Molecular Basis of Inheritance

  • Genetics and Evolution
  • Importance of understanding the molecular basis of inheritance
  • Significance of radioactive Phosphorus and Sulfur in experiments

DNA and RNA

  • DNA (Deoxyribonucleic acid)

    • Structure: double helix composed of nucleotides
    • Function: carries genetic information
    • Examples: chromosomes, genes

  • RNA (Ribonucleic acid)

    • Structure: single-stranded nucleic acid molecule
    • Types of RNA: mRNA, tRNA, rRNA
    • Function: participates in protein synthesis

Nucleotides

  • Composition of nucleotides:

    • Nitrogenous base (Adenine, Thymine, Cytosine, Guanine, Uracil)
    • Pentose sugar (deoxyribose in DNA, ribose in RNA)
    • Phosphate group

  • Examples:

    • Adenine pairs with Thymine in DNA
    • Guanine pairs with Cytosine in DNA

DNA Replication

  • Process by which DNA is copied during cell division
  • Steps:
    1. DNA unwinding
    2. Separation of DNA strands
    3. Complementary base pairing
    4. Formation of new DNA strands
  • Example: Watson and Crick model of DNA replication

Transcription

  • Process of synthesizing RNA using DNA as a template
  • Steps:
    1. Initiation
    2. Elongation
    3. Termination
  • Example: mRNA synthesis from DNA template

Genetic Code

  • Set of rules by which information in genetic material (DNA or mRNA) is translated into proteins
  • Triplet code: each codon consists of three nucleotides
  • Examples:
    • AUG: start codon
    • UAA, UAG, UGA: stop codons

Translation

  • Process of protein synthesis using the genetic code
  • Steps:
    1. Initiation
    2. Elongation
    3. Termination
  • Examples: tRNA, ribosomes

Mutations

  • Changes in DNA sequence
  • Types of mutations:
    1. Point mutations (substitution, insertion, deletion)
    2. Frameshift mutations
    3. Chromosomal mutations (deletion, duplication, inversion, translocation)
  • Examples: sickle cell anemia, Down syndrome

Recombinant DNA Technology

  • Techniques used to manipulate DNA for various purposes
  • Methods:
    1. Restriction enzymes
    2. Gel electrophoresis
    3. Polymerase Chain Reaction (PCR)
    4. DNA sequencing
  • Examples: production of insulin, genetically modified organisms

Gene Expression

  • Process by which genes are converted into functional proteins

  • Regulation of gene expression:

    • Transcription factors
    • DNA methylation
    • Histone modification

  • Example: differentiation of cells

Regulation of Gene Expression

  • Importance of regulating gene expression
  • Types of gene regulation:
    1. Transcriptional regulation
    2. Post-transcriptional regulation
    3. Translational regulation
    4. Post-translational regulation
  • Example: lac operon in E. coli

Transcriptional Regulation

  • Control of gene expression at the transcriptional level
  • Mechanisms of transcriptional regulation:
    1. Promoter regions and transcription factors
    2. Enhancers and silencers
    3. Chromatin remodeling
    4. DNA methylation
  • Examples: homeobox genes, tumor suppressor genes

Post-Transcriptional Regulation

  • Regulation of gene expression after transcription has occurred
  • Mechanisms of post-transcriptional regulation:
    1. mRNA processing (splicing, polyadenylation)
    2. mRNA stability
    3. RNA interference
  • Examples: alternative splicing, microRNAs

Translational Regulation

  • Control of gene expression at the level of translation
  • Mechanisms of translational regulation:
    1. Translational repressors and activators
    2. Ribosome binding sites
    3. RNA secondary structures
  • Examples: iron response element (IRE), translational control in oocytes

Post-Translational Regulation

  • Regulation of gene expression after translation has occurred
  • Mechanisms of post-translational regulation:
    1. Protein folding and modification
    2. Protein degradation
    3. Protein-protein interactions
    4. Signal transduction pathways
  • Examples: phosphorylation, ubiquitination

Epigenetics

  • Study of heritable changes in gene expression without changes in DNA sequence
  • Mechanisms of epigenetic regulation:
    1. DNA methylation
    2. Histone modification
    3. Non-coding RNAs
  • Examples: genomic imprinting, X chromosome inactivation

