Skip to content

{ Category Archives } various

What is the scenario for the endosymbiotic theory?

The endosymbiotic theory seems easy to understand, a bacterium engulfed by another cell. Apart from the problems in identifying the host, there is ambiguity whether the invader was single- or double-membraned but they distinguish between two different scenarios.  
The first is a eukaryotic cell that engulfed a bacterium by invagination of the membrane (here), thereby providing the […]

Antibiotics, bacteria and mitochondria

Antibiotics are used in medicine by their discriminization between bacterial and eukaryotis cells (e.g. human) meaning that a bacterial infection in humans can be treated without affecting the normal body cells. If mitochondria would be derived from bacteria, we would expect an effect of antibiotics on eukaryotic cells where mitochondria are essential for metabolism. So, that would […]

Bacterial cell membranes

Bacterial membranes and mitochondrial membranes are quite different. Bacterial membranes consists of a lot of specific proteins with specific bacterial functions giving protection and rigidity to the cell. I think anyone would agree that the mitochondrial membrane has few characteristics in common with the bacterial membrane, as you can see from the wiki entry. Observe […]

Morphological descriptions of mitochondria

Next to the various images that suggest a reticular mitochondrial morphology, mitochondria are also described as highly dynamic, reticular structures.
Mitochondria occur in various forms depending on the cell or tissue type and even within single cells, reflecting the variety of cellular functions localized to these organelles (Yaffe 1999, Collins et al. 2002). In S. cerevisiae, mitochondria can […]

Endosymbiotic bacteria in eukaryotic cells

These images show endosymbiotic bacteria with an emphasis on Rickettsia, which is always mentioned as the alpha-proteobacterial organism that is closest related to mitochondria. This was proposed because these are bacteria that are living inside eukaryotic cells. As I find that mitochondria do not look like bacteria, but more like a eukarytic endomembrane, I am also […]

Pictures of the Tree of Life

In this place I keep different images of the Trees of Life, I am trying to get a diverse collection of Trees. On of the problems with the Trees is that we can identify the end points, being either extant or extinct known organisms, but that it is more difficult to determine what the organisms at a junction would look […]

Mechanistics explained in literature II: Textual explanations

Since I see unsurmountable problems in a mechanistic scenario for the origin of mitochondria, I am interested how the proponents of the endosymbiotic theory explain the mechanistic steps leading from a bacterial symbiont to the organelle we see now. Everytime I encounter an explanation, I will put it here, but so far, I haven’t been able to find […]

Mechanistics of the endosymbiotic theory I: Figures

In this post I collect images that show a mechanistic scenario for the inclusion of a free-living bacterium into another cell. It is not known what the host looked like, whether it was a primitive eukaryotic cell or another prokaryote. Consensus is the latter, although it doesn’t make a real difference for the scenenario. My […]

Illustrations of mitochondria

This post shows the normal way mitochondria are depicted in textbooks and across the web. It sure contrasts with the real images of mitochondria that often show a that they form a network (reticulum) in the cell. Probably the illustrations are made with the endosymbiotic theory in mind where the mitochondrion has to look like a bacterium. […]

Images of mitochondria

I collect images of mitochondria and would like to share them with the rest of the world. As you can see for yourself, it is an enormous variety and there is nothing that even remotely looks like a bacterium in these pictures. The classical picture of the circular mitochondrion is in reality often just a […]