Messenger RNA (mRNA)

Definition

Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA to the ribosome, where proteins are synthesized. It plays a crucial role in the process of transcription, where the DNA sequence is copied into an RNA format, and serves as the template for translation, the process by which proteins are made based on the genetic code. mRNA is essential for gene expression and the flow of genetic information within a cell.

5 Must Know Facts For Your Next Test

1. mRNA is synthesized during transcription when RNA polymerase binds to the DNA template and assembles nucleotides complementary to the DNA strand.
2. The structure of mRNA includes a 5' cap and a poly-A tail, which protect it from degradation and assist in ribosome binding during translation.
3. In eukaryotic cells, mRNA undergoes splicing to remove introns and join exons before it can be translated into protein.
4. Each mRNA molecule is specific to a particular gene and encodes the information needed to produce one or more proteins.
5. The lifetime of mRNA varies; some are rapidly degraded while others persist longer, influencing how much protein is produced in a cell.

Review Questions

• How does the structure of mRNA contribute to its function in protein synthesis?
  • The structure of mRNA, which includes a 5' cap and a poly-A tail, plays an important role in its function during protein synthesis. The 5' cap helps protect the mRNA from degradation and facilitates its recognition by ribosomes for translation. The poly-A tail also aids in stability and transport out of the nucleus, allowing for efficient translation of the encoded genetic information into proteins.
• Discuss the differences between prokaryotic and eukaryotic mRNA processing and its implications for gene expression.
  • In prokaryotes, mRNA is typically translated immediately after transcription without any modifications, as there are no introns to splice out. In contrast, eukaryotic mRNA undergoes several processing steps including capping, polyadenylation, and splicing before it can be translated. This complexity allows for greater regulation of gene expression in eukaryotes, as different splice variants can produce different proteins from the same gene, impacting cellular functions significantly.
• Evaluate the impact of mRNA mutations on protein synthesis and potential consequences for cellular function.
  • Mutations in mRNA can lead to changes in the codon sequences that may result in altered amino acids being incorporated into proteins, potentially affecting their structure and function. For example, a single nucleotide change could lead to a missense mutation that results in an amino acid substitution, while a frameshift mutation might create a completely different protein altogether. These changes can disrupt normal cellular processes, leading to diseases or dysfunction if critical proteins are affected.

Related terms

Transcription: The process by which the information in a DNA sequence is copied into a complementary RNA sequence.

Ribosome: A molecular machine in the cell that synthesizes proteins by translating the sequence of mRNA into a specific amino acid chain.

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