Evolutionary Significance

  • Role of molecular basis of inheritance in evolution
  • Molecular evidence for evolution:
    1. Comparative genomics
    2. Phylogenetics
    3. Molecular clocks
  • Example: homologous genes

Genetic Disorders

  • Diseases caused by genetic mutations or abnormalities
  • Types of genetic disorders:
    1. Single gene disorders (e.g., cystic fibrosis, Huntington’s disease)
    2. Chromosomal disorders (e.g., Down syndrome, Turner syndrome)
    3. Multifactorial disorders (e.g., diabetes, heart disease)
  • Examples: sickle cell anemia, hemophilia

Genetic Engineering

  • Manipulation of genes for practical purposes
  • Applications of genetic engineering:
    1. Agriculture (crop improvement, pest resistance)
    2. Medicine (gene therapy, production of therapeutic proteins)
    3. Forensics (DNA profiling)
    4. Biotechnology (production of enzymes, biofuels)
  • Examples: Golden Rice, genetically engineered insulin

Ethical Considerations

  • Moral and societal implications of genetic research and technologies
  • Ethical issues in genetics:
    1. Privacy and confidentiality
    2. Genetic discrimination
    3. Designer babies
    4. Patenting of genes
  • Examples: genetic testing, cloning

Inheritance Patterns

  • Mendelian inheritance
    • Law of segregation
    • Law of independent assortment
  • Non-Mendelian inheritance
    • Incomplete dominance
    • Codominance
    • Multiple alleles
    • Polygenic traits
  • Examples: Mendel’s pea plant experiments, blood type inheritance

Genetic Variation

  • Sources of genetic variation
    • Mutation
    • Genetic recombination
    • Sexual reproduction
  • Importance of genetic variation
    • Adaptation to changing environments
    • Evolutionary potential
  • Examples: DNA mutations, crossing over during meiosis

Human Genome Project

  • International research project
  • Aims:
    • Determine the complete sequence of the human genome
    • Identify genes and their function
    • Understand the genetic basis of diseases
  • Impact of the Human Genome Project
    • Advances in personalized medicine
    • Development of gene therapies
  • Examples: mapping of human chromosomes, identification of disease-related genes

Cloning

  • Process of producing genetically identical copies
  • Types of cloning:
    • Reproductive cloning
    • Therapeutic cloning
  • Applications of cloning:
    • Agriculture (cloning of livestock)
    • Medicine (production of organs for transplantation)
  • Example: Dolly the sheep

Stem Cells

  • Undifferentiated cells with the potential to develop into different cell types
  • Types of stem cells:
    • Totipotent
    • Pluripotent
    • Multipotent
  • Applications of stem cells:
    • Regenerative medicine
    • Drug development
  • Example: use of embryonic stem cells in research

Biotechnology

  • Application of biological knowledge and techniques to develop products and processes
  • Areas of biotechnology:
    • Medical biotechnology
    • Agricultural biotechnology
    • Environmental biotechnology
  • Examples: production of recombinant proteins, genetic engineering of crops

Genetically Modified Organisms (GMOs)

  • Organisms whose genetic material has been altered using genetic engineering techniques
  • Examples of GMOs:
    • Genetically modified crops with enhanced traits (e.g., insect resistance, herbicide tolerance)
    • Genetically modified animals for medical research
  • Benefits and concerns of GMOs:
    • Increased crop yield and productivity
    • Environmental and health concerns

RNA Interference (RNAi)

  • Natural process of gene silencing in cells
  • Mechanism of RNA interference:
    • Introduction of small RNA molecules to target specific mRNA molecules for degradation
    • Regulation of gene expression
  • Applications of RNAi:
    • Functional genomics
    • Therapeutics
  • Example: use of RNAi in cancer research

Genetic Testing

  • Analysis of DNA or proteins to identify genetic disorders or individual traits
  • Types of genetic testing:
    • Diagnostic testing
    • Carrier testing
    • Predictive testing
  • Uses and limitations of genetic testing:
    • Disease diagnosis and risk assessment
    • Ethical and privacy concerns
  • Example: testing for inherited cancer susceptibility genes

Genetic Counseling

  • Process of providing information and support to individuals and families about genetic disorders
  • Goals of genetic counseling:
    • Discussing the risk of inherited disorders
    • Assisting decision-making regarding testing and treatment options
    • Providing emotional support
  • Examples: genetic counseling for prenatal screening, family history evaluation