Skip to main content
Super TutorResources
Chapter 5 of 10
Revision Notes

Molecular Genetics — Revision Notes

Tamil Nadu Board · Class 12 · Zoology

Molecular Genetics revision notes for Tamil Nadu Board Class 12 Zoology: 4 topics in quick points. Part of the Tamil Nadu Board Class 12 Zoology syllabus.

45 questions25 flashcards5 concepts

Interactive on Super Tutor

Studying Molecular Genetics? Get the full interactive chapter.

Quizzes, flashcards, AI doubt-solver and a step-by-step study plan — built for revision notes and more.

Try Super Tutor — Free

Free trial, no card needed.

An infographic summarizing the key characteristics of the genetic code: triplet, degenerate, unambiguous, universal, non-overlapping, and commaless, with brief explanations or examples for each proper
Super Tutor

Learn better with visuals Super Tutor pairs illustrations like this with notes and quizzes for Molecular Genetics.

Key Topics to Revise

1

5.1 Gene as the Functional Unit of Inheritance

  • A gene is the basic physical and functional unit of heredity carrying discrete hereditary information
  • Gregor Mendel (1860s) discovered genes but called them 'factors'; Wilhelm Johannsen coined the term 'gene' in 1909
  • Genes occupy specific positions (loci) on chromosomes and exist in alternate forms called alleles
2

5.2-5.3 Search for Genetic Material and DNA as Genetic Material

  • Friedrich Miescher (1869) isolated 'nuclein' from cell nuclei; renamed as nucleic acid by Altman (1889), now known as DNA
  • Griffith's transformation experiment (mentioned in class XI) showed unknown substance could transform bacteria
  • Avery, Macleod, and McCarty (1944) identified DNA as the transforming principle using in vitro experiments
3

5.4 Chemistry of Nucleic Acids

  • Nucleic acids are polymers of nucleotides, each composed of pentose sugar + nitrogenous base + phosphate group
  • DNA contains deoxyribose sugar; RNA contains ribose sugar - difference is one less oxygen in deoxyribose
  • Purines (A, G): double-ring structures; Pyrimidines (C, T, U): single-ring structures
4

5.5 RNA World

  • A typical cell contains about 10 times as much RNA as DNA
  • Fraenkel-Conrat and Singer (1957) demonstrated RNA as genetic material in TMV and other RNA viruses
  • 'RNA world' hypothesis proposed by Orgel, Crick, and Woese (early 1980s) suggests RNA was first genetic material on Earth

Get complete notes with diagrams and examples

Full Notes

Key Concepts

A gene is a discrete segmentMultiple experiments established DNA asDNA and RNA are polymers madeWatson and Crick (1953) proposedThe RNA world hypothesis proposes

Frequently Asked Questions

What are the important topics in Molecular Genetics for Tamil Nadu Board Class 12 Zoology?
Key topics in Molecular Genetics include 1 Gene as the Functional Unit of Inheritance, 2-5.3 Search for Genetic Material and DNA as Genetic Material, 4 Chemistry of Nucleic Acids, 5 RNA World. Study these first, then practise questions on each for the Tamil Nadu Board Class 12 board exam.
How should I revise Molecular Genetics for the Tamil Nadu Board Class 12 board exam?
Learn the core ideas first, then work through the 45 practice questions on Molecular Genetics. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

More resources for Molecular Genetics

All Tamil Nadu Board Class 12 Zoology Revision Notes

For serious students

Get the full Molecular Genetics chapter — start free.

Quizzes, flashcards, an AI doubt solver and a study plan for Tamil Nadu Board Class 12 Zoology. Free to start, no card needed.

Try Super Tutor Free
Try this chapter free