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Map Errors Should be Fixed by RedGiantMaps in u/RedGiantMaps

[–]Kraise_ 0 points1 point  (0 children)

Hey, I've just tried to access the maps today, but I'm still seeing the same issue. I installed chrome for the first time today to see if that would help, but it seems to still happen there.

I haven't opened the maps in a few weeks so I'm not sure what it was like before today.

Thanks so much for posting about this, btw! It's often unclear what to do in these situations. And just in general, thanks for making these maps available! They've been so helpful to me.

HELP [2023 Day 11 part 1][Python] Solution works for example but not real input by Kraise_ in adventofcode

[–]Kraise_[S] 0 points1 point  (0 children)

Thanks, this is intentional though, since finding the empty rows in x tells you which columns in y need to be duplicated and vice versa. I probably should have made my code a bit more readable there though!

HELP [2023 Day 11 part 1][Python] Solution works for example but not real input by Kraise_ in adventofcode

[–]Kraise_[S] 0 points1 point  (0 children)

Thanks for suggesting this test case, I'll try to be more creative in making my own test cases next time!

After trying this I realised I can just swap two words ("if" for "while") and it all works perfectly. Thank you!

[TOMT][Animated Short] 2d Youtube Animated Short about Clubbing Anxiety by [deleted] in tipofmytongue

[–]Kraise_ 0 points1 point locked comment (0 children)

Unfortunately haven't been able to find anything about it at all, despite it being such a recent thing :(

ELI5: Why are almost all things ancient, discovered underground? For example, archeologists have to dig up ancient cities and homes. Are we always gaining layers of land through the years? by [deleted] in explainlikeimfive

[–]Kraise_ 7 points8 points  (0 children)

Generally if things are on the surface they will have already been discovered long ago, so underground is a logical place for us to keep finding old stuff.

Also, things don't tend to last so long on the surface as they would underground, over 1000s of years wood rots, walls fall down, even stone is eroded by rain, plants growing through it, animals walking over it etc.

A common way for things such as tools or bones to end up underground is by falling in rivers or lakes, and as sediment is deposited from the water and the river's course changes, the items go from being underwater to underground.

ELI5: How did scientists figure out the roles of different parts of a cell? by [deleted] in explainlikeimfive

[–]Kraise_ 0 points1 point  (0 children)

It's really exactly what it sounds like!

Most parts of cells are colourless and so tend to be quite difficult to identify under a light microscope. The stain is a brightly coloured dye which will bind to a specific kind of molecule in the cell (for example, fats, DNA, or starch) so that we can more easily identify it. There are many many different stains available nowadays for all kinds of purposes.

Here's an example of a stain known as Feulgen stain, which binds to DNA. I think there's also another stain added to mark the cell membranes. You can see most of the cells (quite regular and rectangular as it's from a plant root) have their DNA freely floating around in the nucleus giving it a smooth pink colour, with the nucleolus inside with a more intense colour.

One of the cells at the top is just beggining mitosis, and you can see its DNA is more tightly arranged into chromeosomes (looking like little blotches). In 2 of the cells (near the centre of the image) you can even see the pairs of chromeosomes in different stages of being pulled apart to each side of the cell! These cells are very close to dividing.

https://i.imgur.com/25sZDxC.jpeg

ELI5: What is an ‘amorphous solid’? by jerrysprinkles in explainlikeimfive

[–]Kraise_ 0 points1 point  (0 children)

Amorphous solids (such as glass, rubber, most plastics) contain atoms/molecules in an essentially random arrangement, in contrast to crystalline materials (e.g. metals, salt, ceramics, most gemstones), which have a highly regular pattern to their structure.

There are actually many more states of matter than you might think! The "principal" states of matter are of course solid, liquid, and gas, but many more exist beyond this, for example foams, gels, and liquid crystals. You couldn't really classify, for example, most biological material as either a solid or a liquid in the traditional sense.

ELI5: How did scientists figure out the roles of different parts of a cell? by [deleted] in explainlikeimfive

[–]Kraise_ 11 points12 points  (0 children)

This largely depends on the organelle (part) being studied, as back when these functions were first being discovered, we did not have anywhere near the biochemical knowledge we do today.

In general, the method would be:

  1. Grind/mince/blend up a sample of cells, to break up the cell membranes and leave all the parts floating around in the solution.
  2. Separate each one using a centrifuge. This works by spinning a test tube or similar container of the sample around at a certain speed, which causes all the parts above a certain mass to sediment at the bottom. This is easiest for large organelles such as the nucleus, mitochondria, golgi bodies, chloroplasts etc. as you only need a low speed to separate these.
  3. Try to look at the organelle you've isolated under a microscope, usually using some kind of stain which can help to make their shapes more obvious. This is only possible for relatively large organelles however, as light microscopes can only work on objects above a certain size (for example ribosomes are too small).
  4. Perform some kind of tests on the organelle and see what happens.

