DNA AND RNA BASED TAXONOMY OF ANIMALS
- 1. MOLECULAR TAXONOMY DNA AND RNA BASED TAXONOMY OF ANIMALS DONE BY: NIVETHA.M 1stYEAR M.Sc,Zoology
- 2. INTRODUCTION • Molecular Taxonomy is the classification of organisms on the basis of the distribution and composition of chemical substances in them. • Molecular techniques in the field of biology have helped to establish genetic relationship between the members of different taxonomic categories . • The data obtained from such studies are used to construct phylogenetic trees. • Fitch and Margoliash ,(1967) made first phylogenetic tree based on molecular data . • This tree was so close to the already established phylogenetic trees of the vertebrates that the taxonomists realized significance of molecular data.
- 3. CONT.. • DNA and protein sequencing, immunological methods, DNA-DNA or DNA-RNA hybridization methods are more informative in the study of different species. The data obtained from are used to construct phylogenetic trees.
- 4. DNA CLASSIFICATION • Classification of organisms into closely related species. • Embryology is also used to identify similar structures in early development of animals. • Biochemical similarities can be used to identify closely related organisms.
- 5. SAMPLING • The biological material to be identified is collected. DNA EXTRACTION • DNA is extracted from the cells of the Specimen.
- 6. FINDING A SUITABLE GENE • The DNA used to identify differences and similarities between organisms must be evaluated. • These data gives details whether the organism is nearly identical within a species or not and show differences between those species.
- 7. Finding the individual’s code • The sequence of bases (GATC) in the gene is found then.
- 8. Identification of the species • The sequence of bases is then compared with a standard sequence to identify the species. • An international library of base sequences is developing to allow scientists across the world to compare their specimens.
- 9. RNA CLASSIFICATION • m RNA - ( messenger RNA ) these are the RNA’s that encode polypeptide chains. • r RNA - (ribosomal RNA) these from the core structure of the ribosome. • t RNAs – (transfer RNA) these are used by the ribosome to translate the tri-nucleotide. • sn RNA – (smaller nuclear RNA) these form the core components of the Splicesome an enzyme that catalyses the splicing mRNA.
- 10. TAXONOMICAL STUDIES BY USING MODERN METHODS Methods Explanation Hybridization Genetic materials from two different species is subjected to hybridize. Closely related species show higher percentage of hybridization DNAsequencing DNA segments of two species are sequenced from one end to the other and the sequences of the two form the basis of establishing similarity or dissimilarity between them Restriction mapping Segments of DNA are isolated from different species and subjected to restriction mapping. Closely related species will have more similar restriction map Chromosome banding The chromosomes of different species are examined through microscope. Banding of chromosomes are also done for taxonomic purposes Amino acid sequencing Like DNA sequencing protein sequencing is also done. The amino acid sequence of a given protein will be more similar between closely related species.