1. Chapter 02
Chemistry of Life

2. Levels of Chemical Organization and Chemical Bonding
Lesson 2.1
Levels of Chemical Organization and Chemical Bonding
Define the term and describe the structure of an atom.
Define the terms element, molecule, and compound.
Compare and contrast the major types of chemical bonding.

3. Na Elements Matter The substances from which the universe is made
All of the different types of matter
Identified by names or chemical symbols
Also identified by number
Described and organized in the periodic table 11
Sodium Na
22.99

4. What is the symbol and number for carbon?

5. Elements (cont.) Living matter contains 26 of 92 natural elements.
96% of body weight—four elements
4% of body weight—nine elements
0.1% of body weight—13 elements
The body’s chemical composition by weight.

6. Levels of Chemical Organization
Atom—smallest unit of matter
Nucleus—central core of atom
Proton—positively charged particle in nucleus
Neutron—uncharged particle in nucleus
Atomic number—number of protons in nucleus
Atomic mass—number of protons and neutrons combined

7. Atoms
Energy levels—orbital regions surrounding atomic nucleus that contain electrons
Electron—negatively charged particle
Each region has space for a specific number of electrons.
The first energy level has room for two electrons.
The second energy level has room for eight electrons.
An atom is most stable when its energy levels are filled with electrons.
Energy level increases the farther away it is from the nucleus

8. Models of the Atom

9. Elements (cont.) Energy Levels (cont.)
Hydrogen
Carbon
Total number of electrons 1 6
Number of electrons in first energy level 2
Number of electrons in second energy level 4
Energy Levels (cont.)
Hydrogen has only one energy level with room for one more electron.
Carbon’s first energy level is full.
Carbon’s second energy level has room for four more electrons.

10. Isotopes and Radioactivity (cont.)
Examples
Isotope
Proton Number
Neutron Number
Atomic Weight
Carbon-12 6 12
Carbon-13 7 13
Carbon-14 8 14
Isotopes
Forms of an element that have the same atomic number but different atomic weight
Different atomic weight because of a different number of neutrons
May be stable or unstable (radioactive)

11. Elements, Molecules, and Compounds
Element—a pure substance; made up of only one kind of atom
Molecule—a group of atoms chemically bound together in a group
Compound—substances whose molecules have more than one kind of atom

12. Name
Symbol
Function
Oxygen O
Part of water; needed to metabolize nutrients for energy
Carbon C
Basis of all organic compounds; component of carbon dioxide, the gaseous byproduct of metabolism
Hydrogen H
Part of water, participates in energy metabolism; determines the acidity of body fluids
Nitrogen N
Present in all proteins, ATP (the energy-storing compound), and nucleic acids (DNA and RNA)
Calcium Ca
Builds bones and teeth; needed for muscle contraction, nerve impulse conduction, and blood clotting
Phosphorus P
Active ingredient in ATP; builds bones and teeth; component of cell membranes and nucleic acids
Potassium K
Active in nerve impulse conduction; muscle contraction
Sulfur S
Part of many proteins
Sodium Na
Active in water balance, nerve impulse conduction, and muscle contraction
Iron Fe
Part of hemoglobin, the compound that carries oxygen in red blood cells
The elements are listed in decreasing order by weight in the body.

13. Chemical Bonding Chemical bonds form to make atoms more stable.
Atoms react with one another in ways that make their outermost energy level full.
Atoms may share electrons or donate or borrow them to become stable.

14. Ionic Bonds
Ions form when an atom gains or loses electrons in its outer energy level to become stable
Positive ion—has lost electrons; indicated by superscript positive sign(s), as in Na+ or Ca++
Negative ion—has gained electrons; indicated by superscript negative sign(s), as in Cl–

15. Ionic Bonds
Ionic bonds form when positive and negative (oppositely charged) ions attract each other
Electrolyte—molecule that dissociates (breaks apart) in water to form individual ions; an ionic compound

16. Ionic Bonding

17. Covalent Bonds
Covalent bonds form when atoms share their outer energy ions to complete the energy level and thus become stable.
Covalent bonds do not ordinarily easily dissociate in water.
Covalent bonding is used to form all of the major organic compounds found in the body.

18. Covalent Bonding

19. Hydrogen Bonds Hydrogen bonds do not create new molecules.
Hydrogen bonds weakly bond to neighboring molecules.
Hydrogen bonds are present in water, DNA, and proteins. .

20. Hydrogen Bonds

21. Inorganic and Organic Chemistry
Lesson 2.2
Inorganic and Organic Chemistry
Distinguish between organic and inorganic chemical compounds.
Discuss the chemical characteristics of water.
Explain the concept of pH.
Discuss the structure and function of the following types of organic molecules: carbohydrate, lipid, protein, and nucleic acid.

22. Inorganic Chemistry
Organic molecules contain carbon-carbon covalent bonds and/or carbon-hydrogen covalent bonds; inorganic molecules do not.
Organic molecules are generally larger and more complex than inorganic molecules.

23. Water Water is an inorganic compound essential to life.
Water is a solvent (liquid into which solutes are dissolved), forming aqueous solutions in the body.

