Answer to Question #140257 in Genetics for subash

Question

Many scientists involved in the history of an important organic chemical which have a
complex molecular structure that can be found in all prokaryotic and eukaryotic cells and
important for identification and classification of an organism.

Explain the component of the organic chemical and how we account the differences
between species of an organism if it is made of the same component.

Answer 1

Deoxyribonucleic acid, DNA is a molecule composed of a deoxyribose sugar that forms the backbone, a phosphate group and four nitrogenous bases that is Adenine, Guanine, Cytosine and Thymine (A,G,C,T, respectively). Two of the bases, Adenine and Guanine are classified as purine molecules, a chemical with a double bring structure while both Cytosine and Thymine are pyrimidines, with a single ring structure.

Collectively, DNA exists as a sequence of nucleotides, nitrogenous bases that coil around each other to form a double helix structure which is a carrier for genetic instructions, for instance, growth, reproduction, functionality and development of organisms.

To resolve between two organisms with the same sequence, scientists compare the sequences of nucleotides to determine mutations at specific locations of the DNA molecule, in most cases the locations that are highly variable or with higher rates of mutations.

These sequences can then be used to construct phylogenetic trees to classify organisms into various groups. It is a robust technique that has the capability of resolving up to subspecies level of organization of organisms and besides gives room for classifying organisms that can not be isolated and cultured in cheap and available growth medium in commercial aboratories.