How do cells wrap presents?
Last year, I used cellular wrapping paper (the same material that makes cell membranes) for all of my family’s Christmas presents and they were delighted. This article spills some cellular-present-wrapping secrets and explains why cells wrap presents.
How do cells make wrapping paper?
Cellular wrapping paper is made up of lots of little individual units called phospholipids that look like lollypops (blobs with sticks on the end). If you were to pour a load of these lollypops into a jug of water, you would see something mega cool: the lollypops would naturally arrange themselves into a hollow sphere with blobs on the outside. Sometimes, this hollow sphere has two concentric lollypop layers, with blobs on the inside of the inner layer. This happens if the sphere has water inside it.
Why do Phospholipids make these spheres?
Blobs and water molecules absolutely love being next to each other. Sticks are not too fussy about where they go. The two-layered, water-filled sphere and the one-layered, non-water-filled sphere are the only possible arrangements where water molecules only touch blobs or other water molecules.
Why do blobs love water?
Understanding this requires knowledge of three types of chemical bond, shown in the image below. Chemical bonds are made when electrons from one atom get attracted to another atom, forcing the atoms to stick together, making a molecule. The bonding electrons hover in between the atoms that attract them.
Now, we can understand why blobs love water molecules – it’s because they both contain polar bonds. The slightly-negatively-charged sides of blob molecules and water molecules are attracted to the slightly-positively-charged sides of other blob molecules and water molecules! This is shown in the image below.
Why do blobs have polar bonds?
Polar bonds are made if one atom in a bond is more attractive to bonding electrons than the other atom, but not quite attractive enough to steal the electrons, which happens in ionic bonds. Attractive atoms have lots of protons in their nuclei, and their surrounding non-bonding electrons don’t take up too much space.
Water molecules are made of hydrogen atoms (not very electron-attracting because they only have one proton), and oxygen atoms (more electron-attracting because they have eight protons). Blobs are made of hydrogen atoms and other more-electron-attracting atoms like phosphorous and nitrogen. Sticks, on the other hand, are made from long chains of hydrogen and carbon atoms – both of these are equally attractive to bonding electrons.
And finally, why do cells wrap presents?
Cells wrap presents for the same reasons as humans – you want to give something to someone else without accidentally using it yourself beforehand! The main presents that cells wrap are hormones and neurotransmitters. The wrapped parcels are stored next to the cell membrane, and when the cell receives an appropriate signal, it releases the presents into the surrounding space. Wrapped presents are called vesicles and the releasing process is called exocytosis.
Have a very merry Christmas or anything else you celebrate!
I will leave you with a final picture of what Santa got in his Christmas stocking this year.