Slide 1

  • Topic: Genetics and Evolution - Molecular Basis of Inheritance - Meaning
  • Key Concepts:
    • Molecular basis of inheritance
    • Transmission of genetic information
    • DNA and RNA
    • Genetic code and gene expression

Slide 2

  • Molecular Basis of Inheritance
    • It refers to the mechanisms by which genetic information is passed from one generation to the next.
    • The study of the molecular basis of inheritance focuses on understanding the structure, function, and replication of DNA, as well as gene expression.

Slide 3

  • DNA (Deoxyribonucleic Acid)
    • Double-stranded molecule composed of nucleotides.
    • Nucleotides consist of a sugar (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine).
    • DNA carries the genetic information for all organisms.

Slide 4

  • RNA (Ribonucleic Acid)
    • Single-stranded molecule composed of nucleotides.
    • Nucleotides consist of a sugar (ribose), a phosphate group, and a nitrogenous base (adenine, uracil, cytosine, or guanine).
    • RNA plays a crucial role in gene expression and protein synthesis.

Slide 5

  • Genetic Code
    • The genetic code is a set of rules that determine how the nucleotide sequence of a gene is translated into a specific amino acid sequence during protein synthesis.
    • It consists of codons, which are specific sequences of three nucleotides that represent a particular amino acid or a stop signal.

Slide 6

  • Gene Expression
    • Gene expression refers to the process by which the information encoded in a gene is used to synthesize a functional gene product, such as a protein.
    • It involves transcription (DNA to RNA) and translation (RNA to protein).
    • Gene expression is regulated by various factors, including transcription factors and environmental signals.

Slide 7

  • Transcription
    • Transcription is the first step of gene expression.
    • It involves the synthesis of RNA from a DNA template.
    • RNA polymerase catalyzes the transcription process by binding to the DNA and assembling the corresponding RNA molecule.
    • The resulting RNA molecule is called messenger RNA (mRNA).

Slide 8

  • Translation
    • Translation is the second step of gene expression.
    • It involves the synthesis of a protein from an mRNA template.
    • Ribosomes play a crucial role by decoding the mRNA sequence and assembling the correct sequence of amino acids to form a protein.

Slide 9

  • Examples of Molecular Basis of Inheritance
    • DNA replication: Ensuring accurate transmission of genetic information during cell division.
    • Mutations: Changes in the DNA sequence that can lead to genetic variation and evolution.
    • Genetic disorders: Inherited diseases caused by mutations in specific genes.

Slide 10

  • Implications of Molecular Basis of Inheritance
    • Understanding the molecular basis of inheritance has significant implications in various fields, including medicine, agriculture, and forensic science.
    • It allows for the development of genetic tests, gene therapies, genetically modified organisms (GMOs), and identification of individuals through DNA profiling.

Slide 11

  • Structure of DNA
    • Double helix structure with two antiparallel strands.
    • Complementary base pairing: A-T and G-C.
    • The sugar-phosphate backbone provides stability and protection for the nucleotide sequence.

Slide 12

  • Replication of DNA
    • Semi-conservative process where each parent strand serves as a template for the synthesis of a new complementary strand.
    • Involves enzymes such as DNA helicase, DNA polymerase, and DNA ligase.
    • Ensures accurate transmission of genetic information during cell division.

Slide 13

  • Mutations
    • Changes in the DNA sequence due to errors during replication or exposure to mutagens.
    • Types of mutations: substitution, deletion, insertion, inversion, and duplication.
    • Mutations can be spontaneous or induced.
    • Can lead to genetic variation and evolution.

Slide 14

  • Genetic Disorders
    • Inherited diseases caused by mutations in specific genes.
    • Examples: cystic fibrosis, sickle cell anemia, Huntington’s disease.
    • Genetic counseling and testing can help individuals and families manage and understand genetic disorders.

Slide 15

  • RNA Processing
    • Pre-mRNA undergoes modifications before being translated into a protein.
    • Introns (non-coding regions) are removed through splicing to form mature mRNA.
    • Exons (coding regions) are joined together.
    • Addition of a 5’ cap and a poly(A) tail enhances stability and transport of mRNA.

Slide 16

  • Types of RNA
    • Messenger RNA (mRNA): carries the genetic information from DNA to the ribosomes for protein synthesis.
    • Transfer RNA (tRNA): brings specific amino acids to the ribosomes during translation.
    • Ribosomal RNA (rRNA): forms the ribosomes, the site of protein synthesis.

Slide 17

  • Genetic Code Examples
    • Start codon: AUG (codes for methionine).
    • Stop codons: UAA, UAG, UGA (signal the end of translation).
    • Example of a codon: UUU (codes for the amino acid phenylalanine).

Slide 18

  • Gene Regulation
    • Gene expression can be regulated at various levels to control protein synthesis.
    • Transcription factors bind to specific DNA sequences and either enhance or repress gene expression.
    • Environmental signals can also influence gene expression.

