DNA Structure and Genetic Markers: Foundations (UGC-NET Unit III)

UGC-NET Forensic Science Unit III drill on DNA structure and the genetic markers used in forensic identification, pitched at the foundations level. Covers the Watson and Crick double helix (Nature, 1953), nucleotide chemistry and base pairing (A with T by two hydrogen bonds, G with C by three), the 3 prime to 5 prime phosphodiester backbone, anti-parallel strand orientation, major and minor grooves, gene anatomy (exon, intron, promoter), nuclear genome size (about 3.2 gigabases), chromatin and histones, mitochondrial DNA (16,569 base pairs, maternal inheritance, no recombination, hypervariable regions HV1 and HV2), alleles and polymorphisms (SNP, VNTR, STR), CODIS-style tetranucleotide STR loci such as D3S1358 in non-coding regions, mitosis versus meiosis, Y-STR paternal lineage, STR mutation rates, and Chargaff base-composition rules. Indian context anchors at CDFD Hyderabad, CFSL DNA divisions, and NFSU MSc syllabus. Easy-band items calibrated for first-pass UGC-NET preparation and concept refresh.