MRNA

Definition

mRNA, or messenger RNA, is a single-stranded molecule that conveys genetic information from DNA to the ribosome, where proteins are synthesized. It plays a crucial role in the central dogma of molecular biology by acting as an intermediary that carries instructions for protein production, ensuring that the correct amino acids are assembled in the proper sequence to form functional proteins, which are essential for cellular functions and processes.

5 Must Know Facts For Your Next Test

1. mRNA is synthesized during the process of transcription, where a specific segment of DNA is copied into RNA by RNA polymerase.
2. In eukaryotic cells, mRNA undergoes processing, including capping, polyadenylation, and splicing before it can be translated into protein.
3. Each mRNA molecule contains codons, which are sequences of three nucleotides that correspond to specific amino acids in the protein sequence.
4. The stability and lifespan of mRNA can influence gene expression; some mRNAs degrade quickly while others persist longer in the cell.
5. Translation of mRNA occurs in the cytoplasm, where ribosomes read the codons and facilitate the assembly of amino acids into polypeptides.

Review Questions

• How does mRNA function as an intermediary in the process of gene expression?
  • mRNA serves as a crucial intermediary between DNA and protein synthesis. During transcription, a specific segment of DNA is transcribed into mRNA. This mRNA then carries the genetic code from the nucleus to the ribosomes in the cytoplasm, where it is translated into a protein. By conveying instructions from DNA to ribosomes, mRNA ensures that proteins are synthesized according to the genetic blueprint.
• What are some key differences between mRNA processing in eukaryotes compared to prokaryotes?
  • In eukaryotes, mRNA undergoes extensive processing before it can be translated into protein. This includes capping at the 5' end, addition of a poly-A tail at the 3' end, and splicing out introns while joining exons. In contrast, prokaryotic cells typically lack these modifications; their mRNA is often translated immediately after transcription without additional processing. This distinction highlights differences in gene expression regulation between these two types of organisms.
• Evaluate how variations in mRNA stability can impact cellular function and overall gene expression.
  • Variations in mRNA stability can significantly impact cellular function by influencing gene expression levels. If an mRNA molecule has a long lifespan, it can lead to higher protein production since it remains available for translation over an extended period. Conversely, if an mRNA is rapidly degraded, protein synthesis may decrease, potentially affecting vital cellular processes. Understanding these dynamics is crucial for insights into cellular responses to environmental changes and regulatory mechanisms controlling gene expression.

Related terms

DNA: Deoxyribonucleic acid, the molecule that contains the genetic blueprint for living organisms and is organized into genes.

Ribosome:

A molecular machine made of RNA and proteins that facilitates the translation of mRNA into a polypeptide chain, thus synthesizing proteins.

tRNA:

Transfer RNA, a type of RNA molecule that brings amino acids to the ribosome during protein synthesis, matching them with the corresponding codons on the mRNA.