Genetics and Evolution - Molecular Basis of Inheritance - Characteristics of genetic code

Slide 1

• Introduction to Genetics and Evolution
• Molecular Basis of Inheritance
• Characteristics of Genetic Code

Slide 2

• Genetics: Study of Genes, Heredity, and Variation
• Evolution: Process of cumulative change in organisms over time
• Connection between Genetics and Evolution

Slide 3

• Molecular Basis of Inheritance:
  • DNA (Deoxyribonucleic Acid) as the genetic material
  • DNA Structure: Double helix composed of nucleotides
  • DNA Replication: Process of DNA duplication

Slide 4

• Characteristics of Genetic Code:
  • Universal: Common to all organisms
  • Triplet Code: Three nucleotides (codon) encode one amino acid
  • Non-overlapping: No overlapping between codons
  • Degenerate: Multiple codons can code for the same amino acid
  • Start and Stop Codons: Initiates and terminates protein synthesis

Slide 5

• Universal Genetic Code:
  • All living organisms share the same genetic code
  • Codons code for the same amino acids in different organisms
  • Allows transfer and sharing of genetic information

Slide 6

• Triplet Code:
  • Each codon consists of three nucleotides
  • A total of 64 possible codons (4^3)
  • Encode for 20 different amino acids and signal for start/stop

Slide 7

• Non-overlapping Code:
  • Codons read sequentially without overlap
  • Each codon specifies a single amino acid
  • Ensures accuracy during translation

Slide 8

• Degenerate Code:
  • Multiple codons can code for the same amino acid
  • Redundant nature of the genetic code
  • Provides flexibility and robustness to mutations

Slide 9

• Start and Stop Codons:
  • Start Codon: AUG (Methionine)
  • Initiates protein synthesis
  • Stop Codons: UAA, UAG, UGA
  • Terminate protein synthesis

Slide 10

• Recap:

  • Genetics and Evolution are interconnected
  • DNA is the genetic material and undergoes replication
  • Characteristics of the Genetic Code:
    • Universal, Triplet Code, Non-overlapping, Degenerate
    • Start and Stop Codons control protein synthesis

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Slide 11

• Genetic Code and Protein Synthesis:

  • Genetic code is transcribed into mRNA
  • mRNA is translated into a sequence of amino acids
  • Amino acids combine to form polypeptides/proteins

• Example:

  • DNA: ATGCGCTAA
  • Transcription (mRNA): AUGCGCUAA
  • Translation (Amino Acids): Methionine, Arginine, Stop

Slide 12

• Significance of the Genetic Code:

  • Essential for the synthesis of proteins and enzymes
  • Determines the structure and function of proteins
  • Genetic variations and mutations can alter the code

• Example:

  • Sickle cell anemia caused by a mutation in the beta-globin gene
  • Single base change leads to abnormal hemoglobin protein

Slide 13

• Effects of Mutations on the Genetic Code:

  • Silent Mutations: No change in amino acid sequence
  • Missense Mutations: One amino acid is replaced by another
  • Nonsense Mutations: Premature termination of protein synthesis
  • Frameshift Mutations: Insertion or deletion of nucleotides alters the reading frame

• Examples:

  • Silent Mutation: GCU (Ala) changed to GCC (Ala)
  • Missense Mutation: GGC (Gly) changed to GAC (Asp)
  • Nonsense Mutation: UGA (Stop) changed to UGG (Trp)
  • Frameshift Mutation: CGA (Arg) changed to CGGA (Arg)

Slide 14

• Genetic Code and Evolution:

  • Mutations can lead to genetic variation
  • Variations contribute to natural selection and evolution
  • Evolution driven by changes in the genetic code over time

• Example:

  • Peppered moth: Industrial melanism and camouflage
  • Mutations in moth genes led to changes in wing coloration

Slide 15

• Regulation of Gene Expression:

