Are cells made of atoms

"Do not think of what you see, but of what is necessary to produce the visible"(Benoit Almond Bread)

So now I have just noticed that I have used terms quite often that only the older readers of this site understand, but not the small ones. And to make the whole thing worse, I just wanted to start again - luckily I noticed it in time and can make up for my mistake with you right away. ...

Where do we start - with the smallest or the largest term? Well, let's take the smallest, there is still room upstairs :).

What is an atom?

Surely you have already noticed that you see the things that are further away much less precisely than the things that are much closer to you. So, for example, if you see a small bird on the road from afar, you can say that it is a bird, but you do not see what kind of bird it is. You can only recognize the exact colors of the plumage, the real size and proportions when you stand close enough to the bird. If you stand about 1 m away from your bird, you can see what kind of bird it is, but you still cannot say what the feathers look like in detail. You can only do this if you are either angry and poke a feather for the bird or pick up a feather that the bird itself has lost and can thus look at even more closely. Then you will see that the spring consists of many small "twigs" with small hooks that are hooked into each other like zippers. Unfortunately you can't get much closer to the feather to find out how the individual "branches" of the feathers are constructed. What you can do, however, is to look at small areas of the feather enlarged with a magnifying glass. This game can be continued much further and always find new techniques (microscopy techniques) to see or depict an even smaller section of the pen a little more precisely and larger. At some point you come across small "spheres" called atoms. These little spheres can be sorted according to their properties - one of the most important properties is the number of binding sites they can use to hold onto other atoms and the thickness of their belly. If you sort all the particles according to the thickness of their belly, you will find about 118 particles of different thickness (sometimes new such spheres are made), which are called the elements. You can find all elements sorted in the periodic table of the elements. Examples of such elements are gold, silver or copper. You can imagine these small spheres as small males that are of different thicknesses and have different amounts of arms, whereby elements have a maximum of 8 arms. Some of these elements have the same number of arms, but none of the atoms are equally thick. If an object, like a feather, consists not only of one element but of atoms of different elements, then this is called a chemical substance. For example, glass is a fabric or wood.
This is of course only a simplified model of an atom, because atoms actually have no arms and no belly, but an atomic nucleus (= the belly), which is always composed of the same types of spheres, the positively charged protons and the neutral (= not charged) neutrons. Strictly speaking, the number of protons and neutrons determines the size and weight of the atomic nucleus, but only the number of protons is important for distinguishing which element the atom is. That means that all atoms that have been found so far have a proton number between 1 and 118 inclusive. For every proton in an atomic nucleus, an atom has a negatively charged particle, the electron, which swims around the nucleus. The number of electrons that are furthest out are equal to the arms or the binding points. It is, however, the case that not all arms like to hold onto other atoms at the same time, but rather some arms prefer to hold onto other arms of their own atom and are very reluctant to get involved with other atoms.
Another way to imagine atoms is a very tiny solar system, where the sun is the atomic nucleus and the planets are the electrons and revolve around the sun. However, you should be aware that this atomic model (Bohr's atomic model) is only an idea that can be used to explain certain phenomena (things that occur in this way). The reality is much more complicated. Two examples: actually the electrons do not circle around the atomic nucleus, but there are different "shells" that describe the different "probabilities of location" of the electrons. And a second example is that electrons can be viewed not only as particles, but also as "waves". Understanding that exactly is not so important at the beginning. You just shouldn't be surprised if sometimes certain things don't go with your ideas.

What is a molecule?

Since atoms have free arms or free outer electrons, they can "hold on" to other atoms. And all atoms that do not have a full 8 outer electrons (except for hydrogen and helium, they already have their hands full with 2 outer electrons) would like to find other atoms to hold on to. Now it's not little arms but electrons that buzz around the atomic nucleus, so that the atoms can always "share" electrons with other atoms. For this, the distance between the atoms is reduced and both, or more atoms, hold on to the connected electrons with about the same strength, so that it looks like ONE particle to the outside, which is then called a molecule. There are also other cases: If one atom is much stronger than another, it can simply poke a whole electron, so that 2 "charged atoms" are created, which are no longer called atoms, but ions. There are also whole "molecules" that are missing an electron, or that have one too many, these are also called ions. An ion with one electron too few is simply positively charged and an ion with one electron too many is simply negatively charged.
How does it work now with the division of hands or electrons? The electrons not only buzz around the atomic nucleus, but also "rotate" around themselves and for this there are exactly two possibilities for each electron, the so-called spin. With the outer electrons it is the case that the first 4 possible outer electrons of an atom always have the same spin and therefore do not touch each other. All other outer electrons (outer electron 5-8), however, have the opposite spin, so that they like to form pairs with the first 4 outer electrons. These electron pairs often prefer to remain among themselves than to form new electron pairs with other atoms, but it is often possible to form compounds with outer electrons of other atoms. But this is only a marginal information for later explanations.

When it comes to objects made from a single element, the element decides an incredible number of properties. In the case of objects made up of several elements, the elements, on the one hand, but also the arrangement of atoms and molecules with respect to one another determine a large proportion of the properties. Examples of these properties are color, conductivity for heat and electricity, flammability, flexibility (= elasticity), density (weight of an object per size / volume), brittleness, strength, chemical resistance and so on.

What is a cell? (+ Bacterium and virus)

Every object and every living being is made up of molecules and ions. Some have more complicated structures with more different elements, others somewhat simpler ones. But what is the difference between life and non-life? As a child, everyone is fascinated by the fact that there are things in our everyday life to which we can clearly assign the characteristics to life. What does science say about it? Now science says that we can say this very clearly for all larger structures such as plants, dogs, chinchillas or cars and houses. But with smaller structures this is more difficult again. That is why the smallest unit of life, the cell, has been defined. A cell consists of many thousands of molecules and, like an atom, is a kind of building block from which every living being is built. These thousands of individual molecules work together in the same way as the organs in our body do, only in cells it is called the cell organelles. If a living being consists of only one single cell, it is called a single cell. If the living being has several cells, they are multicellular. This applies to all living things, including plants, animals and fungi. Funnily enough, there are also slime molds, for example, which both live individually and can also become multicellular creatures if they "want" to. So what characterizes such a cell? A living being always has:

  • a self-sustaining metabolism (it needs food and excretes processed food again)
  • an exchange of information with its environment (it can absorb, process and react to stimuli from its environment)
  • growth
  • the ability to reproduce
  • and the ability to evolve (mutation and selection - every offspring can bring about small changes)

Cells therefore always have a kind of shell, the cell membrane and plant cells even have a second shell, the cell wall. In addition, cells always have hereditary information, DNA or RNA, in their middle, which is somewhat differentiated from the rest of the cell. This genetic information is one (or more) very long molecule (s) that are made up of letters like a kind of text, with information for the rest of the cell that explains what needs to be done in order to live. Very often cells are much larger than most molecules and some can even be seen with the naked eye. But there are also very small cells and some are so small that they have space to hide in larger cells and thus make them sick. Some bacteria in particular can do that. Bacteria are tiny, single-celled animals that can be found all over the world - some help people with life, others make them sick or harm them, and still others take care of their own business. And then there are viruses. Viruses are not living beings, although they are very similar to unicellular organisms and even have genetic information. However, viruses are unable to reproduce or grow by themselves and they also have no metabolism. Viruses can only reproduce by injecting their genetic information into a living cell and the living cell then tinkering with a new virus, because the virus genetic information circumscribes the genetic information of the cell in such a way that the cell "thinks" that it has to build new viruses. The cell builds new viruses until it bursts and all the viruses get into the environment.