Slide 1:
Genetics and Evolution
Molecular Basis of Inheritance
In the absence of lactose
- Introduction to molecular basis of inheritance
- Link between genetics and evolution
- Role of lactose in inheritance
Slide 2:
Overview of Genetics and Evolution
- Genetics: The study of genes and heredity
- Evolution: The process by which species change and diversify over time
- The connection between genetics and evolution
Slide 3:
Molecular Basis of Inheritance
- DNA (Deoxyribonucleic acid) as the genetic material
- Importance of DNA in inheritance
- Structure of DNA (double helix)
Slide 4:
DNA Replication
- Semiconservative replication
- Role of DNA polymerase
- Enzymes involved in DNA replication
- Importance of accurate replication
Slide 5:
Transcription
- Process of transferring genetic information from DNA to RNA
- Role of RNA polymerase
- Mechanism of transcription
- Different types of RNA (mRNA, tRNA, rRNA)
Slide 6:
Genetic Code and Translation
- Genetic code: The language of nucleotides that determines the sequence of amino acids in proteins
- Codons and anti-codons
- Role of ribosomes in translation
Slide 7:
Gene Expression and Regulation
- Gene expression: The process by which information from a gene is used to synthesize a functional gene product
- Transcription factors
- Role of enhancers and promoters
- Regulation of gene expression
Slide 8:
Mutations and Genetic Variation
- Mutations: Changes in the DNA sequence
- Types of mutations (point mutations, insertions, deletions)
- Causes of mutations (chemicals, radiation, errors in DNA replication)
- Role of mutations in genetic variation and evolution
Slide 9:
Recombinant DNA and Genetic Engineering
- Recombinant DNA technology: Combining DNA from different sources
- Cloning of genes and organisms
- Applications of genetic engineering (insulin production, genetically modified crops)
Slide 10:
Inheritance of Genetic Disorders
- Autosomal and sex-linked disorders
- Pedigree analysis
- Genetic counseling
- Pre-implantation genetic diagnosis (PGD)
Slide 11:
Introduction to Gene Regulation
- Gene regulation: The control of gene expression in response to internal and external factors
- Importance of gene regulation in maintaining cellular homeostasis
- Examples of gene regulation in development, metabolism, and response to environmental stimuli
Slide 12:
Types of Gene Regulation
- Transcriptional regulation: Control of gene expression at the level of transcription
- Induction and repression of gene expression
- Transcription factors and enhancers
- Post-transcriptional regulation: Control of gene expression after transcription
- RNA splicing and alternative splicing
- RNA stability and degradation
Slide 13:
Transcriptional Regulation
- Role of transcription factors in controlling gene expression
- Activators and repressors
- Promoters and enhancers: DNA sequences that regulate transcription
- Promoters: Binding sites for RNA polymerase
- Enhancers: Enhance or suppress transcription through binding of specific transcription factors
Slide 14:
Mechanisms of Transcriptional Regulation
- Induction: Activation of gene expression in response to specific signals or stimuli
- Example: Induction of lac operon in the presence of lactose
- Repression: Inhibition of gene expression in response to specific signals or stimuli
- Example: Repression of lac operon in the absence of lactose
Slide 15:
Lac Operon: Inducible Gene Regulation
- Lac operon in E. coli: A classic example of inducible gene regulation
- Components of the lac operon:
- Structural genes: lacZ, lacY, lacA
- Operator: Binds to repressor protein
- Repressor protein: Prevents transcription in the absence of lactose
- Promoter: RNA polymerase binding site
Slide 16:
Mechanism of Lac Operon Induction
- In the absence of lactose:
- Repressor protein binds to the operator, blocking RNA polymerase access
- lac operon is not transcribed
- In the presence of lactose:
- Lactose is converted to allolactose by β-galactosidase (encoded by lacZ)
- Allolactose binds to the repressor protein, causing conformational change
- Repressor protein can no longer bind to the operator, allowing RNA polymerase to initiate transcription of lac operon
Slide 17:
Role of cAMP-CRP in Lac Operon Regulation
- cAMP-CRP (cAMP receptor protein): Enhances transcription of the lac operon
- Regulation of cAMP levels:
- High glucose levels inhibit adenylate cyclase, reducing cAMP levels
- Low glucose levels stimulate adenylate cyclase, increasing cAMP levels
- In the presence of lactose and low glucose levels, cAMP-CRP complex binds near the lac operon promoter, enhancing transcription
Slide 18:
Post-transcriptional Regulation
- Alternative splicing: Different ways of splicing primary RNA transcripts to produce different protein isoforms
- Example: Alternative splicing of the Dscam gene in Drosophila
- RNA stability and degradation: Control of gene expression by regulating the stability of mRNA molecules