24. Mixtures
Mixtures- consists of two or more substances that are mixed together but not chemically bonded and each ingredient keeps its own properties
Type
Definition
Example
Solution
Homogeneous mixture formed when one substance (solute) dissolves in another (solvent)
Table salt (NaCl) dissolved in water; table sugar (sucrose) dissolved in water
Suspension
Heterogeneous mixture in which one substance is dispersed in another but is not chemically bonded and will settle out unless constantly mixed
Red blood cells in blood plasma; milk of magnesia
Colloid
Heterogeneous mixture in which the suspended particles remain evenly distributed based on the small size and opposing charges of the particles
Blood plasma; cytosol

25. Mixtures (cont.) The Importance of Water
Most abundant compound in body
Critical in all physiologic processes
Deficiency (dehydration) threatens health
Universal solvent
Stable liquid at ordinary temperatures
Participates in body’s chemical reactions

26. Water Water is involved in chemical reactions: Dehydration synthesis
Hydrolysis
Chemical reactions always involve energy transfers, as when energy is used to build ATP molecules
Chemical equations show how reactants interact to form products; arrows separate the reactants from the products

27. Water-based Chemistry

28. Acids, Bases, and Salts Acid A substance that releases hydrogen ions
A substance that releases hydroxide ions and accepts hydrogen ions
Salt
A substance formed by a reaction between an acid and a base
HCl  H+ + Cl−
NaOH  Na+ + OH−
HCl + NaOH  NaCl + H2O

29. Acids, Bases, and Salts
Water molecules dissociate to form equal amounts of H+ (hydrogen ion) and OH– (hydroxide ion)
Acid—substance that shifts the H+/OH– balance in favor of H+; opposite of base
Base—substance that shifts the H+/OH– balance against H+; also known as an alkaline; opposite of acid

30. Acids, Bases, and Salts (cont.)
The pH Scale
Measures the relative concentrations of hydrogen and hydroxide ions in a solution.
Scale from 0 (most acidic) to 14 (most basic).
Each unit represents a 10-fold change.
Normal body fluid pH range is between 7.35 and 7.45.
Acidosis: Body fluid pH less than 7.35
Alkalosis: Body fluid pH greater than 7.45

31. pH
pH—Mathematical expression of relative H+ concentration in an aqueous solution
7 is neutral (neither acid nor base)
pH values above 7 are basic; pH values below 7 are acidic

32. pH Neutralization occurs when acids and bases mix and form salts.
Buffers form chemical systems that absorb excess acids or bases and thus maintain a relatively stable pH (proteins, Bicarbonate, or hemoglobin).

33. Organic Chemistry Carbohydrates—sugars and complex carbohydrates
Contain carbon (C), hydrogen (H), and oxygen (O)
Monosaccharides—basic unit of carbohydrate molecules (for example, glucose)
Disaccharide—double sugar made up of two monosaccharide units (for example, sucrose, lactose)
Polysaccharide—complex carbohydrate made up of many monosaccharide units (for example, glycogen; stored by the body)

34. Carbohydrates

35. Lipids—Fats and Oils Triglycerides
Formed by a glycerol unit and joined to three fatty acids
Store energy for later use

36. Phospholipids
Similar to triglyceride structure, but have phosphorus-containing units—each with a head and two tails
The head attracts water (hydrophilic) and the double tail does not (hydrophobic), thus forming stable double layers (bilayers) in water
Form membranes of cells

37. Phospholipids

38. Cholesterol
Molecules have a steroid structure made up of multiple rings
Stabilizes the phospholipid tails in cellular membranes
Also converted into steroid hormones by the body

39. Proteins
Very large molecules made up of amino acids held together in long, folded chains by peptide bonds
Structural proteins
Form essential structures of the body
Collagen is a fibrous protein that holds many tissues together
Keratin forms tough, waterproof fibers in the outer layer of the skin

40. Protein

41. Functional Proteins Participate in chemical processes of the body
Examples include hormones, cell membrane channels and receptors, and enzymes
Enzymes—chemical catalysts
Help chemical reactions occur
Enzyme action sometimes called lock-and-key model

42. Enzyme Action

43. Nucleic Acids Made up of nucleotides A phosphate unit
A sugar (ribose or deoxyribose)
A nitrogen base (adenine, thymine or uracil, guanine, cytosine)

44. DNA (Deoxyribonucleic Acid)
Used as the cell’s “master code” for assembling proteins
Uses deoxyribose as the sugar and A, T (not U), C, and G as bases
Forms a double helix shape

45. DNA

46. RNA (Ribonucleic Acid)
Used as a temporary “working copy” of a gene (portion of the DNA code)
Uses ribose as the sugar and A, U (not T), C, and G as bases

47. ATP (Adenosine Triphosphate)

48. Key Terms acid chemistry ion salt amino acid colloid isotope solute
anion
compound
lipid
solution
aqueous
denaturation
molecule
solvent
atom
electrolyte
nucleotide
steroid
base
electron
neutron
substrate
buffer
element pH
suspension
carbohydrate
enzyme
protein
catalyst
glucose
proton
cation
glycogen
radioactive

49. Word Anatomy (cont.) Word Part Meaning Example Chemical Bonds co-
together
Covalent bonds form when atoms share electrons.
Solutions and Suspensions
aqu/e
water
In an aqueous solution, water is solvent.
heter/o-
different
Heterogeneous solutions are different (not uniform) throughout.
hom/o-
same
Homogeneous mixtures are the same throughout.
hydr/o
Dehydration is a deficiency of water.
phil
to like
Hydrophilic substances “like” water—they mix with or dissolve it.
phobia
to fear
Hydrophobic substances “fear” water—they repel and do not dissolve it.

50. Word Anatomy (cont.) Word Part Meaning Example Organic Compounds -ase
suffix used in naming enzymes
A lipase is an enzyme that acts on lipids.
de-
remove
Denaturation of a protein removes its ability to function (changes its nature).
di-
twice, double
A disaccharide consists of two simple sugars.
glyc/o-
glucose, sweet
Glycogen is a storage form of glucose. It breaks down to release glucose.
mon/o-
one
In a monosaccharide, “mono-” refers to one.
poly-
many
A polysaccharide consists of many simple sugars.
sacchar/o
sugar
A monosaccharide consists of one simple sugar.
tri-
three
Triglycerides have one fatty acid attached to each of three carbon atoms.