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34

SolarLunix posted an excellent answer detailing the criteria for being classified as "alive", and showed that by those criteria, mitochondria could be considered as "dead". However, I would argue that the narrator's statement in your video does not make any sense. The currently-accepted theory of the evolution of mitochondria (and possibly other organelles) ...


17

I think @mbq has covered the frequency question better than I can. There is at least one modern example of this kind of new organelle formation. Aphids have a deep, intracellular endosymbiont Buchnera involving some genome transfer that has developed in the last 200 million years. There are many articles about this topic (eg: Nature from 2000), and it ...


15

According to "Resolution of distinct rotational substeps by submillisecond kinetic analysis of F1-ATPase" (Yasuda et al., Nature, 2001), ATPase rotates at 130 revolutions per second when saturated with ATP.


15

Well, it seems quite obvious that it was not a single I-eat-you-but-you-survived act but rather a convergence of endosymbiotic and host species into a greater and greater cooperation. Of course this leaves a question if there was one or more species of endosymbionts involved. Mitochondria are a very primeval story forced by the oxygen catastrophe, so it is ...


13

Mitochondria evolved before chloroplasts. We know this because Mitochondria form a monophyletic group: e.g. all life with mitochondria traces back to a single common ancestor (source). Since the group with chloroplasts groups within this clade, it must be the case that either (a) chloroplasts were obtained by an organism that already had mitochondria or (b) ...


13

Short answer: According to the definition of life, yes, Mitochondria are "dead". To be considered alive an organism must meet the following criteria: organized structure performing a specific function an ability to sustain existence, e.g. by nourishment an ability to respond to stimuli or to its environment capable of adapting an ...


12

This is one of the most intriguing questions of eukaryotic evolution. As far as I know and have read, the autogenous theory is not accepted. There are quite some reviews on this topic. Also there is a wonderful book by Nick Lane on mitochondria called Power Sex and Suicide. You would be interested to read it. There are no sufficient evidences for the ...


11

Mitochondria are comprised of ~3000 proteins. However, the mitochondrial genome has only 13-14 protein-encoding genes. The remaining 99.6% of mitochondrial proteins are encoded by genes in the nuclear genome. (Wikipedia) Chloroplast genomes are only slightly larger (~100 genes). Gene regulation and signaling between the nucleus and mitochondria (and between ...


11

...would then be his offspring at risk? Why? No. Generally speaking, fathers do not pass on their mtDNA (Mitochondrial DNA). Why? Because the mitochondria present in oocytes (egg cell) is the mother's, as every oocyte directly inherits the mother's mitochondria when they are made in the reproductive organs. The mitochondria that the sperm from the ...


11

I would like to expand a bit on SolarLunix's post, because the logic used in the conclusion would also mean that endosymbionts, such as https://en.wikipedia.org/wiki/Buchnera_(bacterium), who cannot survive outside their host are also "dead". I think many of us disagree with that notion, so instead I would say that it's the fact that so many of their genes ...


9

There is evidence that cells can exchange mitochondria. There are some donor cells that transfer mitochondria to recipient cells via cytoplasmic nanotubes (within the same species). This happens endogenously and triggering factors may include stress. References: Pasquier et al. 2013 Ahmad et al. 2014 Wang and Gerdes. 2015 On interspecies mitochondria ...


7

Maternal inheritance of mitochondrial DNA is very well conserved, although some species, such as some mussels, show paternal inheritance. As for why or what the advantage is, some of it is due to basic logistics: sperm cells have ~100-1000 mitochondria, egg cells have 105-106, so male contributions are largely washed out. Plus, most mitochondria in sperm ...


7

I would say it has to do with the amount of mitochondrial or sequence that has been transferred to the host genome. As a consequence of all this information stored in the host genome, mitochondria cannot reproduce without the host. In this way, they are not their own organisms, but rather organelles. Over evolutionary time, the line between organelle and ...


7

There are metabolic processes in which ATP is synthesised without the involvement of ATP synthase. The best examples are, in fact, two steps in the glycolytic pathway, catalysed by phosphoglycerate kinase and pyruvate kinase. This is why, in the absence of any aerobic metabolism, many organisms (like yeast for example) can grow quite happily, producing two ...


7

I do not have a definitive answer but I can argue that mitochondria came into existence before chloroplasts despite the fact that, between their free living ancestors- $\alpha$-proteobacterium and Cyanobacteria, the latter seems to be older in evolution. I have following points to support this argument: The organisms that have chloroplasts also have ...