- Example: microRNAs (miRNAs) that bind to mRNA and promote degradation or inhibit translation
Slide 19:
Chromatin Remodeling and Gene Regulation
- Chromatin structure: DNA wrapped around histone proteins
- Chromatin remodeling complexes: Modify chromatin structure to regulate gene expression
- Example: ATP-dependent chromatin remodelers that slide or evict nucleosomes
- DNA methylation: Addition of methyl groups to DNA that can affect gene expression
- Example: Methylation of CpG islands in gene promoters can silence gene expression
Slide 20:
Summary
- Gene regulation plays a critical role in controlling gene expression in response to internal and external factors
- Transcriptional regulation controls gene expression at the level of transcription, through induction or repression mechanisms
- Lac operon is an example of inducible gene regulation in bacteria
- Post-transcriptional regulation involves alternative splicing, RNA stability, and degradation
- Chromatin remodeling and DNA methylation also contribute to gene regulation in eukaryotes
Slide 21:
Types of Genetic Mutations
- Point mutations: Single base changes
- Silent mutations: No change in the amino acid sequence
- Missense mutations: Change in the amino acid sequence
- Nonsense mutations: Introduction of stop codons, leading to premature termination
- Frameshift mutations: Insertions or deletions that disrupt the reading frame
- Chromosomal mutations: Larger-scale changes in chromosome structure or number
- Deletions, duplications, inversions, translocations
Slide 22:
Genetic Disorders
- Autosomal dominant disorders:
- Huntington’s disease
- Marfan syndrome
- Neurofibromatosis
- Autosomal recessive disorders:
- Cystic fibrosis
- Sickle cell anemia
- Tay-Sachs disease
- X-linked disorders:
- Hemophilia
- Duchenne muscular dystrophy
- Color blindness
Slide 23:
Genetic Testing
- Methods for genetic testing:
- Polymerase chain reaction (PCR)
- DNA sequencing
- Fluorescence in situ hybridization (FISH)
- Karyotyping
- Uses of genetic testing:
- Diagnosis of genetic disorders
- Carrier screening
- Prenatal testing
- Forensic analysis
Slide 24:
Population Genetics
- Study of genetic variation within and between populations
- Hardy-Weinberg equilibrium:
- Describes the relationship between allele frequencies and genotype frequencies in a population
- Assumptions: large population, no mutation, random mating, no migration, no selection
- Genetic drift: Random changes in allele frequencies due to chance events (bottleneck effect, founder effect)
Slide 25:
Evolutionary Mechanisms
- Natural selection: Differential survival and reproduction of individuals based on their heritable traits
- Adaptive traits increase an individual’s fitness
- Directional, stabilizing, and disruptive selection
- Gene flow: Movement of genes between populations through migration
- Mutation: Source of new genetic variation
- Genetic drift: Random changes in allele frequencies
Slide 26:
Molecular Clocks
- Molecular clocks: Use of genetic mutations to estimate the time of divergence between species
- Rate of mutation: Measured by comparing DNA sequences or protein sequences
- Assumptions: Clock-like accumulation of mutations, constant mutation rate over time and across lineages
- Applications: Estimating evolutionary relationships, dating evolutionary events
Slide 27:
Speciation
- Speciation: Process by which one species splits into two or more distinct species
- Allopatric speciation: Geographical isolation leads to reproductive isolation
- Sympatric speciation: Speciation occurs without geographical isolation, often due to polyploidy or habitat differentiation
- Reproductive barriers: Prevent interbreeding between species (prezygotic and postzygotic barriers)
Slide 28:
Evolutionary Patterns
- Convergent evolution: Similar traits evolve independently in unrelated species due to similar selective pressures
- Example: Wings in birds and bats
- Divergent evolution: Related species evolve different traits due to different selective pressures
- Example: Adaptive radiation in Galapagos finches
- Coevolution: Two or more species evolve in response to each other
- Example: Predator-prey relationships, mutualistic interactions
Slide 29:
Human Evolution
- Hominin evolution: Evolutionary history of humans and our closest relatives
- Key hominin species:
- Australopithecus afarensis (Lucy)
- Homo habilis
- Homo erectus
- Neanderthals
- Recent advances in studying human evolution using DNA analysis
Slide 30:
Conclusion
- Molecular basis of inheritance provides the foundation for understanding genetics and evolution
- Gene regulation plays a critical role in controlling gene expression
- Mutations and genetic variation contribute to genetic diversity and the potential for evolutionary change
- Population genetics and speciation shape the patterns of evolution
- Human evolution is a fascinating field that continues to reveal our evolutionary history