Signature sequences are highly conserved sequences which are largely same in all bacteria . It differs significantly in case of eukaryotes and also in some large bacteria groups .These are contiguous patterns of amino acids 10-50 residues long that are associated with a particular structure or function in proteins. These may be of three types (by our nomenclature): superfamily signatures, remnant homologies, and motifs.
The differences in the oligonucleotide ssequences are found even within genera and species . One of the use of signature sequences in different proteins is to determine the relative branching order of bacterial divisions.The phylogenetic placement of the rumen bacterium Fibrobacter succinogenes was determined using a signature sequence approach that allows determination of the relative branching order of the major divisions among Bacteria.
Signature sequences in proteins, defined as conserved inserts or deletions that are restricted to specific taxa which provides a powerful means to deduce the evolutionary relationship among distantly related organisms .
Signature sequences in different proteins provide a means to define a number of different taxa within prokaryotes (namely, low G+C and high G+C gram-positive, Deinococcus-Thermus, cyanobacteria, chlamydia-cytophaga related, and two different groups of Proteobacteria) and to indicate how they evolved from a common ancestor. Based on phylogenetic information from indels in different protein sequences, it is hypothesized that all eukaryotes, including amitochondriate and aplastidic organisms, received major gene contributions from both an archaebacterium and a gram-negative eubacterium. In this model, the ancestral eukaryotic cell is a chimera that resulted from a unique fusion event between the two separate groups of prokaryotes followed by integration of their genomes.
The differences in the oligonucleotide ssequences are found even within genera and species . One of the use of signature sequences in different proteins is to determine the relative branching order of bacterial divisions.The phylogenetic placement of the rumen bacterium Fibrobacter succinogenes was determined using a signature sequence approach that allows determination of the relative branching order of the major divisions among Bacteria.
Signature sequences in proteins, defined as conserved inserts or deletions that are restricted to specific taxa which provides a powerful means to deduce the evolutionary relationship among distantly related organisms .
Signature sequences in different proteins provide a means to define a number of different taxa within prokaryotes (namely, low G+C and high G+C gram-positive, Deinococcus-Thermus, cyanobacteria, chlamydia-cytophaga related, and two different groups of Proteobacteria) and to indicate how they evolved from a common ancestor. Based on phylogenetic information from indels in different protein sequences, it is hypothesized that all eukaryotes, including amitochondriate and aplastidic organisms, received major gene contributions from both an archaebacterium and a gram-negative eubacterium. In this model, the ancestral eukaryotic cell is a chimera that resulted from a unique fusion event between the two separate groups of prokaryotes followed by integration of their genomes.
Q.The signature sequence is used extensively in-
(a) Cultivation of microorganisms
(b) Reclassification of misclassified organisms
(c) Defining of a specific group within a domain
(d) All of the above
(b) Reclassification of misclassified organisms
(c) Defining of a specific group within a domain
(d) All of the above
Ans. c
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