Slide 1: Genetics and Evolution- Molecular Basis of Inheritance - In Absence of Tryptophan

• Genetic information is stored in the form of DNA.
• DNA undergoes replication, transcription, and translation to produce proteins.
• In the absence of tryptophan, certain gene regulatory mechanisms operate.

Slide 2: Gene Regulatory Mechanisms

• Operon concept proposed by Jacob and Monod.
• Genes organized into operons in prokaryotes.
• Lac operon is an example of an inducible operon.
• Tryptophan operon is an example of a repressible operon.
• Operons consist of structural genes, operator region, and promoter region.

Slide 3: Lac Operon

• Lac operon controls the metabolism of lactose in E. coli bacteria.
• Composed of three genes: lacZ, lacY, and lacA.
• lacZ encodes β-galactosidase, lacY encodes lactose permease, and lacA encodes transacetylase.
• In the presence of lactose, lac operon is induced.

Slide 4: Inducer and Repressor in Lac Operon

• Inducer: Lactose acts as an inducer by binding to the repressor protein.
• Repressor protein: Binds to the operator region and inhibits RNA polymerase from transcribing the structural genes.
• In the presence of lactose, repressor is inactivated by binding to lactose.

Slide 5: Tryptophan Operon

• Regulates the synthesis of tryptophan in E. coli bacteria.
• Consists of five structural genes: trpE, trpD, trpC, trpB, and trpA.
• In the presence of tryptophan, tryptophan operon is repressed.

Slide 6: Tryptophan Operon Regulation

• Repressor protein: Binds to the operator region and inhibits RNA polymerase from transcribing the structural genes.
• In the presence of tryptophan, tryptophan binds to the repressor protein and activates it.
• Activated repressor binds to the operator region, blocking transcription of the structural genes.

Slide 7: Examples of Gene Regulatory Mechanisms

• Positive control: Activator proteins bind to enhancer regions, enhancing gene expression.
• Negative control: Repressor proteins bind to operator regions, inhibiting gene expression.

Slide 8: Gene Expression in Eukaryotes

• Eukaryotes have more complex gene regulatory mechanisms.
• Chromatin structure and DNA packaging affect gene expression.
• Transcription factors and enhancers regulate gene expression.
• Epigenetic modifications can also influence gene expression.

Slide 9: Transcription Factors

• Bind to specific DNA sequences called promoter or enhancer regions.
• Activate or repress RNA polymerase binding to the promoter region.
• Play a crucial role in regulating gene expression in eukaryotes.

Slide 10: Epigenetics and Gene Expression

• Epigenetic modifications influence gene expression without altering the DNA sequence.
• DNA methylation and histone modification are examples of epigenetic changes.
• Abnormal epigenetic regulation can lead to various diseases.
• Understanding epigenetic mechanisms is essential in studying gene expression.

Slide 11: DNA Replication

• Process by which DNA is copied to produce two identical DNA molecules.
• Enzymes involved: DNA helicase, DNA polymerase, DNA ligase.
• Occurs in the S phase of the cell cycle.
• Semiconservative replication - each new DNA molecule consists of one strand from the original DNA molecule and one newly synthesized strand.

Slide 12: Transcription

• Process by which DNA is used as a template to synthesize RNA.
• RNA polymerase binds to the promoter region and separates the DNA strands.
• RNA polymerase adds complementary RNA nucleotides.
• Transcription stops at the termination region.
• Three types of RNA are formed: mRNA, tRNA, and rRNA.

Slide 13: Genetic Code

• Genetic code is a set of rules that determines how amino acids are encoded in a DNA sequence.
• It is a triplet code, with each codon consisting of three nucleotides.
• There are 64 possible codons, including start and stop codons.
• Some codons code for the same amino acid (redundancy).
• Example: AUG codes for methionine, UAA, UAG, and UGA are stop codons.

Slide 14: Translation

• Process by which the mRNA sequence is converted into a polypeptide chain.
• Occurs in the ribosomes.
• tRNA carries specific amino acids to the ribosome.
• tRNA anticodon pairs with the mRNA codon.
• Peptide bonds form between amino acids, resulting in a protein.

Slide 15: Gene Mutations

• Mutations are changes in the DNA sequence.
• Types of mutations: point mutations, frameshift mutations.
• Point mutations include substitutions, insertions, and deletions.
• Frameshift mutations occur due to insertions or deletions, resulting in a reading frame shift.

Slide 16: Genetic Disorders

• Genetic disorders are caused by mutations in genes.
• Examples: Down syndrome, cystic fibrosis, sickle cell anemia.
• Some genetic disorders are inherited, while others occur spontaneously.
• Genetic counseling and testing help diagnose and manage genetic disorders.

