Central Dogma - Online Tutor, Practice Problems & Exam Prep

The central dogma of biology describes the unidirectional flow of biochemical information from DNA to protein, encompassing two key processes: transcription and translation. Transcription synthesizes messenger RNA (mRNA) from DNA, while translation converts mRNA into proteins. This process is irreversible; once nucleic acid information is transformed into protein, it cannot revert to nucleic acids. Additionally, DNA can replicate itself, and reverse transcription allows RNA to form DNA in specific scenarios. Understanding these processes is crucial for grasping gene expression and the fundamental mechanisms of molecular biology.

Central Dogma

In this video, we're going to begin our lesson on Central Dogma. The Central Dogma of Biology refers to the unidirectional flow of biochemical information from DNA to protein. By unidirectional, we mean that it is a one-directional flow since the root 'uni' means 1. Information will flow from DNA to protein, but because it's a one-directional flow, the biochemical information cannot flow backwards from protein to DNA. This unidirectional flow of biochemical information from DNA to protein is a 2-step process.

The first step of the process is called transcription, which builds RNA by using DNA as the coding template. As we move forward in our course, we're going to learn more about the process of transcription. The specific type of RNA that's going to be built, in this case, is messenger RNA, also known as mRNA. We'll learn a lot about messenger RNA as we move forward through our course. The second step of this process is translation.

Translation is the process that builds protein by using the encoded messages of RNA, specifically mRNA. Sometimes the processes of transcription and translation are collectively referred to as gene expression. A gene is a small unit of DNA, and for a gene to be expressed, its final product, often a protein, needs to be created. If we take a look at our image, we can get a better understanding of this central dogma of molecular biology, which is the unidirectional flow of biochemical information from DNA all the way to protein.

Transcription uses DNA to build RNA, and translation uses RNA to build protein. It is important to note that DNA can be replicated. DNA replication is the process of using DNA as the template to build more DNA. It is also possible for RNA to be reverse transcribed into DNA, a process called reverse transcription. Reverse transcription is the process of using RNA to build DNA.

Translation converts the messages of RNA into protein. However, this process is unidirectional, going in one direction only. The transfer of nucleic acid to protein is irreversible. Once nucleic acid information has been converted to protein, information from protein is not used to build nucleic acids. That is partly what the central dogma refers to. This concludes our brief introduction to the central dogma of biology and how it involves both transcription and translation.

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.

According to the central dogma, what is the intermediate molecule involved in the flow of information in a cell that should go in the blank? DNA → ________ → Proteins

• A. Ribosome.
• B. rRNA.
• C. mRNA.
• D. tRNA.

The full process by which genotype becomes expressed as phenotype is called:

• A. Transcription.
• B. Translation.
• C. DNA Replication.
• D. Gene expression.

Here’s what students ask on this topic:

What is the central dogma of molecular biology?

The central dogma of molecular biology describes the unidirectional flow of genetic information from DNA to RNA to protein. This process involves two main steps: transcription and translation. During transcription, DNA is used as a template to synthesize messenger RNA (mRNA). In translation, the mRNA is then used to build proteins. This flow of information is irreversible, meaning that once the information is converted into protein, it cannot revert back to nucleic acids. Understanding this concept is fundamental for grasping how genes are expressed and how genetic information is utilized within cells.

What are the steps involved in the central dogma?

The central dogma involves two key steps: transcription and translation. In transcription, DNA serves as a template to synthesize messenger RNA (mRNA). This process occurs in the nucleus of eukaryotic cells. The mRNA then exits the nucleus and enters the cytoplasm, where translation occurs. During translation, ribosomes read the mRNA sequence and use it to assemble amino acids into a polypeptide chain, forming a protein. These steps are crucial for gene expression, allowing the genetic information stored in DNA to be converted into functional proteins.

What is the role of mRNA in the central dogma?

Messenger RNA (mRNA) plays a critical role in the central dogma of molecular biology. It acts as an intermediary between DNA and protein synthesis. During transcription, mRNA is synthesized from a DNA template. This mRNA carries the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm, where translation occurs. In translation, the mRNA sequence is read by ribosomes to assemble amino acids into a specific protein. Thus, mRNA is essential for transferring genetic information from the nucleus to the site of protein synthesis.

Can RNA be reverse transcribed into DNA?

Yes, RNA can be reverse transcribed into DNA through a process known as reverse transcription. This process uses an enzyme called reverse transcriptase to synthesize complementary DNA (cDNA) from an RNA template. Reverse transcription is not part of the central dogma's unidirectional flow but occurs in specific scenarios, such as in retroviruses like HIV. Understanding reverse transcription is important for studying viral replication and certain biotechnological applications, such as creating cDNA libraries for gene expression studies.

Why is the flow of information from nucleic acids to proteins considered irreversible?

The flow of information from nucleic acids (DNA and RNA) to proteins is considered irreversible because, once the genetic information is translated into a protein, it cannot be converted back into nucleic acids. This unidirectional flow is a fundamental principle of the central dogma of molecular biology. Proteins do not serve as templates for the synthesis of nucleic acids. This irreversibility ensures that the genetic information is faithfully transmitted and expressed without the risk of back-conversion, maintaining the integrity of the genetic code.