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Isn't there a possibility that cell division will result in a daughter cell with no mitochondria? Yes, there is always the possibility. However, there must be a strong negative selection pressure against eukaryotic life that cannot achieve the proper partitioning of mitochondria, so you can imagine that there are mechanisms in place to prevent this case. ...


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In addition to S Pr's excellent example, I wanted to point out that some very recent research describes some special behavior in oocyte development specifically related to mitochondria selection. Here's a easy-to-read version: https://www.sciencedaily.com/releases/2019/05/190515131741.htm Here's the original version in Nature: https://www.nature.com/...


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A typical animal cell has 1000-2000 mitochondria. From a statistical point of view, assuming a random distribution of the mitochondria and that the cell splits in half, the probability of having 0 mitochondria is (1/2)^1000 or 9e-302. This makes it an impossibility for all practical purposes. With enough mitochondria, a process to ensure the cell splits ...


7

Yes it can, because exposure alone can cause mutations in your genes which is usually the main cause of cancer. For example, when we get exposed to UV light for longer periods of time, we can get skin cancer/melanoma. Here , of course no traces of these rays are present in our body, its just all due to prolonged exposure. Now to the fact that why does it ...


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Epigenetic marks are reversible (you might be aware of induced pluripotent cells). Many animals can regenerate organs with high tissue complexity (such as a limb) and this involves de-differentiation in some species (Sandoval-Guzman et al., 2014). Even otherwise, cells can respond to extracellular/environmental cues to modify their epigenetic state (for e.g. ...


3

Context is important. A/T == 1 and G/C == 1 (approximately, to within a measurement error) are Chargaff's rules for double-stranded DNA, occurring because A pairs with T and G pairs with C. (A+T)/(G+C), or (G+C)/(A+T+G+C), are completely different ratios unrelated to Chargaff's rules. These are roughly constant across individuals for a given species and ...


2

Apparently, olfactory axons and GnRH producing neurons are among the first neurons that migrate from neural crest at around 39th day of gestation in humans (Cassoni et al., 2016). In rodents, early GnRH neurons migrate together with a heterogeneous coalescence of placode-derived and neural crest-derived migratory cells (Forni et al., 2011) and ...


1

A substrate is an underlying substance or layer, or less strictly, the medium within or upon which an organism grows. For instance, you can have a filamentous fungus grow on a solid medium (e.g. on an agar plate) or in liquid medium (e.g. in a shaken flask containing a solution) and its substrate would be the contents of the agar or solution. It's nothing ...


1

If you are asking if histone mass represents a larger percentage of total chromosome mass then the answer is yes when considered at the level of the nucleosome. Each histone-octamer wraps ~147 base pairs of dna around 1.7 turns. The histone-octamer consists of two copies of each of the four structural core proteins (H2A, H2B, H3 and H4). The sequence ...


1

The ENCODE consortium classifies human and mouse genome elements to try to answer this very question. Work by ENCODE suggested up to 80% of the genome is functional in some way. In other words, by that upper-bound measurement, there is apparently more to DNA's role in biology than just encoding genes — there's a lot going on under the hood. Case for ...


1

I don't think there is a single "class of graph" that isn't used in biology. In biology (just like in any other natural science), we have all kind of data types; non-ordinal variables boolean ordinal categorical numeric tree data other types of network data pure functions (from statistical or theoretical models) pictures sounds etc.. We make all kind of ...


1

The center of the cell in this case is a way to say "the nutrients arrive to every part of the cell", and should not really be taken literally as "the center". If the cell is modeled as a sphere, with the nutrients diffusing in from the outside, the whole sphere would be filled with nutrients when the nutrients "arrive to the center". Figure 1 shows how the ...


1

Please notice that cancer cells do not grow or divide faster than normal cells, although many people believe that, and most forms of chemotherapy were designed on the assumption that they grow faster. Actually, what makes cells cancerous is the lack of control of cell growth, so that they keep on growing without limit, even if slowly. On the other ...


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