Introduction to Bioinformatics
This textbook is a solid introduction to the science of Bioinformatics, an integration of computing skills and biological methods.
TABLE OF CONTENTS Introduction to Bioinformatics
Chapter 2: Genome Organization and Evolution
Genomics and proteomics
The genome of a typical bacterium comes as a single DNA molecule, which, if extended, would be about 2 mm long. (The cell itself has a diameter of about 0.001 mm.) The DNA of higher organisms is organized into chromosomes - normal human cells contain 23 chromosome pairs. The total amount of genetic information per cell - the sequence of nucleotides of DNA - is very nearly constant for all members of a species, but varies widely between species (see Box for longer list):
| Organism | Genome size |
|---|---|
| Epstein-Barr virus | 0.172 10 6 base pairs |
| Bacterium ( E. coli) | 4.6 10 6 |
| Yeast ( S. cerevisiae) | 12.1 10 6 |
| Nematode worm ( C. elegans) | 95.5 10 6 |
| Thale cress ( A. thaliana) | 117.0 10 6 |
| Fruit fly ( D. melanogaster) | 180.0 10 6 |
| Human ( H. sapiens) | 3200 10 6 |
Not all DNA codes for proteins. Conversely, some genes exist in multiple copies. Therefore, the amount of protein sequence information in a cell cannot easily be estimated from the genome size.
Genes
A single gene coding for a particular protein corresponds to a sequence of nucleotides along one or more regions of a molecule of DNA. The DNA sequence is collinear with the protein sequence. In species for which the genetic material is double-stranded DNA, genes may appear on either strand. Bacterial genes are continuous regions of DNA. Therefore, the functional unit of genetic...
Copyright Arthur M. Lesk 2002 under license agreement with Books24x7
