Isolating genes is usually done with simple PCR. These days you almost never isolate a gene without knowing it's sequence and then it's a matter of designing PCR primers that are unique (fairly straightforward). You can check that the appropriate gene is isolated by simple gel electrophoresis and once it's inserted into the vector (which makes amplification in an organism very easy) you can once again sequence.

Isolating the protein product after expression is a little bit more difficult but is well understood. Almost always you will use one or more liquid chromatography methods. You can append small "tag" sequences to the gene to create an amino-acid sequence that specifically binds to certain metals (HHH binds Nickel) or an antibody which can be immobilized on a solid "column". You can then flow a slurry of the bacteria that expressed the protein across the column and everything will flow past except your protein of interest. The protein can then be removed off the column with a different specific buffer. There are many variations depending on your protein of interest and application needs, but this is the general approach. In cases where tags can't be added due to activity needs or cost requirements, proteins can be isolated similarly based on their size, charge, and hydrophobicity. If you perform those separations in various orders and be clever about it, you can get very pure product.

Finally, confirming the final identity and activity of the enzyme might require mass spec and activity assays (if enzyme) where you can compare reaction rate of product vs. total amount of protein added to get an idea of the fraction of protein that is active.

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Thanks for explaining.

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Thanks for sharing the link.

I feel like this might be inaccurate as pigs are mammals and all mammal RBCs do not contain a nucleus when mature. Maybe it was a chicken as avian RBCs do contain a nucleus. Also, interesting fact camlids (camels, llamas, alpacas, etc) have oval red blood cells.

>what we mean is apart from all the visible light from the spectrum, red wavelength is reflected back to our eyes and rest all is absorbed

Actually, no. The perception of red is based on a weighted average of reflectivity at three different wavelengths. https://sciencedemonstrations.fas.harvard.edu/presentations/lands-retinex-theory-experiment#:~:text=What%20It%20Shows See also https://commons.trincoll.edu/wmace/courses/perception/lands-retinex-theory/#:~:text=The%20term%2C%20%E2%80%9Cretinex%E2%80%9D%20was%20coined%20by%20Land%20to,this%20by%20combining%20the%20word%20%E2%80%9Cretina%E2%80%9D%20with%20%E2%80%9Ccortex.%E2%80%9D

So your other question has to be rephrased a bit: what decides at the very root level, which wavelength_S_ to be absorbed _to what extent_ and which _oneS ARE_ is to be reflected _to what extent_. Very few things in the natural world reflect just one wavelength, nor even just one narrow range. For most things in the natural world, there's a mix of reflectances (and there can be other effects, as on butterfly wings).

We're now into the fourth decade of hundreds of millions of women taking the pill for 10-15 years (often with interruptions to have a baby) so if it had an effect on delaying menopause we'd already be seeing it.

>I believe menopause is triggered when a woman's body has no more eggs to release

There is nothing to "believe". It is proven science that says the ovarian follicles stops working at a certain age, no matter how many egg cells still are in there, which means lower blood hormone levels as the follicles during the fertile period produce estrogens, androgens and progestins.

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Yes. Porcine endogenous retroviruses (PERVs) can infect human cells in cell culture.

https://www.nature.com/articles/nm0397-282

A biotech company made a gene-edited pig a few years ago with all of the PERVs knocked out. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5813284/

The goal is to have a safer source of organs for xeno-transplantation. Giving a pig organ with PERVs to an immuno-suppressed patient is a bad idea.

Solar disinfection is used effectively in remote communities in the developing world. The effect is amplified by leaving the bottles on reflective surfaces. It's not great and it takes hours but it is effective.

See here for an academic source: https://link.springer.com/referenceworkentry/10.1007/978-3-319-70061-8_125-1#:~:text=Solar%20disinfection%2C%20or%20SODIS%2C%20refers,at%20least%206%E2%80%938%20h.

