is beehaw related to lemmy?

  • 1 Post
  • 24 Comments
Joined 1 year ago
cake
Cake day: June 8th, 2023

help-circle
  • Like you said, there’s a metric ton of steps involved in the overall process, and our understanding of each of these ‘levels’ of organization varies quite a bit. Closest to my personal expertise is the sub-cellular and cellular level, for which I would refer you books or papers in developmental biology, developmental genetics, and epigenetics. I can give you a couple bloopers to get you excited though:

    When it comes to deciding where different organs will form (again, from a sub-cellular level), it essentially starts from a concentration gradient of certain proteins/chemicals inside the zygotic cell. This gradient then determines the level of activation of other proteins, each level then leading to different biochemical cascades which, once more cells have formed from the zygote, determine which organ systems will come from them. Messing around with this concentration gradient can, thus, dramatically affect an organism’s development, leading to, for example, a body with just ‘left’ organs on both halves, just ‘top’ organs on both halves, missing an entire organ system (like circulatory system and heart) and so on.

    A more or less similar process occurs to determine the shape of organs. As a simple example, when some animals with regenerative capabilities (like axolotls) lose a limb, they are able to regrow the limb to the exact same length as before. Turns out, each cell on the periphery of their limb has a certain concentration of receptor proteins on its surface, which acts as a molecular ‘signature’ of that cell’s position in the limb. These signatures provide information on how far to grow the limb for regeneration, and some chemicals, lile retinol, can even override these signatures and fool the organism’s body into regrowing the limb from scratch on top of the place of regeneration.

    I hope these examples give you an introduction to the mechanisms involved. There’s obviously a lot more involved, so I would again highly recommend textbooks and research papers if you’re interested.





  • Paint it as a chemical reaction in order to understand its equilibrium state. We basically have:

    H2O (gas) ⇌ H2O (liquid)

    By sealing the jar with the water already boiling, we initialize the system to be in a state with equal(ish) amount of both liquid and gas. Then we allow the system to cool down so that the liquid water is no longer boiling. Now the system sits at an equilibrium between liquid and gas states.

    Now, when we put ice on top of the jar, the water vapor condenses and gets converted to liquid, pushing the equilibrium to the right. But this decreases the overall pressure in the system since fewer particles now occupy the volume above the liquid’s surface. This is essentially the system trying to pull itself back towards the original equilibrium i.e. towards the left of the equation, which it does by making more water vapor i.e. boiling.

    This reaction-like picture helps in visualizing the system better in some cases, so I tried to add it alongside the pressure dynamics scenario. You may be interested in Le Chatelier’s principle if you prefer this.


  • When the water vapor inside the jar comes in thermal contact with the ice outside, it condenses and precipitates. This decreases the vapor pressure inside the jar, which then causes the water to boil.

    Boiling is not just a temperature-based phenomenon, it’s also a pressure-based one: a water body maintains an equilibrium between liquid water and water vapor right above its surface. If you remove the water vapor from above the surface, it decreases the vapor pressure and shifts the equilibrium away from the liquid state, which is essentially boiling. Note that this is different from evaporation since the liquid water is not using heat from an external source to vaporize. You can also see this in daily life, for example, in that water boils at a different temperature on mountains due to pressure difference.