Evolution is driven by environmental that put selection pressure on organisms. a. What environments lead to the development of an \'open\' pan-genome? What conditions lead to a \'closed\' pan-genome? b. Why do bacteria of a single species have genes that other members of the same species do not? Solution Pan genome is the entire set of genes of all the strains of a species it includes genes present in all the strains and the dreams present only in some strains. Pan genome can be defined as open or closed based on the capability of the species to acquire exogenous DNA and to possess large amount of rRNA. These species with open pangenome tend to have large genome and contain open genes where there is high rate of genes transfer and several ribosomal Operon. Some bacterial species may have unlimited large genes repertoire or open pangenome and other species may have limited by maximum number of genes in their gene pool called closed pangenome. In open Pan genome species the number of genes of The species increases with the number of additionally sequence d strrains species which live in multiple environment of different microbial communities have chances for exchanging genetic material and hence continuously changed a set of genes example E.coli. In closed pangenome after some sequenced strains additional strains don\'t provide new genes to the species this pangenome is typical for species that live in isolated niches with Limited access to global microbial genen pool example bacillus anthracis. B. For example different strains of the pathogen pseudomonas syringae have different host range and their remarkably have different genomes due to differences in the virulence genes in their genomes. The ecological niche determines the evolution of the gene content of an organism that for the largest genomic differences observed among the strains of a species could be the outcome of Differential evolution of those species in response to different ecological habitats..

1. Evolution is driven by environmental that put selection pressure on organisms. a. What
environments lead to the development of an 'open' pan-genome? What conditions lead to a
'closed' pan-genome? b. Why do bacteria of a single species have genes that other members of
the same species do not?
Solution
Pan genome is the entire set of genes of all the strains of a species it includes genes present in all
the strains and the dreams present only in some strains. Pan genome can be defined as open or
closed based on the capability of the species to acquire exogenous DNA and to possess large
amount of rRNA. These species with open pangenome tend to have large genome and contain
open genes where there is high rate of genes transfer and several ribosomal Operon.
Some bacterial species may have unlimited large genes repertoire or open pangenome and other
species may have limited by maximum number of genes in their gene pool called closed
pangenome.
In open Pan genome species the number of genes of The species increases with the number of
additionally sequence d strrains species which live in multiple environment of different microbial
communities have chances for exchanging genetic material and hence continuously changed a set
of genes example E.coli.
In closed pangenome after some sequenced strains additional strains don't provide new genes to
the species this pangenome is typical for species that live in isolated niches with Limited access
to global microbial genen pool example bacillus anthracis.
B. For example different strains of the pathogen pseudomonas syringae have different host range
and their remarkably have different genomes due to differences in the virulence genes in their
genomes. The ecological niche determines the evolution of the gene content of an organism that
for the largest genomic differences observed among the strains of a species could be the outcome
of Differential evolution of those species in response to different ecological habitats.