Chapter 5: Molecular Basis of Inheritance
वंशागति के आणविक आधार
- Structure of DNA & Packaging
- Replication, Transcription, Translation
- Genetic Code & Mutations
- Gene Regulation (Lac Operon)
- Human Genome Project & DNA Fingerprinting
1. The DNA (डीएनए)
DNA is a long polymer of deoxyribonucleotides. The double helix model was proposed by Watson and Crick in 1953.
Structure of Polynucleotide Chain
A nucleotide has three components:
- Nitrogenous Base: Purines (Adenine, Guanine) and Pyrimidines (Cytosine, Thymine).
- Pentose Sugar: Deoxyribose in DNA.
- Phosphate Group: Linked to 5'-OH of nucleoside.
Packaging of DNA Helix
In eukaryotes, the DNA is wrapped around a positively charged histone octamer to form a structure called the Nucleosome.
2. The Search for Genetic Material
Several experiments proved that DNA is the genetic material. The most unequivocal proof came from the experiments of Hershey and Chase (1952).
3. Replication (प्रतिकृति)
Watson and Crick proposed the Semi-conservative scheme for replication. The replication fork is the Y-shaped structure where new DNA is synthesized.
4. Transcription (अनुलेखन)
Copying genetic info from DNA to RNA. A transcription unit has 3 regions.
5. Translation & Genetic Code
Translation occurs in ribosomes where tRNA brings amino acids based on mRNA codons.
6. Regulation of Gene Expression (Lac Operon)
In E. coli, the Lac Operon controls lactose metabolism. It consists of regulatory and structural genes.
7. DNA Fingerprinting
Technique to identify individuals based on VNTRs. Developed by Alec Jeffreys.
📚 Revise Previous Units (Mission 100)
Strengthen your Biology foundation by revisiting these key chapters:
© 2026 NCERTClasses.com | Mission 100 Board Exam
Prepared strictly as per NCERT Rationalised Syllabus
No comments:
Post a Comment