Title: Genetics and Evolution - Molecular Basis of Inheritance - Griffith Experiment on Rat
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.