Slide 1

• Introduction to Molecular Basis of Inheritance
• Significance of Genetic Studies
• Overview of Griffith Experiment on Rat
• Understanding the Transformation Principle
• Overview of the Lecture

Slide 2

• Gregor Mendel’s Contributions to Genetics
• Discovery of Laws of Inheritance
• Importance of DNA in Inheritance
• Overview of DNA Structure and Function
• Nucleotides and Base Pairing Rules

Slide 3

• Composition of Nucleotides
• Roles of Purines and Pyrimidines
• DNA Strand Polarity and Directionality
• Complementary Base Pairing
• Formation of DNA Double Helix

Slide 4

• DNA Replication Process
• Role of Helicase and DNA Polymerase
• Leading and Lagging DNA Strand Synthesis
• Replication Fork and Replication Origin
• Semi-conservative Nature of DNA Replication

Slide 5

• DNA Packaging and Chromosome Structure
• Organization of DNA into Chromatin
• Role of Histones and Nucleosomes
• Levels of Chromatin Packing: Solenoid, Loop, and Scaffold
• Chromosome Structure during Cell Division

Slide 6

• Griffith Experiment on Rat: Background
• Discovery of Bacterial Transformation
• Streptococcus pneumoniae as Model Organism
• Identification of Virulent and Non-virulent Strains
• Overview of Experimental Setup

Slide 7

• Griffith Experiment: Step 1 - Injection of Non-virulent Strain
• Results: Mice Survive, No Symptoms
• Control Group for Comparison
• Conclusion: Non-virulent Strain Alone is Harmless
• Significance of Control Group in Experimental Design

Slide 8

• Griffith Experiment: Step 2 - Injection of Virulent Strain
• Results: Mice Die, Symptoms Observed
• Conclusion: Virulent Strain Alone is Deadly
• Establishing Baseline Understanding

Slide 9

• Griffith Experiment: Step 3 - Heat-Killed Virulent Strain
• Results: Mice Survive, No Symptoms
• Control Group for Comparison
• Conclusion: Heat-Killed Virulent Strain is Harmless
• Understanding the Role of Heat Treatment

Slide 10

• Griffith Experiment: Step 4 - Mixture of Heat-Killed Virulent and Non-virulent Strain
• Results: Mice Die, Symptoms Observed
• Unexpected Transformation Phenomenon
• Identification of Transforming Principle
• Conclusion: Non-virulent Strain can Acquire Virulence

11.** Griffith Experiment: Step 5 - Analysis of Mice Blood**

• Extracting Blood Samples from Mice
• Observation of Bacterial Growth on Culture Medium
• Results: Bacterial Colonies Found in Mice Injected with Mixture
• Conclusion: Non-virulent Strain has Acquired Virulence

12.** Griffith Experiment: Step 6 - Heat Treatment of Mixture**

• Heat Treatment to Destroy DNA
• Injection of Heat-Treated Mixture into Mice
• Results: Mice Survive, No Symptoms
• Conclusion: DNA is the Transforming Principle
• Implications for Genetics and Inheritance

13.** Role of DNA in Inheritance**

• Transmission of Genetic Information
• Roles of Genes and Alleles
• Relationship Between DNA and Genes
• Understanding Gene Expression
• DNA as the Blueprint for Proteins

14.** Structure of DNA**

• Double Helix Model Proposed by Watson and Crick
• Antiparallel Strands and Base Pairing
• Backbone Components: Sugar and Phosphate
• Base Pairing: Adenine-Thymine and Guanine-Cytosine
• Complementary Nature of DNA Strands

15.** DNA Replication Process**

• Semi-Conservative Replication Principle
• DNA Helicase Unwinding the Double Helix
• Role of DNA Polymerase in Adding Complementary Nucleotides
• Leading and Lagging Strand Synthesis
• Formation and Function of Okazaki Fragments

16.** DNA Packing and Chromosome Structure**

• Organization of DNA into Chromatin
• Packaging of DNA by Histones and Nucleosomes
• Higher Levels of Chromatin Folding: Loops and Scaffold
• Chromosomal Structure during Interphase and Cell Division
• Relationship between Chromosomes and Genes

17.** Molecular Basis of Inheritance - Recap**

• Key Discoveries of Griffith Experiment
• Significance of DNA in Inheritance
• Structure and Function of DNA
• DNA Replication Process
• Chromosome Structure and Packaging

