The region on the enzyme where the substrate attaches is called the enzymes active site.
At the active site, the substrate is changed slightly by the enzyme so a specific chemical bond is weakened.
The weakened bond allows the substrate to break apart quickly.

35. What are some important life processes in which chemical reactions occur?
Digestion
Respiration
Transformation of energy
Excretion
Immune response

36. Metabolism
The sum of all the chemical processes that occur within an organism.
Turns the proteins, lipids and carbohydrates into energy that your cells needs and uses.

37. Homeostasis
The maintenance of a stable set of internal conditions within an organism.
Like an internal balance system.
It takes millions of chemical reactions to keep the internal conditions of living things stable.

38. What occurs during metabolism?
The chemical changes that occur in the organism are coordinated, allowing the cells of the organism to obtain and use the energy.

39. Why is maintaining stable internal conditions important to living things?
To sustain life, internal conditions must remain constant and stable.

40. Why are chemical reactions important to an organism’s growth and repair?
Chemical reactions take place to produce new cells for growth and to replace injured or diseased cells.

41. Solution A uniform mixture of two or more substances.
Water solutions are important since all of life’s chemical processes occur in solutions
Most ionic compounds dissolve in water.

42. Solute The part of a solution that gets dissolved.
The sugar in sugar water.

43. Solvent The part of a solution that does the dissolving
The water in sugar water.

44. Water Known as universal solvent
Has Cohension, “sticking together” produces surface tension. This is why it hurts when you belly flop, or why some bugs can run across water.
Expansion—when liquid water freezes it expands and thus changes it density. This is not expected.

45. Acids and Bases
pH -- a measure of how acidic or basic (alkaline) a substance is (scale 0-14).
Acid -- any substance that forms hydrogen ions (H+) in water
Example: HCl H+ + Cl-
pH < 7
Base -- any substance that forms hydroxyl ions (OH-) in water
Example: NaOH Na+ + OH-
pH > 7

46. pH of Common Solutions pH Acidic Neutral Basic 1 2 3 4 5 6 7 8 9 10 111 2 3 4 5 6
Neutral 7 8 9 10 11 12 13
Basic 14

47. pH Scale
The standard measurements of the concentrations of hydrogen ions.
7 is neutral
7-14 base
0-7 is an acid

48. Why is water referred to as the universal solvent?
It forms solutions readily

49. What happens when water is added to acid?
Hydrogen ions are released.

50. What occurs when water is added to a base?
Hydroxide ions are released.

51. Bonding Patterns Covalent Bonds Ionic Bonds Hydrogen Bonds
two atoms share one or more pairs of electrons
Ionic Bonds
one atom loses an electron, one atom gains an electron ~ results in negative and positive ions which are attracted to one another
Hydrogen Bonds
a chemical bond in which a hydrogen atom of one molecule is attracted to an electronegative atom, especially nitrogen, oxygen, or fluorine

52. Hydrogen Bonds These bonds give water its unique properties.
Positive ends of polar molecules are attracted to negative ends of other polar molecules.
Bonds form, break, reform frequently.
Bonds are weak (1/20 covalent bond).
These bonds give water its unique properties.
H Bonds - + + + +
Covalent Bonds + - - + +

53. Acids and Bases
pH -- a measure of how acidic or basic (alkaline) a substance is (scale 0-14).
Acid -- any substance that forms hydrogen ions (H+) in water
Example: HCl H+ + Cl-
pH < 7
Base -- any substance that forms hydroxyl ions (OH-) in water
Example: NaOH Na+ + OH-
pH > 7

54. pH of Common Solutions pH Acidic Neutral Basic 1 2 3 4 5 6 7 8 9 10 111 2 3 4 5 6
Neutral 7 8 9 10 11 12 13
Basic 14

55. Review “QUIZ”
The center of an atom is called the
nucleus
Atoms of the same element with different numbers of neutrons are called
isotopes
Any substance that forms hydrogen ions (H+) in water is called a(n)
acid
Atoms of two or more elements chemically combined are
compounds
Two atoms that share electrons are held together by bonds.
covalent

56. Review “QUIZ” polar molecule
A molecule with an unequal distribution of charge is a
polar molecule
A mixture in which one substance is distributed evenly in another is a
solution
Any substance that forms hydroxyl ions (OH-) in water is called a(n)
base
When one atom loses an electron and another atom gains the electron, the atoms are held together by
ionic bonds
The one essential life-giving substance is
water