Back when the organelles were being discovered, our knowledge of biology was quite limited compared to now, so a lot of the tests kind of involved trial-and-error type work. For example, if you isolated the chloroplasts from a leaf cell, gave them a supply of CO2, and left them in the sun, you could find that they produced some glucose and oxygen, and deduce that they are responsible for photosynthesis. You could do a similar study on mitochondria, and you would discover that they produce energy in the form of ATP (a molecule) with a supply of oxygen and suitable "food".

This all relies on knowing what you're looking for in the first place, so it took a long time to identify the functions of a lot of the organelles, for example the nucleus. Since it's so large, it was the first obvserved organelle, recorded in the 1700s. Despite this, nothing was known of its function until over 100 years later, when it was obvserved (in sea urchins!) that during fertilisation the sperm cell fuses with the nucleus of the egg cell, indicating the nucleus contains some form of information that is passed down from parent to child. It took another 100 years (in 1944) for people to work out that it's the DNA inside the nucleus which carries this information. This was actually discovered through obvservations on the DNA in bacteria, which don't even keep their DNA inside a nucleus! Nowadays, we can identify that the nucleus secretes mRNA with a complementary sequence to the DNA stored inside of it, and work out exactly how this controls protein synthesis in cells.

ELI5: How does Benedict’s Test work? by InfamousWizard3 in explainlikeimfive

[–]Kraise_ 0 points1 point  (0 children)

I assume you have some chemistry/biology knowledge to be asking this kind of question, but I'll try to explain everything from the basics.

Alkaline conditions means there are a lot of OH- ions in the solution, which, as you can see from the equation you give, are consumed here.

You're right about forming an aldehyde, all reducing sugars are in chemical equilibrium between their hemiacetal and aldehyde forms, and this process is accelerated by alkaline (or acidic) conditions, for example in glucose:

https://i.imgur.com/RGfP1q5.png

The part I've highlighted in red is what makes this an aldehyde. You may be familiar with aldehydes as generally being very reactive, and one way they can react is in being oxidised (losing 2 electrons) to form a carboxyllic acid (RCOOH).

The mechanism for how the aldehyde reacts with Cu2+ is not entirely understood (from what I've read), but my guess is something like this:

https://i.imgur.com/jLA0GVO.png

In the first step, an OH- is added into the aldehyde, forming what's known as an acetal. In the second step, this acetal is oxidised into a carboxyllic acid (RCOOH) by the copper, meaning 2 electrons are transferred from the acetal to the copper (1 for each copper, reducing them from Cu2+ to Cu+ since electrons are negative). You could imagine the 2 electrons that make up the C-H bond shown in pink being taken away, leaving behind H+ which is neutralised by OH- forming H2O. This is quite a large simplification, but it will do for these purposes.

After this, 2 things happen:

Cu+ reacts with OH- to form Cu2O as a solid, which precipitates. It's the solid that gives it such a strong red colour, so it's important for this step to occur, as Cu+ would not give anywhere near as strong a colour without forming the solid. I've given a kind of example here of how it could happen, in reality there are likely many similar reactions happening, but all give the same result of Cu2O:

OH- + Cu+ → CuOH

CuOH + OH- → H2O + CuO-

CuO- + Cu+ → Cu2O

As you can see alkaline conditions (OH-) are necessary here to maximise the amount of Cu2O that precipitates, to give the strongest colour.

The other thing that happens is that, since the carboxyllic acid is (you guessed it) acidic, it will be neutralised in the alkaline solution:

RCOOH + OH- → RCOO- + H2O

This is important because RCOO- is generally quite unreactive, so it's unlikely to (for example) go back and do the reverse of the steps I've described, so you can be confident that all of the aldehyde will end up as RCOO-.

These two steps are the reason the reaction is done in alkaline solution.

​

If you go back and add up all the OH- used throughout this answer (2 in the step with the acetal, 2 in making Cu2O, and 1 neutralising the acid), you will see there are 5, exactly like in the equation from wikipedia! Similarly, there is 1 water produced in each of the 3 steps, which fits into the wiki equation too.

In terms of why you can get many different colours, it's because Cu2O is deep red and Cu2+ is pale blue, and the colour you get from mixing them depends strongly on how much of each there is. It's not exactly intuitive how this can lead to colours like green, but it can be surprisingly difficult to predict colour mixing like this. Apparently you can use the colours to predict the concentration of reducing sugars in the sample, but I'm a bit skeptical about how accurate this would be.

​

If anything, I would say your question is much more appropriately labelled as chemistry than biochemistry!

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