Microbial Genetics

The science of genetics began with the work of Gregor Mendel, an Austrian monk, as early as the middle of the 19th century. Mendel's experiments with selective cross- breeding of pea plants established the fundamental principles of heredity. He described certain laws of inheritance and showed that certain physical characteristics called traits, such as flower colour, seed colour, seed shape, stem length, and so on, are passed on from generation to generation; some traits called recessive are masked by dominant traits and most traits are inherited independently of others. For example, pea flowers are either purple or white, and intermediate colours do not show up upon cross-breeding.

However, Mendel's findings remained unnoticed till the 20th century when geneticists experimenting on fruit flies recognized his work; it was shown that there are genes in chromosomes. Specific genetic alterations could also be linked to the change of physical characteristics of the organism, that is, genotype–phenotype relations could be established. However, the bacterial genetics studies were the first to bring in the chemical nature of the gene as well as the mechanisms by which the genotype determines the phenotype.

The journey began with the breakthrough in the 1940s which showed that bacteria can be a genetic tool, and since then many of the principles of genetics as well as recombinant DNA technology have been developed around bacteria. Escherichia coli was the primary focus in all these studies, and some of the genetically useful bacterial viruses called bacteriophages were also involved in elucidating genetic principles. It may be recalled that the first genome to be sequenced completely was a bacterial genome. Although the sequencing of E. coli genome was started before, the credit of the first genome to be sequenced goes to Haemophilus inßuenzae. Understanding the principles of bacterial and bacteriophage genetics is therefore extremely important and needs to be emphasized for understanding the areas of molecular biology and recombinant DNA technology.

1. Basic Molecular Genetics: DNA Structure, Replication, and Repair

2. Basic Molecular Genetics: Gene Expression and Relation

3. Methods of Genetic Analysis

4. Conjugation

5. Transformation

6. Transduction

7. Techniques for Studying Bacteriophages

8. Plasmids

9. Generic Rearrangements and their Evolutionary Significance

10. Recombinant DNA Technology

11. Construction of DNA Libraries

12. Protein Expression in Bacteria

13. Sequencing of DNA and Proteins

14. Synthesis of Oligonucleotides

15. Site-specific Mutagenesis

16. Protein Engineering

17. Gene Isolation and Synthesis

18. Polymerase Chain Reaction

19. DNA Fingerprinting and Footprinting

20. RARP, RFLP, and AFLP

21. Restriction Mapping

22. Application of Recombination DNA Technology

23. Containment and Ethics in Genetic Engineering