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Molecular Basis of Inheritance — Revision Notes

ICSE · Class 12 · Biology

Molecular Basis of Inheritance revision notes for ICSE Class 12 Biology: 4 topics in quick points. Part of the ICSE Class 12 Biology syllabus.

130 questions45 flashcards4 formulas & key relations5 concepts

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A flowchart illustrating the sequential steps involved in DNA fingerprinting (DNA profiling), from DNA isolation to the detection of hybridized DNA fragments, including restriction digestion, gel elec
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Key Topics to Revise

1

Genes and the Nature of Genetic Material

  • The term gene was coined by W. Johannsen in 1909.
  • A gene is a unit of information that directs the activity of the cell or organism during its lifetime and passes its message to progeny when the cell or organism divides or reproduces.
  • George W. Beadle and Edward L. Tatum proposed the one gene-one enzyme hypothesis in the early 1940s.
2

DNA and RNA: Structure and Base Composition

  • Nucleic acids are polymers made of nucleotides.
  • Each nucleotide has a nitrogenous base, a pentose sugar and phosphoric acid.
  • DNA contains deoxyribose sugar, while RNA contains ribose sugar.
3

DNA Double Helix and Packaging of DNA

  • Franklin and Wilkins provided X-ray diffraction evidence for the helical structure of DNA.
  • The DNA helix is long and thin, with a uniform diameter of 20 Å.
  • The distance between successive nucleotides is 3.4 Å.
4

Replication of DNA

  • DNA replication is essential for cell division.
  • The three hypotheses of replication are conservative, dispersive and semi-conservative.
  • Semi-conservative replication was proposed by Watson and Crick in 1953.

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Full Notes

Key Concepts

A gene is a unitDNA is the main genetic materialLive RDNA isolated from heatT2 bacteriophages were labelled with 35S

Frequently Asked Questions

What are the important topics in Molecular Basis of Inheritance for ICSE Class 12 Biology?
Key topics in Molecular Basis of Inheritance include Genes and the Nature of Genetic Material, DNA and RNA: Structure and Base Composition, DNA Double Helix and Packaging of DNA, Replication of DNA. Study these first, then practise questions on each for the ICSE Class 12 board exam.
How should I revise Molecular Basis of Inheritance for the ICSE Class 12 board exam?
Learn the core ideas first, then work through the 130 practice questions on Molecular Basis of Inheritance. 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.

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