Messenger RNA

Definition

Messenger RNA (mRNA) is a single-stranded RNA molecule that carries genetic information from DNA to the ribosome, where proteins are synthesized. This process is essential because mRNA acts as a template for assembling amino acids in the correct order to form proteins, which are crucial for cellular functions and structures.

5 Must Know Facts For Your Next Test

1. mRNA is synthesized during transcription, where an RNA polymerase enzyme reads a DNA template and constructs a complementary RNA strand.
2. The structure of mRNA includes a 5' cap and a poly-A tail, which protect it from degradation and help in the initiation of translation.
3. Different mRNA molecules can carry instructions for different proteins, allowing cells to produce a wide variety of proteins based on their needs.
4. mRNA undergoes splicing after transcription, where introns (non-coding regions) are removed and exons (coding regions) are joined together before it exits the nucleus.
5. The lifespan of mRNA can vary significantly; some may be quickly degraded while others are stable and can be translated multiple times to produce many protein copies.

Review Questions

• How does messenger RNA play a role in the flow of genetic information from DNA to protein synthesis?
  • Messenger RNA serves as the intermediary between DNA and protein synthesis by carrying the genetic code from the nucleus to the ribosome. During transcription, mRNA is created by copying the DNA sequence of a gene. Once mRNA reaches the ribosome, it acts as a template for translating that code into a specific sequence of amino acids, ultimately forming a protein.
• Discuss the significance of the modifications made to messenger RNA after its transcription and before translation.
  • After transcription, messenger RNA undergoes several critical modifications, including the addition of a 5' cap and a poly-A tail. These modifications protect mRNA from degradation and facilitate its recognition by ribosomes for translation. Additionally, splicing occurs where introns are removed, and exons are joined together, ensuring only the coding sequences are included in the final mRNA that will direct protein synthesis.
• Evaluate how the discovery of messenger RNA has influenced our understanding of genetics and molecular biology.
  • The discovery of messenger RNA has significantly shaped our understanding of genetics by clarifying how genetic information is expressed within cells. It highlighted the central dogma of molecular biology—DNA is transcribed into RNA, which is then translated into proteins. This concept has led to advancements in genetic engineering, biotechnology, and our comprehension of diseases related to protein synthesis errors, emphasizing the crucial role mRNA plays in cellular function and heredity.

Related terms

DNA:

Deoxyribonucleic acid, the molecule that contains the genetic blueprint for all living organisms, composed of two strands forming a double helix.

Ribosome: The molecular machine in cells that synthesizes proteins by translating mRNA into polypeptide chains.

Transcription: The process by which the information in a segment of DNA is copied into mRNA, serving as the first step in gene expression.