The central dogma

Definition

The central dogma of molecular biology is a framework that describes the flow of genetic information within a biological system. It outlines the processes of transcription and translation, where DNA is first transcribed into RNA and then translated into proteins, which are essential for various cellular functions. This concept underscores the relationship between genes and the proteins they encode, highlighting how genetic instructions are utilized to produce functional biomolecules.

5 Must Know Facts For Your Next Test

1. In prokaryotes, transcription occurs in the cytoplasm as there is no nucleus, while in eukaryotes, it takes place in the nucleus before the mRNA is transported to the cytoplasm for translation.
2. Eukaryotic mRNA undergoes processing, including capping and polyadenylation, before it can be translated, unlike prokaryotic mRNA which is often ready for translation immediately after transcription.
3. The central dogma emphasizes that while information flows from DNA to RNA to protein, certain exceptions exist, such as reverse transcription in retroviruses.
4. Transcription factors play a crucial role in initiating transcription by binding to specific DNA sequences and recruiting RNA polymerase.
5. The accuracy of transcription and translation is vital for maintaining cellular function and preventing diseases caused by genetic mutations.

Review Questions

• How do the processes of transcription and translation differ between prokaryotes and eukaryotes?
  • In prokaryotes, transcription and translation occur simultaneously in the cytoplasm since they lack a nucleus, allowing for rapid protein synthesis. Conversely, in eukaryotes, transcription takes place in the nucleus where pre-mRNA undergoes several processing steps like splicing, capping, and polyadenylation before being transported to the cytoplasm for translation. This separation allows for more complex regulation of gene expression in eukaryotic cells.
• What role do transcription factors play in regulating gene expression within the framework of the central dogma?
  • Transcription factors are proteins that bind to specific DNA sequences to regulate the transcription of genes. They can either promote or inhibit the recruitment of RNA polymerase to a gene's promoter region, thereby controlling whether a gene is expressed. This regulation is crucial for cellular responses to environmental changes and developmental processes, ensuring that proteins are produced only when needed.
• Evaluate how understanding the central dogma influences modern biotechnological applications such as gene therapy.
  • Understanding the central dogma has revolutionized biotechnological applications like gene therapy, where faulty genes can be corrected or replaced with functional ones. By targeting specific genes through techniques such as CRISPR-Cas9, scientists can manipulate DNA to produce desired RNA and ultimately proteins that can restore normal function in diseased cells. This knowledge not only helps develop treatments for genetic disorders but also enhances our ability to design targeted therapies that can address various health issues at the molecular level.

Related terms

Transcription: The process by which the DNA sequence of a gene is copied into messenger RNA (mRNA) as the first step in gene expression.

Translation:

The process that occurs after transcription, where the mRNA is read by ribosomes to synthesize proteins based on the encoded information.

RNA Polymerase: An enzyme responsible for synthesizing RNA from a DNA template during transcription.