1. Chemical Basis of Life Chapter 2
Chemistry - study of matter
Biochemistry-chemistry of organisms

2. 2.1: Introduction Why study chemistry in an
Anatomy and Physiology class?
- Body functions depend on cellular functions
- Cellular functions result from chemical changes
- Biochemistry helps to explain physiological processes

3. 2.2: Structure of Matter
Matter – anything that takes up space and has mass (weight). It is composed of elements.
Elements – composed of chemically identical atoms:
Bulk elements – required by the body in large amounts
Trace elements - required by the body in small amounts
Ultratrace elements – required by the body in very minute amounts
Atoms – smallest particle of an element

4. Structure of Matter A. Atoms-basic unit 1. Nucleus
a. proton- “+”, 1 amu
b. neutron- no charge, 1 amu
2. Energy Levels/Shells
a. electron- “-”, 0 amu
2,8,8

6. All atoms are electrically neutral because the # of p+ = # of e-.
Atomic number = # of protons.
Atomic weight = # of protons + neutrons.
Isotopes-atoms of the same element having different atomic masses.
Radioactive isotopes-an isotope which easily loses subatomic particles.

8. Molecules and Compounds
Molecule – particle formed when two or more atoms chemically combine
Compound – particle formed when two or more atoms of different elements chemically combine
Molecular formulas – depict the elements present and the number of each atom present in the molecule
H C6H12O H2O

9. Bonding of Atoms: Ions
Ion
An atom that gains or loses electrons to become stable
An electrically charged atom
Cation
A positively charged ion
Formed when an atom loses electrons
11p+
17p+
12n0
18n0
Anion
A negatively charged ion
Formed when an atom gains electrons
Sodium atom (Na)
Chlorine atom (Cl)
(a) Separate atoms
If a sodium atom loses an electron to a chlorine atom, the sodium
atom becomes a sodium ion (Na+), and the chlorine atom becomes
a chloride ion (Cl–).

11. Covalent Bonding
occurs when the atoms forming the bond SHARE one or more pairs of electrons
this results in MOLECULES
Each “dash” represents a pair of shared electrons (single covalent bond)

13. Bonding of Atoms: Structural Formula
Structural formulas show how atoms bond and are arranged in various molecules
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H H H H O O O O C O H2 O2
H2O
CO2

14. Bonding of Atoms: Polar Molecules
Molecule with a slightly negative end and a slightly positive end
Results when electrons are not shared equally in covalent bonds
Water is an important polar molecule
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Slightly negative end
(a)
Slightly positive ends

15. Hydrogen Bonds Hydrogen Bonds
A weak attraction between the positive end of one polar molecule and the negative end of another polar molecule
Formed between water molecules
Important for protein and nucleic acid structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H H O H
Hydrogen bonds O H H O H H O H H O H
(b)

17. Chemical Reactions
Chemical reactions occur when chemical bonds form or break among atoms, ions, or molecules
Reactants are the starting materials of the reaction - the atoms, ions, or molecules
Products are substances formed at the end of the chemical reaction
NaCl ’ Na+ + Cl-
Reactant
Products

18. Chemical Reactions SYNTHESIS - “A + B---> AB”
Ex: H2 + O2---> H2O
DECOMPOSITION - “AB ---> A + B”
Ex: 2H2O ---> 2H2 + O2
EXCHANGE - “AB + CD ---> AD + CB”
Ex: HCl + NaOH ---> NaCl + H2O
Many reactions are reversible
Ex: A + B <---> AB

19. Acids, Bases, and Salts NaCl  Na+ + Cl- HCl  H+ + Cl-
Electrolytes – substances that release ions in water
NaCl  Na+ + Cl-
Acids – electrolytes that dissociate to release hydrogen ions
in water
HCl  H+ + Cl-
Bases – substances that release ions that can combine with hydrogen ions
NaOH  Na+ + OH-
Salts – electrolytes formed by the reaction between an acid and a base
HCl + NaOH  H2O + NaCl

21. pH-measurement of the H+ concentration of a solution
0< >14
acidic alkaline
(basic)
distilled water is neutral, having a pH of 7.0
blood pH = 7.4
if below--->acidosis
if above--->alkalosis
pH scale ranges from

22. Figure 02.10

23. Organic -contain C & H Inorganic-don’t contain both C & H
Chemistry of Cells
Organic -contain C & H
Inorganic-don’t contain both C & H

24. 2.3: Chemical Constituents of Cells
Organic v. Inorganic Molecules
Organic molecules
Contain C and H
Usually larger than inorganic molecules
Dissolve in water and organic liquids
Carbohydrates, proteins, lipids, and nucleic acids
Inorganic molecules
Generally do not contain C
Usually smaller than organic molecules
Usually dissociate in water, forming ions
Water, oxygen, carbon dioxide, and inorganic salts

26. Organic Compounds Organic compounds almost always have covalent bonds.
The four types we will discuss are:

27. 1. Carbohydrates contain C, H, O---H:O ratio is 2:1
Ex: C6H12O C12H22O11
provide immediate energy source
short-term energy storage
carbon is in short chains or RINGS
Monosaccharides (simple sugars) examples are: glucose, fructose, galactose, ribose, deoxyribose

28. Disaccharides (double sugars): examples are sucrose, lactose, maltose
Disaccharides (double sugars): examples are sucrose, lactose, maltose. These are each made of 2 rings of carbons (2 simple sugars joined together.
Polysaccharides: examples are starch, glycogen (animal starch), and cellulose. These are made of many rings of carbon (many simple sugars joined together).

30. Figure 02.12

31. 2. Lipids provide long-term energy storage
water insoluble (either the entire molecule or part of the molecule)
cell structure, vitamins, hormones
types: fats, phospholipids, cholesterol

32. Fats (animal fats, oils)
made of C,H,&O, but H:O ratio is MUCH greater than 2:1 (C57H110O6)
Each molecule is called a triglyceride, and is made of 1 glycerol and 3 fatty acids.
An unsaturated fat has at least one carbon to carbon double or triple bond in its fatty acids, and it is usually liquid--good.
A saturated fat has no C=C or triple, usually solid--bad.

35. Phospholipids major component of cell membranes
Each molecule is made of 1 glycerol, 2 fatty acids, and 1 phosphoric acid
partially water insoluble

37. Cholesterol
important in cell membranes and as source of steroid hormones
partially water insoluble

39. 3. Proteins
structural component of cells, some hormones, transporters, enzymes
Each molecule is made of a LONG chain of amino acids. This chain takes on a 3-dimensional shape due to hydrogen bonding between the amino acids.
Denaturization-results from the breaking of H-bonds---alters shape--destroys function

46. Animation: Protein Denaturation
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47. 4. Nucleic Acids
DNA, RNA
made of chains of nucleotides--each nucleotide is made of: 5-C sugar, phosphate, and nitrogenous base
DNA-found in chromosomes-provides code for protein production (genes)
RNA-helps in protein production

49. Figure 02.21