Draft Sequence: (DNA draft Sequence): A Draft sequence of DNA is a sequence of bases in the DNA that may not be as accurate as that of the Complete sequence. In a draft sequence, there may be missing bases, or the sequence may be in the wrong order. The bases may not be in the correct orientation and their exact chromosomal location may not be known (not applicable for Prokaryotes). In the context of The Human Genome project, scientists mapped the order of base pairs in each chromosomal area at least 4 to 5 times (4x to 5x) to ensure data accuracy and to help with reassembling DNA fragments in their original order. This repeated sequencing is known as genome “depth of coverage.” Draft sequence data are mostly in the form of 10,000 base pair-sized fragments whose approximate chromosomal locations are known.

Finished Seqeunce (Finished DNA Sequence) : A DNA sequence in which the bases are identified to an accuracy of no more than 1 error in 10,000 and are placed in the right order and orientation along a chromosome with almost no gaps. A finished sequence is as opposed to a draft DNA sequence. In the context of the Human Genome Project, additional sequencing was done to close gaps, reduce ambiguities, and allow for only a single error every 10,000 bases, the agreed-upon standard for the HGP. Investigators believe a high-quality sequence is critical for recognizing gene-regulatory components important in understanding human biology and disorders such as heart disease, cancer, and diabetes. The finished version provides an estimated 8x to 9x coverage of each chromosome.

Microbiome: A microbiome is defined as the sum total of microorganisms along with their genomes present in a particular environment. This environment could be a sample of soil, water or even the human gut. This term was coined by Joshua Lederberg who acknowledged the profound impact of microbes on human health and physiology.

Microbiota: The term microbiota refers to the microbial flora of any particular environment.

Metagenomics: This is the study of the Genomes of bacteria recovered directly from environmental samples as a collective unit. Therefore there is no requirement of culturing individual organisms or obtaining pure cultures for the sake of genomic studies. The study could be function based ie genes are screened for their potential functions , or sequence based where emphasis is on obtaining sequence data. The term was coined by Jo Handelsman. The study employs a large number of latest techniques such as DNA Sequencing, Data analysis etc.

16S rRNA Sequencing: 16S rRNA is a part of the ribosomal RNA of Prokaryotic cells which is about 1542 Nucleotides long. It has been observed that this molecule contains regions which are highly conserved (not altered much due to mutation) among species. Thus if these molecules are sequenced and the sequences of various species are compared the microbes can be Phylogenetically classified. This is powerful tool used for Classification and Genome analysis.