mRNA (messenger RNA)
Definition
Transcripts encoding proteins, synthesised in the nucleus from DNA templates and translated by ribosomes. mRNA molecules vary greatly in length (hundreds to thousands of nucleotides) and half-life, making some useful as tissue-type markers and others as potential degradation-rate markers.
- What it is
- A single-stranded RNA molecule copied from DNA that cells translate into protein.
- Size range
- Hundreds to thousands of nucleotides long, depending on the gene.
- Forensic use
- Identifies tissue type and can potentially estimate stain age through degradation patterns.
Common questions
What makes mRNA useful in forensic body fluid identification?+
mRNA shows which genes are active in a particular tissue, so its presence acts as a marker for tissue type. This lets forensic scientists identify whether a sample came from blood, saliva, semen, or other body fluids based on which mRNA molecules are present.
How does mRNA differ from DNA in forensic analysis?+
DNA tells you genetic identity, while mRNA tells you what genes are active in a specific tissue. mRNA has a much shorter lifespan than DNA because cells constantly break it down and make new copies as gene activity changes.
Why do different mRNA molecules work differently in degradation studies?+
mRNA molecules vary greatly in length and how long they survive in a cell before breaking down. Some degrade quickly and could help estimate how old a stain is, while others are stable enough to reliably identify tissue type.
Related terms
- RNase
- Ribonuclease enzymes that cleave RNA phosphodiester bonds. Present in blood plasma (RNase A family) and released from cells on death. The activity...
- Degradation index
- A ratio or combination of RNA abundance measurements designed to capture the state of degradation of a sample. Often calculated as the...
- Inter-individual variability
- Differences in RNA degradation rate between different donors' blood, arising from variation in RNase activity, blood cell composition, and haematological status. One...
- microRNA (miRNA)
- Small non-coding RNA molecules of approximately 18-24 nucleotides that regulate gene expression post-transcriptionally. Abundant in blood cells, relatively resistant to degradation compared...
- NanoString nCounter
- A hybridisation and digital counting platform that tallies individual mRNA molecules using fluorescent barcodes, avoiding amplification bias and enabling simultaneous profiling of...
- OSAC validation
- The framework for forensic assay validation published by the US Organisation of Scientific Area Committees, requiring demonstrations of sensitivity, specificity, mixture performance,...
- RT-PCR (reverse transcription PCR)
- A two-stage process: RNA is first reverse-transcribed into complementary DNA (cDNA), then the cDNA is amplified by PCR. Quantitative RT-PCR (RT-qPCR) measures...
- RT-qPCR
- Reverse-transcription quantitative PCR: a two-step assay in which RNA is first converted to complementary DNA (cDNA) by reverse transcriptase, then amplified and...
- Tissue-specific expression
- The pattern by which certain genes are transcribed at high levels in one tissue and at negligible levels in others, forming the...
Explained in these topics
- mRNA and microRNA Approaches to Stain AgeTranscripts encoding proteins, synthesised in the nucleus from DNA templates and translated by ribosomes. mRNA molecules vary greatly in length (hundreds to th...
- mRNA Profiling for Body Fluid IdentificationA single-stranded RNA molecule transcribed from a gene and translated into protein. Its presence in a cell reflects which genes are active in that tissue, maki...