Drew Smith :
Do bacteria have bacterium ? Yes .
We experience that bacterium order in size from 0.2micrometersto about onemillimeter . That ’s more than a thousand - fold conflict , easily enough to accommodate a small bacteria inside a larger one .
Nothing forbids bacterium from infest other bacteria , and in biology , that which is not forbidden is inevitable .
We have at least one example : Like many mealybugs , Planococcus citrihas a bacterial endosymbiont , in this type the β - proteobacteriumTremblaya princeps . And this endosymbiont in turn has the γ - proteobacteriumMoranella endobialivinginside it . See for yourself :
I do n’t have sex of examples of free - living bacteria hosting other bacteria within them , but that reflects either my ignorance or the likelihood that we have n’t look firmly enough for them . I ’m certain they are out there .
Most ( not all ) scientists studying the root of eukaryotic cellular phone believe that they are go down fromArchaea .
All scientists accept that the mitochondria which live inside eukaryotic cell are descendant of invasive alpha - proteobacteria . What ’s not exculpated is whether archeal cellphone became eukaryotic in nature — that is , acquired internal tissue layer and ecstasy system of rules — before or after acquiring mitochondria . The two scenario can be chalk out out like this :
The two hypotheses on the origin of eucaryote :
( A ) Archaezoan hypothesis .
( group B ) Symbiotic hypothesis .
The shapes within the eukaryotic jail cell denote the karyon , the endomembrane system , and the cytoskeleton . The irregular gray shape announce a putative rampart - less archaeon that could have been the host of the alpha - proteobacterial endosymbiont , whereas the oblong red shape denotes a distinctive archaeon with a mobile phone wall . A : archaea ; bacillus : bacterium ; E : eukaryote ; LUCA : last universal usual ancestor of cellular lifetime human body ; LECA : last eucaryotic common ancestor ; E - wicked : putative archaezoan ( primitive amitochondrial eukaryote ) ; E - mit : primitive mitochondrial eukaryote ; alpha : alpha - proteobacterium , ancestor of themitochondrion .
The Archaezoan surmisal has been given a minute of a boost by the discovery ofLokiarcheota . This complex Archaean has cistron for phagocytosis , intracellular tissue layer formation and intracellular transport and signaling — hallmark activity of eucaryotic cell . The Lokiarcheotan genes are clearly related to eukaryotic cistron , show a common ancestry .
Bacteria - within - bacteria is not onlynota gaga estimation , it probably accounts for the origin ofEucarya , and thus our own species .
We do n’t know how common this arrangement is — we mostly analyze bacteria these days by sequencing their DNA . This is great for observe uncultivatable metal money ( which are 99 percent of them ) , but does n’t state us whether they are free - living or are some kind of symbiont . For that , someone would have to spend a lot of time prepping environmental samples for close examination by microscopic method acting , a windy project indeed . But one well deserving doing , as it may shed more light on the history of liveliness — which is often a history ofconflictturned to cooperation . That ’s a level which never gets quondam or stale .
This post to begin with appeared on Quora . Clickhereto sight .
