In this video, we're going to begin our lesson on central dogma. And so the central dogma of biology refers to the unidirectional flow of biochemical information from DNA to protein. And so by unidirectional, what we mean is that it is a one-directional flow since the root uni means 1. And so information, biochemical information, will flow from DNA to protein. But because it's a one-directional flow, the biochemical information cannot flow backward from protein to DNA. Now this unidirectional flow of biochemical information from DNA to protein turns out it is a 2-step process that we have numbered down below, number 1 and number 2. And so the first step of the process is called transcription, which is the process that builds RNA by using DNA as the coding template. Now as we move forward in our course, we're going to learn more about the process of transcription. However, the specific type of RNA that's going to be built-in this case is going to be messenger RNA, which is also known as mRNA. And so we'll learn a lot about messenger RNA or mRNA as we move forward through our course.
Now in the second step of this process is translation, and translation is the process that builds protein by using the encoded messages of RNA, specifically mRNA or messenger RNA, which, again, we'll learn more about moving forward in our course. Now sometimes the process of transcription and translation are collectively referred to as gene expression. And so a gene is a small unit of DNA, recall from our previous lesson videos. And in order, for a gene to be expressed, its final product needs to be created, which in many cases, the final product will be a protein. And so if we take a look at our image down below, we can get a better understanding of this central dogma of molecular biology, which is, again, the unidirectional flow of biochemical information from DNA all the way to protein. And so, of course, what you can see here is that the process that uses DNA to build RNA is going to be transcription. So this is labeling the arrow that goes in this direction. And, of course, the second step of the process is going to be translation. And translation is the process that uses the RNA to build a protein. And so, again, the specific type of RNA that's going to be used in translation is called mRNA or messenger RNA, which we'll get to learn more about as we move forward in our course.
Now it is important to note that DNA can be replicated as we talked about in our previous lesson videos. DNA replication is the process of using DNA as the template to build even more DNA. And so it's kind of a cycle between DNA. And so DNA replication here, which we can add replication, of course is possible. Also, what is possible is a process that's referred to as reverse transcription, which is the process of using RNA, and using the RNA to build DNA. So RNA can be reverse transcribed into DNA, and so that is referring to this backward arrow right here. The process of using the messenger RNA to build DNA is possible in some scenarios, and this is called reverse transcription. And so what you can see here is that DNA can be used to build RNA, and RNA can be used to build DNA. And, of course, translation is the process that converts the messages of RNA into a protein. However, notice that this process here is unidirectional. It goes in one direction only. And so, the transfer of nucleic acid to protein is irreversible. And so, of course, the nucleic acids include DNA and RNA, but once nucleic acid information has been converted to protein, this process here is irreversible, and information from protein is not used to build nucleic acids. And so that is partly what the central dogma is referring to as well. And so this here concludes our brief introduction to the central dogma of biology and how it involves both transcription and translation. And as we move forward in our course, we're going to learn a lot more about each of these processes, transcription and translation. So I'll see you all in our next video.
