Irenaeus, Siteadmin, Check users, oversight, Administrators
351,726
edits
Changes
Jump to navigation
Jump to search
Line 2:
Line 2: + + + + + + + + + + + + +
no edit summary
the origins of [[mitochondria]], plastids (e.g. [[chloroplasts]]), and [[nuclei]] in [[eukaryotes|eukaryotic cells]]. According
the origins of [[mitochondria]], plastids (e.g. [[chloroplasts]]), and [[nuclei]] in [[eukaryotes|eukaryotic cells]]. According
to this theory, these organelles arose from free-living bacteria that were taken inside another cell as endosymbionts.
to this theory, these organelles arose from free-living bacteria that were taken inside another cell as endosymbionts.
== Creation science critique of the edosymbiotic hypothesis ==
Creation Ministries International writes:
‘In the endosymbiont theory, the ancestor of the eukaryotic cell (we will call this organism a protoeukaryote) is presumed to have been a large, anaerobic, heterotrophic prokaryote that obtained its energy by a glycolytic pathway. Unlike present-day bacteria, this organism had the ability to take up particulate matter … . '''The endosymbiont theory''' postulates that a condition arose in which a large, particularly complex, anaerobic prokaryote took up a small aerobic prokaryote into its cytoplasm and retained it in a permanent state [emphasis added].’
Whichever way it is stated, it is given an aura of authority and certainty by its frequent repetition in writings on cell biology. Many students find it convincing. However, like many evolutionary ideas, it may look solid from a distance, but gaps appear on close scrutiny.
The evidence for the endosymbiont theory revolves around selected similarities between mitochondria and bacteria, especially the DNA ring structure. However, these similarities do not prove evolutionary relationship. There is no clear pathway from any one kind of bacteria to mitochondria, although several types of bacteria share isolated points of similarity. Indeed, the scattered nature of these similarities has left plenty of room for a less-publicized ‘direct evolution’ theory of mitochondrial origin, in which they never had any free-living stage. There is enough diversity among the mitochondria of protozoa to make evolutionists wonder if endosymbiotic origin of mitochondria occurred more than once.
Mitochondrial DNA
The endosymbiont theory implies that there should be considerable autonomy for mitochondria. This is not the case. Mitochondria are far from self-sufficient even in their DNA, which is their most autonomous feature. Mitochondria actually have most of their proteins coded by nuclear genes, including their DNA synthesis enzymes.<ref>http://creation.com/mitochondria-created-to-energize-us</ref>}}
== History ==
== History ==