"DNA" - what is it, definition of the term
«DNA», deoxyribonucleic acid, is a double‑helical polymer of nucleotides that encodes the biological instructions for development, cellular function, and reproduction; in rodents such as rats and mice the molecule is organized into nuclear chromosomes that contain species‑specific genes, and its four‑base sequence directs protein synthesis through transcription and translation, thereby determining phenotypic traits.
Detailed information
Deoxyribonucleic acid, a polymer of deoxyribonucleotides, forms a double‑helical structure that stores hereditary information. Each monomer comprises a phosphate group, a deoxyribose sugar, and one of four nitrogenous bases—adenine, thymine, cytosine, or guanine. Hydrogen bonds between complementary bases stabilize the helix and enable precise replication.
In laboratory rodents, the genetic material is organized into a defined set of chromosomes. The laboratory mouse possesses 40 chromosomes, while the rat contains 42. Genome size differs modestly: the mouse genome spans approximately 2.7 gigabases, the rat genome about 2.9 gigabases. Both genomes are densely packed with protein‑coding genes, regulatory elements, and repetitive sequences.
Replication proceeds bidirectionally from multiple origins of synthesis. Initiation involves the assembly of a pre‑replication complex, activation of helicase, and recruitment of DNA polymerases. Proofreading exonucleases correct mismatches, preserving sequence fidelity across cell divisions.
Key techniques for analyzing the genetic material in these species include:
- Polymerase chain reaction for targeted amplification;
- High‑throughput sequencing for comprehensive genome interrogation;
- CRISPR‑Cas systems for precise genome editing;
- Fluorescence in situ hybridization for chromosomal mapping.
These methods underpin a wide range of experimental approaches. Gene knock‑out models generated in mice and rats elucidate gene function, support disease‑mechanism studies, and facilitate preclinical testing of therapeutics. Comparative genomics between the two species reveals conserved pathways and species‑specific variations, informing translational research.