Definition
Cell, nucleus, chromosome
Genetics in this optional is not MBBS: it is variation, inheritance and population change.
- Cell: unit of life. Prokaryotes lack a membrane nucleus (bacteria); eukaryotes have one (humans).
- DNA packs around histones into chromatin; chromosomes are the dividing-cell form.
- Locus: the chromosomal address of a gene (example teaching notation: 2p22 — chromosome 2, short arm p, band 22).
Process
DNA structure and replication
- Double helix; strands anti-parallel (3′→5′ against 5′→3′).
- Backbone: deoxyribose + phosphate; bases A–T and G–C.
- Rosalind Franklin’s X-ray work made the helix visible; the Nobel story is a reminder of credit bias in science, not a genetics mechanism.
- Replication is semi-conservative: each daughter helix keeps one old strand.
- Leading strand is continuous; lagging strand is Okazaki fragments, primed by RNA, sealed by ligase after primers go.
Key points
Transcription and translation
- Transcription: RNA polymerase binds a promoter, copies a gene into RNA (initiation, elongation, termination).
- Translation: ribosome reads mRNA; tRNA brings amino acids; a polypeptide folds into protein.
- Exam line: DNA stores; RNA carries; protein does most of the cell’s work.
WRAP Exams coaching notes for UPSC Anthropology optional. Pair with the official syllabus when you need every heading in order.