The DNA of the cell contains the blueprints for all the proteins in the body. These blueprints become proteins with the help of RNA and ribosomes. Follow along with this lesson to learn about the two major phases of protein synthesis: transcription and translation.
Did you know that your cells have an architect living inside them? We call this architect DNA, or deoxyribonucleic acid. You’ve probably heard this term from cop shows where DNA left behind by a suspect becomes the undeniable proof that links him to the crime.Well, DNA is not only a form of identification, it’s also where the master blueprints for protein synthesis are drawn up.
This is a very important job because proteins do a lot for you. They do everything from helping to build structures to supporting your immune system. In this lesson, we will take a look at how the information from your DNA is read and interpreted to make, or synthesize, proteins.When we look inside the nucleus of your cells, we see that the DNA architects have drawn up a ton of blueprints, making a unique design for each of the 1000s of different proteins in your body. Does your body need a specialized protein called an enzyme? Your DNA has the blueprint to make that. Does it need a structural protein to build a body tissue? DNA has that blueprint on file, as well.The tricky part is that DNA is found inside the nucleus of the cell, but the ribosome, which is the protein manufacturing factory where the protein is actually put together, is located outside the nucleus in the gel-like cytoplasm.
So your cells need a way to get the information from the DNA to the ribosome. This task is carried out by RNA, or ribonucleic acid. RNA comes in different varieties that help the process along during the two major phases of protein synthesis. Let’s take a look at these phases.
The first is called transcription.
This is the process by which information in a DNA is copied into a new format. Now, I don’t know about you, but when I think about the word transcription, I get an image of a secretary taking notes in shorthand. The secretary then transcribes the notes written in shorthand into a typewritten letter.
That’s pretty close to what’s going on here in the nucleus of the cell, but instead of words and a secretary, we have blueprints from the DNA and a messenger RNA, or mRNA. The mRNA acts like the secretary and takes the information from the DNA and transcribes, or rewrites it, into a different format. The format is different, but the information is the exact same. In other words, it’s still in the same language.
This moves us one step closer to making a protein, but there’s a problem.
You see, this information, even in its new format, is in a language only understood by nucleic acids, like DNA and RNA. What we need is for this information to be converted or translated into the language of protein. This is what happens during translation, which is the process by which ribosomes create proteins from information contained in mRNA.
This happens out in the cytoplasm because that’s where ribosomes live.The mRNA leaves the nucleus and attaches to the ribosome. At this time, we see a different type of RNA come on the scene called transfer RNA, or tRNA.
This type of RNA is carrying an amino acid, which is a basic building block of protein. tRNA’s job is to carry the appropriate amino acid to the ribosomes. So, how does the tRNA know it has the appropriate amino acid? Well, as it turns out, tRNA are good at reading or translating something called a codon, which is a three-base sequence on the mRNA strand.
You see, the tRNA structure not only has an amino acid attached to it, it also has an anticodon, which is three-base sequences on the tRNA. Think of it as the mRNA having the code (codon) and tRNA having the decoder ring (anticodon) that translates the information. This anticodon is attracted to the matching codon, and when they pair up, the amino acid from the tRNA is transferred to the mRNA strand. As more tRNA come into the ribosome, the chain of amino acids grows to become the protein it was meant to be.
Let’s review. DNA, or deoxyribonucleic acid, is where the blueprints for protein synthesis are drawn up.
A ribosome is the protein manufacturing factory where the protein is actually put together. Because DNA is in the nucleus and ribosomes are in the cytoplasm, your cells need to rely on RNA, or ribonucleic acid, to transfer the information.The first phase of protein synthesis is known as transcription, which is the process by which information in DNA is copied into a new format.
Here, we see that the blueprints from the DNA are transcribed and carried out of the nucleus by a messenger RNA, or mRNA.The mRNA meets up with a ribosome, and we start the second phase of protein synthesis known as translation, which is the process by which ribosomes create proteins from information contained in mRNA. At this time, transfer RNA, or tRNA, translates the codon on the mRNA strand.
The tRNA pairs its anticodon with the codon. When they are paired up, the amino acid from the tRNA is transferred to the mRNA strand, and the new protein grows.
You should have the ability to do the following after this lesson:
- Explain the roles of DNA, ribosomes and RNA in protein synthesis
- Describe the phases of transcription and translation