Molecular Biology with Idhant
The marvelous molecule: proteins!
Hey guys! Before I begin the amazing process of protein synthesis, I just want to thank all of you. Thank you for reading my articles. Thanks for favoriting them. Thank you for helping me hit my ‘quarter-way there’ milestone on my road to 100 followers. And thank you for sticking with me since my ‘Acid Attack on Pi Day’ article. Because now I know over thirty digits of pi.
And now, let’s jump right in. What is a protein? Well, it is one of the four vital biomolecules in your body, along with carbohydrates, lipids, and nucleic acids. Proteins make up a lot of stuff in your body. And by a lot, I mean A LOT. For example, they make up antibodies, enzymes, parts of your blood, and many other things. Here is a quote from The Nutrition Source;
Protein is found throughout the body — in muscle, bone, skin, hair, and virtually every other body part or tissue. It makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood. At least 10,000 different proteins make you what you are and keep you that way.
If you want to read more from this site, click on the link above. But we’re moving on. Right now, we are talking about nucleic acids. DNA and RNA fall under the catergory of nucleic acids, and I have a seperate post on those two. Check that out after this one, because it’s awesome! But I’ll give an overview of the importance of DNA and RNA. DNA is usually double stranded, and is replicated to create RNA. How is it replicated? That we shall discuss in a moment. RNA carries out DNA’s commands and goes through translation, a process which which we shall also discuss in some time.
But this translation thingy sounds interesting, right? Well, probably not at first glance, but trust me, it’s really fun! Now, translation is a step of protein synthesis, but it comes after a step called transcription. During transcription, the DNA is replicated and the information embedded in it’s base pairs in duplicated. But finally, we can talk about my all-time favorite part of DNA replication: the ‘how.’
Remember those little bundles of proteins in your body called enzymes? They do a lot of important things. But we’ll focus on only one for now: DNA replication. There are four key players in DNA replication, but we’ll get to that in a moment. Why exactly does DNA replication need to occur, though? Good question, me!
So DNA needs to be replicated because without that happening, you can say bye-bye to your precious RNA, because it requires a copy of the original DNA blueprint in order to be made. And without RNA, no proteins! And now let’s delve into the magicians performing this trick. Nope, it’s not mini Harry Houdini. It’s those tiny bundles of proteins; enzymes!
Helicase is like the opening enzyme. It unravels the DNA by unzipping the base pairs. Afterwards, Primase places these things called primers across the unzipped DNA and these primers halp another enzyme, DNA polymerase. DNA polymerase builds on top of the primers & creates a new strand of DNA. Finally, Ligase glues together these new base pairs, and they are called Okazaki Fragments. In reality, these Okazaki Fragments aren’t really base pairs, but instead parts on the lagging strand of the DNA. We’ll talk about that in a future post, though. Onwards!
When the enzymes all collaborate, you get a result of two identical DNA strands. The duplicated one is called the ‘template DNA strand.’ This template DNA strand then gets built on again; another enzyme called RNA polymerase starts building off the template DNA strand and makes RNA; a single-stranded masterpiece! Let’s learn more about RNA now!
Welcome to the world of RiboNucleic Acids. There are three kinds of RNA:
- mRNA, or messenger RNA: This is the strand created by the RNA polymerase
- rRNA, or ribosomal RNA: Makes up the ribosomes, an important cell organelle, which we will get to in a moment
- tRNA, or transfer RNA: Carries amino acids to create proteins
If it sounds difficult to remember, I’ll explain in detail later. Just hang in there, as we fly through the cell’s nucleus. *that sounded so much better in my head*
mRNA travels to an organelle called the ribosomes. Why does mRNA go to the ribosomes? To get translated into a chain of amino acids, or a wonderful protein! How? Let’s dive in!
Remember how RNA leaves the nucleus? So once it leaves the nucleus, the mRNA goes to the ribosomes. In the ribosomes, made fully out of rRNA & proteins, the mRNA meets another kind of RNA: tRNA! Transfer Ribonucleic Acid, or tRNA, carries two things: an amino acid, and a thing called an anticodon. This anticodon contains three base pairs that can match up with three of the mRNA base pairs. The mRNA base pair are translated in groups of three, each group called a codon. I am aware that you probably won’t be able to visualize this if you are a beginner, so use this diagram.
At the end of a protein chain, there is a codon that codes for STOP. What does this stop mean? It means that the chain of amino acids have ended. In a protein chain, the STOP isn’t included in the chain because it stopped the production of more peptide bonds between amino acids. And now, after the STOP codon is translated, we have an official protein! Or do we?
What are these protein chains called? Well, remember those peptide bonds? They fasten the amino acids together. Named after these peptide bonds, the chains of amino acids are conveniently called polypeptide chains. Polypeptide chains then go through something called protein folding, which we’ll get to in a moment, to become a full fledged structural or functional protein. Any one protein consists of one or more polypeptide chains. How are proteins folded into their full potential? Time for exploration!
Polypeptide chains aren’t exactly that useful after they exit the ribosomes. All the amino acids are in a linear structure, after all. They need to be folded so that they can become useful bundles of amino acids. When a polypeptide chain leaves the ribosome at first, it is in the primary, or linear, stage. But once it gets folded into another shape, it can be used as a structural protein.
First, it folds into either an alpha-helix or beta-sheets. When it is in this stage, it is in the secondary stage. Afterwards, it folds a bit more so that similar amino acids with similar chemical properties are together. This is the tertiary stage. A protein in tertiary stage is finally able to be a functional protein, too! But there’s more. Remember how a protein can consist of over one polypeptide chain? If this is true for the protein you are building, it needs to combine with other polypeptide chains to form a protein in its quaternary, or final, stage. And now, it is an OFFICIAL protein.
Here’s a warning: It took multiple Youtube videos, some intense researching, and A WHOLE MANGA GUIDE to get all this information. And now I’m spitting it all out in a less then ten minute read. So do take all this information with a thought, then a huge thought, and then a huge-er thought, because 101% of it is super-simplified. And I simplified it because if I tried to say any of this in it’s true nature, even I wouldn’t understand what I’m saying, and also, it would sound like this to any other normal human being:
BLAH BLAH BLAH BLAH proteins BLAH BLAH BLAH transcription BLAH BLAH BLAH BLAH BLAH BLAH enzymes BLAH BLAH active site BLAH BLAH BLAH chemical reactions BLAH BLAH BLAH BLAH BLAH alpha-helix BLAH BLAH polypeptide thingy… You get the point!
And two more words: thank you. As I mentioned, it took quite a bit of hard work to learn this stuff. Also, side note, while you read this, every single one of your cells was doing this literally EVERY SINGLE NANOSECOND. Why? Because if cell stops making proteins…
It dies.
And that leads us to why proteins are so important! Proteins are the language of cells, the base for cells, the food-supplier for cells… Basically the EVERYTHING for cells! Whether you are multicellular or unicellular, an autotroph or a heterotroph, whether you breathe through aerobic or anaerobic respiration, whether you are a prokaryote or a eukaryote, you need proteins to survive, because they carry out so many life processes!
And again, thank you for reading, and supporting me!