Slide 19

  • Epigenetics
    • Study of heritable changes in gene function that do not involve changes in the DNA sequence.
    • Molecular modifications such as DNA methylation and histone acetylation can affect gene expression.
    • Can be influenced by environmental factors and have implications in disease development.

Slide 20

  • Genetic Engineering
    • Manipulation of genetic material to modify organisms for specific purposes.
    • Recombinant DNA technology allows the transfer of genes between different organisms.
    • Application examples: production of insulin using recombinant bacteria, genetically modified crops with increased resistance to pests.

/********************************************************/

Slide 21

  • Regulation of Gene Expression
    • Gene expression can be regulated at multiple levels, including transcription, translation, and post-translational modifications.
    • Transcriptional regulation: control of gene expression through the binding of transcription factors to specific regulatory regions of DNA.
    • Post-transcriptional regulation: processing of pre-mRNA, alternative splicing, and stability of mRNA.
    • Translational regulation: control of protein synthesis through regulatory molecules that interact with mRNA or ribosomes.
    • Post-translational modifications: addition of chemical groups to proteins that can alter their structure and function.

Slide 22

  • Genetic Disorders and Inheritance Patterns
    • Genetic disorders can be inherited in various patterns:
      • Autosomal dominant: a single copy of the mutated gene is sufficient to cause the disorder.
      • Autosomal recessive: both copies of the gene must be mutated to manifest the disorder.
      • X-linked dominant: a mutated gene on the X chromosome causes the disorder, and it can affect both males and females.
      • X-linked recessive: a mutated gene on the X chromosome causes the disorder, and it primarily affects males.
      • Y-linked: a mutation on the Y chromosome can be passed only from father to son.

Slide 23

  • DNA Profiling
    • DNA profiling, also known as DNA fingerprinting, is a technique used to identify individuals based on their unique DNA profiles.
    • It relies on the analysis of specific regions of the genome, such as short tandem repeats (STRs) or variable number tandem repeats (VNTRs).
    • DNA profiling is commonly used in forensic science, paternity testing, and identification of human remains.

Slide 24

  • Cloning
    • Cloning refers to the process of creating genetically identical organisms or replicates DNA fragments.
    • Types of cloning: recombinant DNA cloning, reproductive cloning, and therapeutic cloning.
    • Recombinant DNA cloning involves the insertion of a DNA fragment into a vector for replication and further study.
    • Reproductive cloning aims to create an entire organism with the same genetic material as the donor.
    • Therapeutic cloning focuses on creating cells or tissues for medical purposes, such as regenerative medicine.

Slide 25

  • Transgenic Organisms
    • Transgenic organisms are organisms that have had foreign genes introduced into their genome using recombinant DNA technology.
    • Transgenic organisms can be plants, animals, or microorganisms.
    • Applications of transgenic organisms include the production of therapeutic proteins, development of disease-resistant crops, and studies in basic research.

Slide 26

  • Evolution
    • Evolution is the process of gradual change in the inherited characteristics of biological populations over successive generations.
    • The driving force of evolution is natural selection, where individuals with beneficial traits have better reproductive success.
    • Other mechanisms of evolution include genetic drift, gene flow, and mutation.
    • Evolutionary theory provides a foundation for understanding the diversity of life forms and their relationships.

Slide 27

  • Hardy-Weinberg Principle
    • The Hardy-Weinberg principle describes the relationship between the frequencies of alleles in a population and the genotype frequencies.
    • It states that allelic frequencies remain constant across generations in the absence of evolutionary forces.
    • The equation p2 + 2pq + q2 = 1 represents the genotypic frequencies of a population in Hardy-Weinberg equilibrium.
    • It is used as a null model for studying evolutionary processes.

Slide 28

  • Evidence for Evolution
    • Fossil records: preserved remains or traces of ancient organisms provide evidence for evolutionary changes over time.
    • Comparative anatomy: similarities in the structure of different organisms suggest common ancestry.
    • Comparative embryology: similarities in the early development of different organisms reveal shared evolutionary history.
    • Molecular biology: comparing DNA and protein sequences provides insights into the relatedness of species.

Slide 29

  • Speciation
    • Speciation is the process by which new species arise from existing ones.
    • It can occur through allopatric speciation (geographical isolation), sympatric speciation (reproductive isolation within the same geographic area), or parapatric speciation (partial isolation).
    • Speciation can be driven by factors such as natural selection, genetic drift, and gene flow.

Slide 30

  • Human Evolution
    • The study of human evolution aims to understand the origins and development of Homo sapiens.
    • Fossil evidence suggests a gradual evolution from ancestral hominins to modern humans.
    • Major milestones in human evolution include bipedalism, increased intelligence, tool use, and cultural advancements.
    • Genetic studies have provided insights into human migration patterns and genetic variations among different populations. /********************************************************/