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13

When our skin is exposed to the sun, this can cause some damage in the upper layers of skin. This activates DNA damage repair and also induces signalling towards the melanocytes (which produce the pigment). Signalling means the excretion of signalling molecules (mostly alpha-Melanocyte stimulating hormone, aMSH) which binds to the MC1R receptor (melanocortin ...


8

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 ...


5

First, one should mention types of skin: skin type defines how the person will tan - Second, the solar radiation (UV) absorbed by sun defines the amount of melanin produced by melanocytes of the skin to protect the skin = melanogenesis (which in turn depends on skin type). When the solar exposure diminish, the natural repair processes causes ...


5

Some additional details on the same lines as Chris' answer: Coelho et al. have studied the short and long term effects of UV on human skin and they report that there are different stages of tanning: Immediate pigment darkening: happens in a few minutes and persists for some hours. It is most probably due to melanosome redistribution and melanin oxidation ...


4

Qiagen and Life Technologies call it RNA content, total RNA, or total cellular RNA.


4

It is just a way of highlighting your search term. If you search M00115+C03722, you will see C03722 in red.


3

I'm not entirely sure about cross species organelle transfer (lets focus on mitochondria), but some people have already made three parent babies, therefore mitochondria are at least transferable between individuals of the same species. The reason for the operation was to cure a disease that was inherent to the mitochondria of the mother (mitochondria ...


3

There are two things happening: First melanin absorbs the energy from the UV radiation and releases it as infrared energy and thus protects the cells in the skin. This happens in all people, the deeper the skin color is, the better is the protection. What is different between people is the amount of pigment they produce, the number of melanocytes is ...


3

Zabner et al (J. Biol. Chem., 1995, 270, 18997-19007) monitored the lipid-DNA complex formation and uptake which was found to be predominantly by endocytosis. Dot blot experiment shows that cells (50% population) took up 60% of the DNA. The DNA-protein complex was observed to be deposited in the perinuclear cytoplasm and formed a series of regularly packed ...


2

All biomolecules are eventually broken down. This process is called turnover. Since inositol is a signalling molecule it is necessary to remove in order to terminate the signal, despite adaptive mechanism in the ER calcium channels. IP3 is generally dephosphorylated by a family of phosphatase enzymes called inositol polyphosphate phosphatases. After ...


2

In early embryogenesis, cell division called cleavage occurs every 30 min and there is no transcriptional activity. Oocytes have accumulated important gene transcripts and synthesize the proteins at right times. However, histone is one of the most abundant proteins and it would be difficult to supply enough histone proteins during early embryogenesis while ...


2

To build on busukxuan's answer, there are a lot of single-celled organism responses that kind of resemble memory: Slime mold uses an externalized spatial 'memory' to navigate in complex environments - essentially, a slime mold leaves behind a trail, which it then avoids, allowing it to avoid where it has traveled in the past. If you apply a periodic ...


2

That module represents Entner-Duodoroff pathway, which is an alternative pathway to the Embden-Mayerhof-Parnas pathway of glycolysis. Entner-Duordoff pathway exists only in prokaryotes.


1

High and low are not very descriptive since they are relative. ATP hydrolysis may have a high activation energy compared to some reactions and low when compared to others. The important point is that the activation energy is sufficiently high enough such that ATP is not rapidly hydrolysed under physiological conditions before it can do useful work. In other ...


1

The idea to compare biologic cells and crystal is mostly related to a German physiologist Theodor Schwann (1810-1882): His work "Microscopic researches on the Conformity in Structure and Growth Between Animals and Plants, 1839 relates to this idea. He believed that new cells form principally outside pre-existing cells, and wanted to draw an analogy ...



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