MRNA

Definition

mRNA, or messenger RNA, is a type of RNA that serves as the intermediary between DNA and protein synthesis. It carries genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm, where proteins are made. This process is essential for translating the genetic code into functional proteins, which are crucial for various biological processes.

5 Must Know Facts For Your Next Test

1. mRNA is synthesized during transcription by RNA polymerase, which reads the DNA template strand.
2. The structure of mRNA includes a 5' cap and a poly-A tail, which protect the molecule from degradation and assist in translation.
3. In eukaryotes, mRNA undergoes processing, including splicing, where introns are removed and exons are joined together.
4. Each mRNA molecule can be translated multiple times, allowing for efficient protein production from a single gene.
5. The sequence of codons in mRNA determines the order of amino acids in a protein, thus dictating its structure and function.

Review Questions

• How does mRNA function as a bridge between DNA and protein synthesis?
  • mRNA functions as a bridge between DNA and protein synthesis by carrying genetic information transcribed from DNA to the ribosomes, where proteins are synthesized. During transcription, RNA polymerase reads the DNA template and produces a complementary mRNA strand. This mRNA then moves from the nucleus to the cytoplasm, where it serves as a template for translating the sequence of nucleotides into a specific amino acid chain at the ribosome.
• Discuss the role of mRNA processing in eukaryotic cells and its importance for translation.
  • In eukaryotic cells, mRNA processing includes several steps such as capping, polyadenylation, and splicing. The 5' cap helps stabilize the mRNA and is involved in the initiation of translation, while the poly-A tail protects the molecule from degradation. Splicing removes non-coding regions (introns) and joins coding sequences (exons), ensuring that only the necessary information is translated into proteins. This processing is crucial for producing mature mRNA that can be effectively translated.
• Evaluate how mutations in mRNA can impact protein synthesis and cellular function.
  • Mutations in mRNA can lead to changes in the codon sequence that may result in altered or nonfunctional proteins. For instance, a point mutation might cause a single amino acid change in a protein, potentially affecting its structure and function. In some cases, mutations can create stop codons prematurely, leading to truncated proteins. Such alterations can disrupt cellular processes and contribute to diseases or malfunctions at various biological levels.

Related terms

Transcription: The process of copying a segment of DNA into RNA, specifically mRNA, which will then be used to direct protein synthesis.

Ribosome: The cellular machinery where protein synthesis occurs, translating mRNA sequences into polypeptide chains.

Codon: A sequence of three nucleotides in mRNA that corresponds to a specific amino acid or a stop signal during protein synthesis.