Chemistry
Hydrogen and helium (two nonmetals), make up about 99% of ordinary matter in the observable universe by mass.
Living organisms are composed almost entirely of the nonmetals hydrogen, oxygen, carbon, and nitrogen
Periodic Table
Columns in the periodic table form similar valence electrons. If you are above or below another element in the table, you can make similar molecules with all the same other atoms.
For example, silicon is right below. So every molecule we can make with carbon can also be made with silicon
- This is why many Sci-fi movies have life forms that are silicon based, rather than carbon based. This rationale is a bit weak however, since carbon is much more ubiquitous than silicon is.
Molecules
In a molecule, electrons are not confined to their own atoms. They can move around with ease if the right atoms are connected in the right way.
- Sometimes the movements are so divisive as to polarize the molecule, and sometimes not quite so much that the molecule is not very polar at all. The important thing to keep in mind is that molecules will interact with each other depending on these degree of electrical interactions.
- A lot of how a protein behaves is due to electrical interactions.
Protein
Each protein is a molecule that is composed of chains of amino acids.
- Using a particular set of atoms as building materials – which are carbon, nitrogen, oxygen and maybe a dash of sulfur – we can construct an amino acid. Start putting them together, and our chains will start to spiral and flatten due to electrical interactions between electrons that move around a molecule and expose positive regions.
- Chain enough amino acids and form enough spirals, and the result is an immensely complicated and massive molecule known as a protein.
Baking example
When mixing incredients for a cake, sometimes we have oil (large and electrically neutral) and water (small and highly charged). Naturally these 2 ingredients won't mix, but we can mix them if we add an egg. The reason this works is because of the egg's high protein content.
- Proteins are amphiphilic, meaning that they have segments that prefer mixing with oil and segments that prefer mixing with water. When mixing an egg, the proteins start to unravel, scooping the ingredients in the water and the ingredients in the oil, creating one large oop.
- This property makes eggs an emulsifier, also known as a binding agent.
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