  • Genetic code controls the expression of genes
  • Regulatory elements determine when and where genes are expressed
  • Transcription factors and epigenetic modifications play a role

• Example:

  • Homeobox genes regulate the development and patterning of body structures

Slide 16

• Epigenetics and Genetic Code:

  • Epigenetic modifications can alter gene expression without changing the genetic code
  • DNA methylation, histone modifications, and non-coding RNA influence gene activity
  • Epigenetic changes can be inherited and impact evolution

• Example:

  • DNA methylation can silence genes during embryonic development

Slide 17

• Genetic Code and Mutagens:

  • Mutagens are agents that induce mutations in the genetic code
  • Chemical mutagens, radiation, and certain viruses can cause mutations
  • Mutagen exposure can lead to genetic disorders and increased genetic variation

• Example:

  • UV radiation from the sun can cause damage to DNA and increase the risk of skin cancer

Slide 18

• Reprogramming the Genetic Code:

  • Genetic engineering allows modification of the genetic code
  • Recombinant DNA technology and gene editing tools like CRISPR-Cas9
  • Can be used for medical applications, agriculture, and research

• Example:

  • Insulin production using genetically modified bacteria

Slide 19

• The Human Genome Project:

  • International research effort to sequence the entire human genome
  • Completed in 2003 and provided a foundation for personalized medicine
  • Enabled the study of genetic variations and complex diseases

• Example:

  • Identification of genes associated with cancer and the development of targeted therapies

Slide 20

• Conclusion:

  • Genetic code is the foundation of life and heredity
  • It determines the formation and functioning of proteins
  • Mutations, gene expression, and evolution are all influenced by the genetic code

  ====== Slide 21:

• Importance of Genetic Code:

  • Determines the sequence of amino acids in proteins
  • Provides instructions for proteins’ structure and function
  • Influences traits, development, and overall phenotype

Slide 22:

• Impact of Genetic Code on Evolution:
  • Allows for genetic variability and adaptation
  • Genetic mutations create new variations in the genetic code
  • Adaptations increase survival and reproductive success

Slide 23:

• Proteins and Genetic Code:
  • Proteins are made up of amino acids
  • The sequence of amino acids is determined by the genetic code
  • Proteins perform various functions in cells and organisms

Slide 24:

• Gene Expression and Genetic Code:
  • Gene expression is the process by which genetic information is used to create a functional protein
  • Transcription and translation are involved in gene expression
  • Genetic code guides the sequence of amino acids during translation

Slide 25:

• Implications of Genetic Code Variations:
  • Different species may have slight variations in the genetic code
  • Some organisms have expanded or altered genetic codes
  • Genetic code variations impact protein synthesis and function

Slide 26:

• Factors Affecting Genetic Code:
  • Environmental factors can affect gene expression and genetic code
  • Epigenetic modifications can alter gene expression without changing the code
  • Mutagens and DNA damage can lead to changes in the code

Slide 27:

• Examples of Genetic Code Variations:
  • Mycoplasma, a bacterial species, has a smaller genetic code with fewer codons
  • Some codon reassignments have been observed in certain organisms
  • Stop codons can be reassigned to code for specific amino acids

Slide 28:

• Genetic Code Variations in Mitochondria and Chloroplasts:
  • Mitochondria and chloroplasts have their own genetic codes
  • These organelles have their own DNA and protein synthesis machinery
  • Their genetic codes show variations compared to the nuclear genetic code

Slide 29:

• Genetic Code and Biotechnology:
  • Understanding the genetic code is essential in biotechnology applications
  • Recombinant DNA technology relies on the genetic code
  • Gene editing techniques require knowledge of the code

Slide 30:

• Recap and Summary:
  • The genetic code is universal, triplet, non-overlapping, and degenerate
  • Start and stop codons initiate and terminate protein synthesis
  • Genetic variations, mutations, and epigenetic modifications can affect the genetic code
  • The genetic code is essential for gene expression, evolution, and biotechnology applications