Wiki: https://en.m.wikipedia.org/wiki/Solar_water_disinfection

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Because it takes time, and additional fresh bacteria and whatnot can land on the exposed surface all the time.

I suspect that even 1/8th of an inch under the surface there would be a much higher bacterial and viral load because of the moisture and being shielded from the sun.

A bit of sidewalk under, say, a quartz glass dome would probably be pretty much sterilized after a few days in the sun, from UV and heat.

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The shortest answer to your question is: physics and chemistry!

Ok so just a couple quick things: you are correct that the color we perceive is based on the spectrum of light which reaches our eyes. But there are a lot of other factors beyond the pure absorption of the object. For example, the spectrum of the source (eg a lightbulb has a different “color” of light than the sun) as well as the intervening medium (air interacts with light differently than glass, and dusty air is different than pure air). And there are ways for light to interact with an material beyond absorption (like scattering). But generally speaking you’re on the right track.

So, light comes in discrete packets called photons which have an energy. Because of quantum mechanics that energy is directly linked to the wavelength. In other words, different wavelengths of light have different energies. When light hits an object, light is so tiny that what we’re really talking about is light hitting the molecules which make up that object. Now, again due to quantum mechanics, each molecule (and each part of the molecule) can only have different set energy states. Making up numbers but let’s say it can be 1, 2, or 2.5. But it can’t be say, 1.7 or 2.8. So going back to the light, let’s say the molecule is generally in state 1, which physicists call the ground state. If the photon has an energy of 0.7 it can’t interact* with the molecule, but if it’s 1 it can boost the molecule up to 2 and if it’s 1.5 it can boost the molecule to 2.5. Now, remember that each energy of photon is tied to a wavelength? This is the mechanism by which some wavelengths get absorbed but others do not. For a given material this is expressed as an absorption spectrum, which is a graph that shows how strongly different wavelengths of light are absorbed. Add together a weighted average of the absorption spectra for all the materials in the skin of an apple, and you get the overall absorption spectra which determines what color the apple’s skin is. In the case of a red apple, shorter (bluer) wavelengths are more strongly absorbed than longer (redder) wavelengths.

As to where that extra energy goes, the molecule will eventually return to its ground state. In most situations for light in the visible spectrum, the energy ends up lost to heat (at a molecular level, the molecule wiggles a bit faster). In other words if you shine a light on a thing, it’ll get hot over time and that heat is the energy coming from absorbed photons.

Now, I’m glossing over a whole lot here, and the reality is more complicated than I’m describing in a lot of important ways. For example most molecules have tons and tons of different energy states, eg vibrational, rotational, electron energy levels, chemical bonds, etc. And in practice there’s usually a narrow range of acceptable energies that mean you don’t get a perfectly sharp peak. But hopefully this is enough to get you started.

Gonna need a citation for being able to sterilize water by leaving it in a bottle in the sun.

Here's a paper on habitability around brown dwarf stars:

https://iopscience.iop.org/article/10.3847/1538-4357/ab5b13

It does say that brown dwarfs cool much faster than our sun, so I think your story's premise is plausible. The paper assumes you need at least 1 billion years for life to evolve so the mass of the star must be at least 20 Jupiter masses or it'll cool too fast to remain in the habitable zone. It further limits the minimum mass based on requirements for photosynthesis and UV output.

No. Eggs still "die", even when they aren't released for fertilization. They're just absorbed by the body instead of being excreted by it (along with the linings that would have been used to support said egg). Best you could possibly hope for (re: delays) is a month or three (and that's hardly significant by then)

It's about intensity and time. UV radiation used for disinfection is very high intensity and short duration. Thus makes it useful for disinfecting at scale. UV from sunlight is, however, low(er) intensity, long duration, so, while it can disinfect, its not good for doing so at scale. You'd probably be surprised at just how "clean" a sidewalk is, in all honesty: if not exposed to the sun's rays, it'd be a lot less "clean", which is not to say that its clean at all, just that it would be a lot worse without the sun

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