6

The textbook version for the regulation of ATP involves a feedback loop with phosphofructokinase (PFK). The relative concentrations of ADP and ATP are characteristic of the energy state of the cell. If the cell is using energy, then there will be an excess of ADP. If not, then ATP. ATP is an inhibitor of PFK, which in turn slows glycolysis (thus reducing ...


6

It depends of what you call endosymbiosis. In the sense of mutualistic interaction between host cell and intracellular organism, it also include Rhizobium bacteria and Fabaceae plants, some Cnidaria and algea in their cells, and even some micorrhizal fungi that invade into plants cells. But parasitic interactions are also sometimes call symbiosis, as ...


6

According to my knowledge, this was the molecular and cellular evolutionary path of life. Synthesis of essential building blocks (fatty acids, aminoacids, cofactors...) Condensation of building blocks First RNA replicase; RNA genomes (differentiation between genomic and functional RNA, primitive metabolism) Ribosomes and first matrix dependent ...


5

We know about nuclear DNA having a mitochondrial origin mainly in two ways: (1) a sequence in the nucleus is found to closely match a sequence found in mitochondria, or (2) mitochondrial proteins are found to be encoded by the nuclear genome but not by the mitochondrial genome, and those proteins seem likely to have been necessary for sustaining life of the ...


5

Interesting question. I researched this a bit now and the phenomenon is termed "numt" for "nuclear mitochondrial DNA". This term descrives the transfer of cytoplasmic mitochondrial DNA sequences into the separate nuclear genome of a eukaryotic organism. It seems that most of these sequences are inactive. This list at pseudogene.net has a large number of ...


5

What is difference between plastid, chloroplast and mitochondira? Plastid is a general term for an organelle which consists of Chloroplasts, Chromoplasts, Leukoplasts/Amyloplasts and Apicoplasts. Chloroplasts (Chloro = green) are involved in photosynthesis; they express Chlorophylls and have the thylakoid structures which are involved in the electron ...


5

The passage of protons through the FO (membrane) portion of the molecule (driven by the electrochemical gradient of protons across the respiratory membrane) generates torque at the interface between the a and c subunits. This mean that the ring of 10 c subunits rotates relative to the a subunit. The γ subunit in the stalk rotates along with the ring ...


5

In general, $NADH$ and $FADH_2$ are coenzymes. The structure of the main part of an enzyme determines which coenzyme or which prosthetic group will work with the concerned enzyme. Unlike most other TCA cycle enzymes, Succinic Dehydrogenase involves the participation of $FAD$ rather than $NAD$ and that is a consequence of its specific structure. Another ...


5

TL;DR: Ubiquitin. Occasional occurrence of paternal inheritance of mtDNA has been suggested in mammals including humans. Clearly, spermatozoa have mitochondria; they make the energy needed for motility. Paternal mitochondrial DNA (mtDNA) does enter oocytes. It is a persisting fallacy that only maternal mtDNA is present in humans because only oocyte ...


5

A simple method would me to express a fluorescent protein in the cell that specifically localizes to mitochondria. mito-dsRed is a Red Fluorescent Protein which has that property; it can be expressed from a plasmid. Using fluorescent microscopy and image analysis, you would be able to measure the geometric properties of the mitochondria. This can be done at ...


4

This link seems to have good information that answers most of your questions. In my mind, there are two types of mitochondria: ones that work and ones that don't. Mitochondria do have DNA but that mDNA is there to encode proteins for their specific functions (e.g. to create ATP). So, although the mDNA may not be uniform for every mitochondrion in your body, ...


4

For starters, see this thread. My understanding is that the ancient predecessors of mitochondria were free-living unicellular organisms. Supposedly at one point, these mitochondria-like cells developed an endosymbiotic relationship with a larger cell. This relationship was advantageous for both cells: the smaller cell could focus on energy production, ...


4

It's hard to understand the question, but in any immunocytochemical staining such as the above, you have two different types of reactions: the antibody binding to the target (in this case, some laminin) the peroxidase-based colorimetric reaction with DAB. DAB (3,3'-diaminobenzidine tetrahydrochloride) is oxidized in the presence of hydrogen peroxide to ...


4

ALiceD's comment is perfectly true. (Though in real cases, the short circuiting is seldom absolute as there is usually some finite resistance in the short circuiting wire.) You can understand this in two ways. Intuitively, the uncoupling provides a channel for the hydrogen ions to move across the membrane in the direction of their electrochemical gradient ...


4

No there aren't any organisms with fully functional mitochondria which (the latter) do not retain the minigenome. On whether it is theoretically possible to transfer all the mitochondrial genes to the nucleus: Perhaps it is possible and mitochondria may work just like lysosomes and ER, but I think that the responses will be greatly delayed. At present ...



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