Molecular Basis of Inheritance Lecture Notes

Jul 24, 2024

Molecular Basis of Inheritance Lecture Notes

Introduction

  • Chapter: Molecular Basis of Inheritance
  • Importance: Key chapter with 8-10 questions frequently asked in exams (e.g., 9 questions in 2022).

Key Concepts and Definitions

  • Inheritance: Transmission of characters from one generation to another.
  • Gene: Fundamental unit of heredity.
  • DNA (Deoxyribonucleic Acid): Genetic material in most organisms; composed of nucleotides.

Structure of DNA

  • Base Structure: Two strands of nucleotides forming a double helix.
  • Nucleotide Composition: Comprised of a phosphate group, a sugar (deoxyribose), and nitrogenous bases (A, T, C, G).
  • Double Helix: The two strands run in opposite directions (anti-parallel).

Principal Functions of DNA

  1. Replication: DNA can copy itself for cell division.
  2. Transcription: DNA is transcribed to mRNA.
  3. Translation: mRNA is translated to protein.

Types of RNA

  • mRNA (Messenger RNA): Carries genetic information from DNA to ribosomes.
  • tRNA (Transfer RNA): Brings amino acids to ribosomes during protein synthesis.
  • rRNA (Ribosomal RNA): Combines with proteins to form ribosomes.

Genetic Information Flow

  • Central Dogma of Molecular Biology:
    • DNA → RNA → Protein
    • Reverse transcription can occur (RNA → DNA in retroviruses).

DNA Replication

  • Semi-Conservative Model: Each daughter DNA molecule contains one original and one new strand.
  • DNA Polymerase: Involved in synthesizing new DNA strands.

Steps of DNA Replication

  1. Initiation: Enzymes unwind the DNA helix.
  2. Elongation: New nucleotides are added complementary to the template strand.
  3. Termination: Replication ends at specific sequences.

Mendelian Principles (Review Relevant Content)

  • Dominance, Segregation, and Independent Assortment.

Mutations and Genetic Variation

  • Types of Mutations: Point mutations, insertions, deletions.
  • Effects of Mutations: Can lead to changes in amino acid sequences, possibly resulting in functional changes of proteins.

Human Genome Project

  • Goal: To map all the genes in the human genome.
  • Objective: Identify genetic disorders, understand genetic makeup, and improve medicine.
  • Outcome: Estimated 20,000-25,000 genes identified.

DNA Fingerprinting

  • Technique: Analyze repeated sequences in non-coding regions of DNA.
  • Applications: Forensic science, paternity testing, genetic diversity studies.

Techniques in Molecular Biology

  1. PCR (Polymerase Chain Reaction): Amplification of specific DNA sequences.
  2. Gel Electrophoresis: Separating DNA fragments based on size.
  3. Southern Blotting: Transfer and detection of DNA from the gel to a membrane.

Summary

  • Understanding molecular and genetic processes is essential for biotechnology, medicine, and biology.
  • The structure and function of DNA, RNA, and proteins underpin all biological systems.
  • Human Genome Project and its implications for health science.
  • Key Terms:
    • DNA, RNA, Nucleotide, Codon, Gene, Mutation, Genome
  • Important Figures: Watson and Crick (DNA structure), Frederick Griffith (Transformation Principle), Hershey and Chase (DNA as genetic material).
  • Reference: NCERT Biology Textbook, Chapter: Molecular Basis of Inheritance.

Final Notes

  • Stay updated on essential topics and concepts for successful examination preparation!