Ribosomes. How do they work?
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Ribosomes are essentially protein factories for your cells. Proteins are made up of building blocks called amino acids. The ribosomes take individual amino acids and link them together in a specific order to create a finished protein. How do the ribosomes know which amino acids and in which order they need to be placed? They use RNA, which is translated from DNA. Your DNA holds the blueprint for all of the proteins in your body. When a cell needs to make a protein, the DNA is translated into RNA which can then leave the nucleus of the cell and tell the ribosome what kind of protein to make.
There are many different types of RNA. mRNA (messenger RNA) is the type of RNA that tells the ribosome what to do. tRNA (transfer RNA) is the type of RNA that retrieves the individual amino acids and brings them to the ribosome in the order that is dictated by the mRNA. The ribosome just links them together.
This is why you hear people talk about the COVID vaccine “altering your body’s DNA.” The mRNA based vaccines carry mRNA of viral particles. The ribosomes then take the mRNA (they don’t care if your body made it or not) and create the appropriate protein. In the case of the vaccines, these proteins are viral proteins. Enough of the virus that your body can recognize it if/when you get truly infected, but not so much of the virus that you actually get the infection itself. Your body’s native DNA is left untouched.
Let’s say that your cell is a family bakery. Each cell/bakery has a family hierloom called “The grandma’s special and secret recipe book”. That recipe book has hundreds of recipies. In this analogy, the grandma’s recipebook is your DNA and hundreds of recipes tell your cell how to make hundreds of different proteins. Now imagine that in that bakery/cell you can find a lot of pastry chefs and they all have to make various pastries. It would be slow, inefficient, and dangerous to give the whole recipebook to a chef for him to keep until he’s finished making his pastry, so your cell invested in a copy machine that copies a specific recepie for each pastry chef. Let’s say that one chef wants to make an applie strudel, and one wants to make a chocolate croissant. The copy machine makes one copy of the strudel recipe and one copy of crossaint recipe and gives the copies to their respective chef. Now there’s no holdup if multiple chefs whant to make multiple pastries.
What we’ve just described is the first part of the protein synthesis. As we’ve said, the recipebook is our DNA, and each cell has only one DNA. The chefs in our story are ribosomes. They are tiny workers that use the recipebook/the DNA to make different proteins/pastries that our cells need. However, because we have one DNA and multiple ribosomes, we can’t afford to give the whole DNA to one ribosome at a time because we could only make one protein at a time. To speed up the protein production, the cell invested in the copy machine, an enzyme called RNA polymerase. It makes a copy from the recipebook/DNA and sends that copy to its respective chef. These copies are messenger RNA molecules or mRNA for short. These copies make it possible for more chefs/ribosomes to make many different pastries/proteins.
Now let’s get back to our pastry shop. It turns out that our grandma was so secretive of her recipe that she developed a secret code to protect her recipe. She developed a code in which she gave every ingredient a three letter code using only four letters. These letters are: A, G, T, and C. So, for example,
1 cups of sugar is ATT
1 cup flower is GCT
1 cup milk is CCG
Etc
Chefs are, thakfully, skilled in translating her secret code so they can perfectly make grandma’s recipes.
Outside of our fantasy world, one thing holds true – the DNA is truly made up of four letter, or as biologists call them, bases. These are adenine (A), gvanine (G), thymine (T), and cytosine (C). The DNA, and subsequently the mRNA carry information on how to make a protein in that code (although, mRNA uses a different letter, uracil (U) instead of thymine (T)). The ingredients in our analogy are amino acids in the real life. Amino acids are quite literally ingredients that make up proteins and they give them different properties and function. Each triplet, or a group of three letters, corresponds to a different ingredient/amino acid. In the real world, the ingredients are:
ATT instead of sugar is the amino acid phenylalanine
GCT instead of flowe is the AA serine
CCG instead of milk is the AA proline
Ribosomes then add all those ingredients/amino acids together and make up another pastry/protein
This is a kid friendly, albeit a pretty simplified version of the process of protein synthesis. How ribosomes know what to add and how they add it is a bit more complicated, but if you’re interested i can explain. Of course, if you have further questions, pleace ask.
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