Slide 17: Molecular Basis of Evolution

• Evolution is driven by changes in the genetic material of populations.
• Mutations introduce genetic variability.
• Natural selection acts on genetic variation, leading to adaptation and speciation.
• Genetic drift and gene flow also influence the genetic makeup of populations.

Slide 18: Hardy-Weinberg Principle

• Describes the genetic equilibrium in a population.
• Allele frequencies remain constant from generation to generation in the absence of evolutionary forces.
• Five key assumptions: large population size, random mating, no mutation, no migration/gene flow, no natural selection.

Slide 19: Mechanisms of Microevolution

• Microevolution refers to the small-scale changes in allele frequencies within a population.
• Four mechanisms of microevolution: natural selection, genetic drift, gene flow, mutation.
• Natural selection results in the adaptation of populations to their environment.
• Genetic drift is a random change in allele frequencies due to sampling effects.
• Gene flow occurs when individuals migrate and introduce new genes to a population.

Slide 20: Speciation

• Speciation is the process by which new species arise.
• Two main types: allopatric speciation and sympatric speciation.
• Allopatric speciation occurs when populations are geographically separated.
• Sympatric speciation occurs when populations diverge without geographic isolation.

Slide 21: Genome and Genomics

• Genome refers to the complete set of DNA or genetic material in an organism.
• Genomics is the study of the structure, function, and evolution of genomes.
• Genomics involves analyzing DNA sequences, identifying genes, and studying their interactions.
• The Human Genome Project was a landmark genomics project that sequenced the human genome.
• Genomics has applications in medicine, agriculture, and evolutionary biology.

Slide 22: Recombinant DNA Technology

• Recombinant DNA technology involves combining DNA from different sources to create novel genetic combinations.
• Techniques used in recombinant DNA technology: restriction enzymes, DNA ligase, polymerase chain reaction (PCR), cloning vectors.
• Applications of recombinant DNA technology: production of recombinant proteins, genetic engineering of crops, gene therapy.

Slide 23: Polymerase Chain Reaction (PCR)

• PCR is a technique used to amplify a specific DNA sequence.
• Steps of PCR: denaturation, annealing, extension.
• PCR requires a DNA template, primers, DNA polymerase, and nucleotides.
• Applications of PCR: DNA fingerprinting, diagnosis of genetic diseases, forensic analysis.

Slide 24: Transgenic Organisms

• Transgenic organisms contain foreign genes that have been artificially introduced into their genome.
• Transgenic organisms are often created for research, agriculture, or medical purposes.
• Examples of transgenic organisms include genetically modified crops, transgenic mice, and insulin-producing bacteria.
• Ethical considerations surrounding the use of transgenic organisms exist.

Slide 25: Gene Therapy

• Gene therapy is an experimental approach to treat genetic diseases.
• In gene therapy, a functional copy of a gene is introduced into the patient’s cells to correct the genetic defect.
• Gene therapy can be performed ex vivo (outside the body) or in vivo (inside the body).
• Challenges in gene therapy include gene delivery, immunogenicity, and long-term effectiveness.

Slide 26: Mitosis

• Mitosis is a process of cell division that results in the formation of two identical daughter cells.
• Steps of mitosis: prophase, metaphase, anaphase, telophase.
• Mitosis is essential for growth, tissue repair, and asexual reproduction.
• Mitosis ensures that each daughter cell receives a complete set of chromosomes.

Slide 27: Meiosis

• Meiosis is a specialized form of cell division that results in the formation of haploid gametes.
• Steps of meiosis: meiosis I (reduction division) and meiosis II (equational division).
• Meiosis introduces genetic variation through crossing over and independent assortment of chromosomes.
• Meiosis is crucial for sexual reproduction and contributes to genetic diversity.

Slide 28: Mendelian Genetics

• Mendelian genetics refers to the principles of inheritance proposed by Gregor Mendel.
• Mendel’s laws include the Law of Segregation and the Law of Independent Assortment.
• Law of Segregation states that alleles segregate during gamete formation and are randomly recombined during fertilization.
• Law of Independent Assortment states that alleles of different genes segregate independently during gamete formation.

Slide 29: Punnett Square

• Punnett square is a diagram used to predict the outcomes of a cross between two individuals.
• Alleles for each gene are represented along the sides of the square.
• The possible combinations of alleles in the offspring are displayed within the squares.
• Punnett squares help determine the genotypes and phenotypes of offspring.

Slide 30: Hardy-Weinberg Equilibrium

• Hardy-Weinberg equilibrium describes the genetic equilibrium in a population under certain conditions.
• The equation p^2 + 2pq + q^2 = 1 represents the genotype frequencies in a population.
• p and q represent the allele frequencies for a particular gene.
• Hardy-Weinberg equilibrium can be used to estimate and analyze genetic variation in populations.