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12

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

The reason why the cell would shrink more in CaCl2 solution is because it has a higher van't Hoff factor i.e. total number of dissociated ionic species per solute molecule (it is 2 for NaCl whereas it is 3 for CaCl2). (Nonionic solutes do not dissociate and will therefore have a van't Hoff factor of 1) Osmotic pressure (and other colligative properties) ...


6

A perfectly reasonable definition of a ligand from Wikipedia: In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. A ligand can be anything, so long as it binds to a biomolecule. Often, the ligand is a small molecule or peptide, and the thing that it binds to is a protein. On ...


5

In biology ligand is a very broad term. Everything is called a ligand that has a receptor for it, regardless whether it is free or membrane-bound. There is very much sense in membrane bound ligands, because many cells in our body are capable of actively moving around (for example T-cells). Cells can use signal transduction by direct cell-to-cell contact - ...


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

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 ...


4

Although transmissible cancer has been found in some species, such as Tasmanian Devils and clams, it is quite rare in most species. Certain viral and bacterial agents that cause cancer, however, can be transmitted. One example is HPV, which can cause cervical cancer


4

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.


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 ...


2

It's commonly believed that it's muscle cells that have the largest amount of mitochondria, and for good reason. Muscle cells are continually used to move the body, so they have the most mitochondria because of the large energy requirement. If you want to be more specific, the muscle cells of a marathon runner have even more since the muscle cells involved ...


2

It would be stressful for cells to be trypsinized 24 hours after seeding. After cells are plated, there is a lag time to start growing. Perhaps, during the lag time, physiological state of cells is stabilized. They have to express proteins digested by trypsin and display on the surface etc. Then you could disturb the state again by trypsinizing cells again ...


1

Might be considered "not answering the question" but: Option 1: Depending on the type of cells you are using, you can use milder methods to detach cells. Example include Versene which is essentially PBS + EDTA. Milder still is to just use PBS that has no Mg or Ca (no chelation). Option 2: Duplicate your setup - instead of two dishes - one with drug, one ...


1

It is not advisable to trypsinize the cells too often when you have to maintain them. However, in your case the situation is different. Time required to attach depends on cell type. In any case while performing an experiment, your cells should not be already under stress. Therefore you should seed the flasks/culture plates with a smaller concentration of ...


1

There is a reasonable speculation. That is to get more areas where ATP synthases are localized in order to produce ATP. But this doesn't tell why the structure has to be the exactly that shape. As the review Ilan show, the shape seems to be determined by ATP synthase dimerizetion. The shap may be just a consequence of ATP synthase dimerizetion, although ...



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