18.** Genetic Variation and Evolution**

• Introduction to Genetic Variation
• Sources of Genetic Variation: Mutation and Recombination
• Role of Genetic Variation in Evolutionary Processes
• Genetic Variation and Natural Selection
• Relationship between Genetic Variation and Adaptation

19.** Natural Selection and Evolution**

• Charles Darwin’s Theory of Natural Selection
• Mechanisms of Evolution: Genetic Drift, Gene Flow
• Role of Natural Selection in Shaping Populations
• Evidence for Evolution: Fossils, Comparative Anatomy, Molecular Biology
• Relationship between Genetic Variation and Evolutionary Change

20.** Modern Genetics and Evolutionary Studies**

• Advances in Molecular Genetics Techniques
• Role of DNA Sequencing and Genetic Engineering
• Phylogenetic Analysis and Evolutionary Relationships
• Genetic Basis of Speciation and Biodiversity
• Applications of Genetics in Medicine and Agriculture

21.** Examples of Genetic Variation**

• Single nucleotide polymorphisms (SNPs)
• Insertions and deletions (indels)
• Chromosomal rearrangements (inversions, translocations)
• Copy number variations (duplications, deletions)
• Gene mutations (point mutations, frameshift mutations)

22.** Impact of Genetic Variation on Phenotypes**

• Genetic variation can result in observable differences in physical traits
• Examples of genetic variation influencing phenotypes:
  • Eye color, hair color, and skin color in humans
  • Flower color in plants
  • Coat patterns in animals
  • Enzyme activity and metabolic capabilities

23.** Recombination as a Source of Genetic Variation**

• Crossing over during meiosis leads to genetic recombination
• Increases genetic diversity by shuffling genetic material between homologous chromosomes
• Generates new combinations of alleles on the same chromosome
• Facilitates the independent assortment of alleles during gamete formation

24.** Natural Selection and Genetic Variation**

• Natural selection acts on existing genetic variation within a population
• Individuals with advantageous traits are more likely to survive and reproduce
• Over time, favorable alleles become more common in the population
• Reduces genetic variation by eliminating disadvantageous alleles
• Balancing selection and heterozygote advantage maintain genetic diversity

25.** Genetic Drift and Genetic Variation**

• Genetic drift is the random change in allele frequencies due to chance events
• Has a greater impact on small populations
• Leads to a loss of genetic variation through the fixation of alleles
• Genetic bottlenecks and founder effects are examples of genetic drift
• Can result in the loss of rare alleles and an increase in genetic disorders

26.** Gene Flow and Genetic Variation**

• Gene flow is the movement of genes between populations through migration
• Introduces new genetic variation into a population
• Reduces genetic differences between populations
• Can counteract the effects of genetic drift and promote genetic diversity
• Contributes to the formation of new species through isolation and divergence

27.** Molecular Clock and Genetic Variation**

• The molecular clock hypothesis estimates the time of divergence between species
• Assumes that genetic mutations occur at a constant rate over time
• Genetic variation accumulates proportionally to the time since divergence
• Used to study evolutionary relationships and estimate evolutionary timelines
• Example: Mitochondrial DNA sequence analysis for tracing human migration patterns

28.** Role of Genetic Variation in Adaptation**

• Genetic variation provides the raw material for adaptation
• Populations with higher genetic diversity have a greater adaptive potential
• Adaptation can occur through natural selection acting on advantageous alleles
• Examples: Antibiotic resistance in bacteria, insecticide resistance in insects
• Genetic variation allows populations to respond to changing environmental conditions

29.** Genetic Variation and Human Health**

• Genetic variation contributes to human susceptibility to diseases
• Certain genetic variants increase the risk of developing certain conditions
• Examples: BRCA1 and BRCA2 mutations in hereditary breast and ovarian cancer, HLA genes in autoimmune diseases
• Genetic testing and personalized medicine rely on understanding genetic variation
• Precision medicine aims to tailor treatments based on individual genetic profiles

30.** Conclusion**

• The understanding of genetic variation is crucial in biology and evolution
• Genetic variation provides the basis for adaptation and biodiversity
• Various mechanisms contribute to genetic variation, including mutation, recombination, and gene flow
• Genetic variation can have significant impacts on phenotypes and human health
• Continued research in genetics and evolution helps unravel the complexities of life’s diversity.