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Molecular Basis of Inheritance

The document outlines the molecular basis of inheritance, detailing the discovery of nucleic acids by Friedrich Miescher and the proof of DNA as genetic material through various experiments. It explains DNA packaging in prokaryotes and eukaryotes, the processes of replication and transcription, and the characteristics of the genetic code. Additionally, it covers protein synthesis, the components of the lac operon, applications of genomics, aims of the Human Genome Project, and the process and applications of DNA fingerprinting.

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6 views4 pages

Molecular Basis of Inheritance

The document outlines the molecular basis of inheritance, detailing the discovery of nucleic acids by Friedrich Miescher and the proof of DNA as genetic material through various experiments. It explains DNA packaging in prokaryotes and eukaryotes, the processes of replication and transcription, and the characteristics of the genetic code. Additionally, it covers protein synthesis, the components of the lac operon, applications of genomics, aims of the Human Genome Project, and the process and applications of DNA fingerprinting.

Uploaded by

faikmakhzankar815
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Molecular Basis of Inheritance

1. How did Friedrich Miescher discover nucleic acid?


• He isolated a substance from pus cells (wounded soldiers’ bandages).
• Called it “nuclein” (later named DNA).

2. DNA is a genetic material. Proved by:

i. Griffith’s experiment: Mice & pneumonia bacteria, discovered transformation.


ii. Avery, McCarty, MacLeod: Proved DNA is the transforming material.
iii. Hershey-Chase experiment: Proved DNA carries genetic info using bacteriophages.

3. Packaging of DNA:
• Prokaryotes: DNA is circular, few proteins.
• Eukaryotes: DNA wraps around histone proteins → forms nucleosomes →
supercoiling.
• Draw nucleosome diagram for exam.

4. Heterochromatin vs Euchromatin:

Feature Heterochromatin Euchromatin


Structure Tightly packedLoosely packed
Activity Inactive Active in transcription
Staining Dark Light

5. What is replication?
• Copying of DNA to make identical DNA before cell division.

6. Two functions of DNA:


1. Self-replication.
2. Protein synthesis (by coding for enzymes & other proteins).

7. Semi-conservative replication:
• One old strand, one new strand in daughter DNA.
• Meselson & Stahl’s experiment proved it with nitrogen isotopes.

8. Define:
• Central Dogma: DNA → RNA → Protein.
• Transcriptional unit: Stretch of DNA transcribed to RNA.
• Genetic code: Sequence of bases coding for amino acids.
• Frame shift mutation: Addition/deletion of bases shifts reading frame.
• Point mutation: Single base change.
• UTR: Untranslated region (before start & after stop codon).

9. Transcription Process:
• DNA forms mRNA by RNA polymerase.
• Occurs in nucleus.
• mRNA carries message to ribosome.

10. Types of RNA in eukaryotes:


1. mRNA: Carries code.
2. tRNA: Transfers amino acids.
3. rRNA: Forms ribosomes.

11. hnRNA processing:


• hnRNA (pre-mRNA) gets:
• Capping (5’ end).
• Tailing (poly-A tail at 3’ end).
• Splicing (removal of introns).

12. Characteristics of Genetic Code:


• Universal.
• Triplet codon.
• Degenerate (multiple codons for same amino acid).
• Non-overlapping.
• Continuous.

13. Protein synthesis (Translation):


• mRNA → protein.
• Steps: Initiation → Elongation → Termination.

14. Requirements for Translation:


• mRNA, tRNA, ribosomes, amino acids, enzymes, ATP & GTP energy.

15. Operon Enzymes:


• Produced by structural genes.
• Example: Lac operon enzymes break lactose.
• Functions: metabolism, energy production.
⸻

16. Components of Lac Operon:


• Regulator gene.
• Promoter.
• Operator.
• Structural genes (Z, Y, A).

17. Applications of Genomics:


• Disease diagnosis.
• Personalized medicine.
• Gene therapy.
• Evolution studies.

18. Aims of Human Genome Project (HGP):


• Map all human genes.
• Study gene functions.
• Detect mutations.
• Help in medical research.

19. DNA Fingerprinting:


• Steps: DNA extraction → Cutting by enzymes → Gel electrophoresis →
Blotting → Probing.
• Applications: Criminal cases, paternity tests, biodiversity studies.

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