Central Dogma: Videos & Practice Problems

The central dogma of biology describes the unidirectional flow of genetic 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 DNA. Additionally, reverse transcription allows RNA to synthesize DNA in specific scenarios. Understanding these mechanisms is crucial for grasping gene expression and the fundamental principles of molecular biology.

Central Dogma

The central dogma of biology describes the unidirectional flow of biochemical information from DNA to protein, emphasizing that this process is one-directional, meaning information cannot flow back from protein to DNA. This flow occurs through two main processes: transcription and translation.

Transcription is the first step, where RNA is synthesized using DNA as a template. The specific type of RNA produced during this process is messenger RNA (mRNA). This step is crucial as it converts the genetic information stored in DNA into a format that can be read and used by the cell.

The second step, translation, involves the synthesis of proteins based on the information encoded in mRNA. During translation, the mRNA sequence is read by ribosomes, which assemble amino acids into a polypeptide chain, ultimately forming a protein. Together, transcription and translation are often referred to as gene expression, as they are essential for the manifestation of genes into functional products, typically proteins.

It is also important to note that while DNA can be replicated—creating more DNA from existing DNA—there is a process known as reverse transcription. This process allows RNA to be used as a template to synthesize DNA, which is an exception to the typical flow described by the central dogma. However, the conversion of nucleic acids (DNA and RNA) into proteins is irreversible, meaning that once information is translated into protein, it cannot be converted back into nucleic acids.

In summary, the central dogma encapsulates the essential processes of transcription and translation, highlighting the flow of genetic information and the critical role of mRNA in protein synthesis. Understanding these processes is fundamental to grasping how genetic information is expressed in living organisms.

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.

Answer: (C)

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

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

Answer: (D)

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 protein. This process involves two key steps: transcription and translation. During transcription, DNA is used as a template to synthesize messenger RNA (mRNA). In the subsequent step, translation, the mRNA is used to build proteins. This flow of information is irreversible, meaning that once genetic information is converted into protein, it cannot revert back to nucleic acids. Understanding this concept is fundamental for grasping gene expression and the mechanisms of molecular biology.

What are the steps involved in the central dogma?

The central dogma involves two main steps: transcription and translation. In transcription, DNA serves as a template to synthesize messenger RNA (mRNA). This mRNA carries the genetic information from the DNA to the ribosome, where translation occurs. During translation, the mRNA is read by the ribosome to assemble amino acids into a polypeptide chain, forming a protein. These steps ensure the flow of genetic information from DNA to protein, which is crucial for cellular function and gene expression.

What is the role of mRNA in the central dogma?

Messenger RNA (mRNA) plays a crucial role in the central dogma of molecular biology. During transcription, mRNA is synthesized from a DNA template. This mRNA then carries the genetic information from the DNA in the nucleus to the ribosome in the cytoplasm. In the ribosome, the mRNA is read during the process of translation to assemble amino acids into a specific sequence, forming a protein. Thus, mRNA acts as an intermediary, conveying genetic information from DNA to the protein synthesis machinery.

Can genetic information flow from protein back to DNA?

No, genetic information cannot flow from protein back to DNA. The central dogma of molecular biology states that the flow of genetic information is unidirectional, from DNA to RNA to protein. Once the information is converted into protein, it cannot revert back to nucleic acids. However, in specific scenarios, RNA can be reverse transcribed back into DNA, a process known as reverse transcription. This exception does not violate the central dogma's principle that information does not flow from protein to nucleic acids.

What is reverse transcription and when does it occur?

Reverse transcription is the process by which RNA is used as a template to synthesize DNA. This process is catalyzed by the enzyme reverse transcriptase. Reverse transcription occurs in specific scenarios, such as in retroviruses like HIV, where the viral RNA genome is reverse transcribed into DNA, which then integrates into the host genome. This process is an exception to the central dogma's unidirectional flow of genetic information, allowing RNA to be converted back into DNA.