Genetics And Evolution- Molecular Basis Of Inheritance - In Absence Of Tryptophan

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.