Chapter 2 On-Line Lesson - Biological Chemistry




BIO 190: The Class: Chemistry of Life: Lesson 2

Biological Chemistry

Water Facts and Characteristics

Water is the most abundant compound in cells. Water has several unique properties that equip it for its essential role in living organisms.

Water has:

-a high specific heat capacity
-a high heat of vaporization
-highest density at 4 degrees C while stills a liquid
-high surface tension (figure 2-3)
-low viscosity
-excellent solvent properties (figure 2-4)
-a major role in many chemical reactions in living organisms
-hydrolysis
-condensation.

Water and pH

Water spontaneously ionizes to a slight degree. The pH of a solution describes the hydrogen ion concentration. The pH of distilled water is 7, which is considered neutral pH. Acids have pH values of less than 7 and bases have alkaline pH values of greater than 7. Try the interactive pH scale below which shows the pH values for some common substances.

Organic Molecules

The term "organic molecule" is currently used in a broad sense to apply to compounds that contain carbon. The ability of carbon to form bonds with other carbon atoms in chains in a multitude of configurations allows great opportunities for complexity at the molecular level.

Large Molecule Review

Macromolecules

Examples of organic molecules include the following major categories.

Carbohydrates

Green plants from water and carbon dioxide synthesize carbohydrates. This process, known as photosynthesis, is one on which all life depends.

Carbohydrates are divided into three classes:

-monosaccharides (simple sugars)

-disaccharides (double sugars)

-polysacaccharides (complex sugars)

Lipids

Lipids are fats and fatlike substances, characterized by low polarity.

As such they are insoluble in water.

Examples of lipids are:

-neutral fats
-saturated
-unsaturated
-phospholipids
-steroids (figure 2-12)

Proteins

Browse through the Protein Chemistry site below before proceeding. Also, be sure to open any links provides further down in the outline.

Protein Chemistry

Proteins are large and complex molecules made up of 20 amino acids. (figure 2-13). Amino Acids

Proteins are highly organized molecules. Biochemists refer to them in terms of four levels of organization or structures. (figure 2-14).

Primary Structures

-determined by the kind of sequence of amino acids

Secondary Structures

-recurrent structural patterns assumed by the chain
-often an alpha-helix.

Tertiary Structures

-the three-dimensional form resulting form folding and bending of the helices
-folded chains are stabilized by interactions between groups of amino acids, such as: -disulfide bonds
-hydrogen bonds
-ionic bonds
-hydrophobic bonds

Browse the sites below for additional information.

Chemistry Central

Chem Web

Quaternary Structure

-used to describe proteins with more than one polypeptide chain unit.

The Role of Proteins as Enzymes

Although proteins perform many functions, their most important role is as enzymes. Enzymes are biological catalysts, which are required for just about every reaction in living things.

Chapter 5

Protein Chemistry

Nucleic Acids

Nucleic acids are complex molecules that encode, via their nitrogenous bases, the genetic information that is the framework for all life. The two kinds of nucleic acids in cells are

-deoxyribose nucleic acid (DNA)

DNA Graphics Gallery

-ribose nucleic acid (RNA).

These nucleic acids are made up of repeated units of nucleotides, each of which contains a sugar, a nitrogenous base and a phosphate group.

Once you have completed the lesson, you should go to Assignment 2-1.

E-mail the professor W. Sylvester Allred at Syl.Allred@NAU.EDU, or call (520)523-7214