Human Genetics Notes

  • Why Study Genetics?

    • Genetic testing available for newborns in Australia (e.g. Phenylketonuria, Cystic fibrosis).
    • Genetic variations can provide insights beyond specific conditions.

  • Nature and Nurture Interaction:

    • Environment: Represents all non-genetic factors affecting traits.
    • Genotype (genes) and Phenotype (traits):
    • Phenotype equation: Phenotype = Genotype (G) + Environment (E).

  • Definition of Genetics:

    • Study of genes, genomes, and their variations.
    • Includes understanding of the Human Genome Project.
    • The human genome consists of approximately 3 billion base pairs.

  • Lecture Themes in Genetics:

    • Structure and Function: Genomes, chromosomes, DNA, genes, transcription, and translation.
    • Replication: Mitosis and mutations.
    • Reproduction: Meiosis and chromosome variations.
    • Laws of Inheritance: Focus on monogenic disorders and family pedigrees.
    • Genetic Variation: Patterns of global diversity reflecting evolutionary history.
    • Genes and Society: Personalised medicine and gene editing implications.

  • Genomic Architecture:

    • Human cells have ~23 pairs of chromosomes (diploid), around 3 billion base pairs in total.
    • DNA in chromosomes is compacted and forms a double helix structure, with nucleosomes wrapped around histones for organization.

  • DNA Structure:

    • Consists of a sugar-phosphate backbone paired with nitrogenous bases (A, T, C, G).
    • Base pairs: A-T and G-C pairs connected through hydrogen bonds.

  • Central Dogma of Molecular Biology:

    1. Transcription: Information from DNA gets copied into mRNA.
    2. Translation: mRNA is translated into proteins.
    3. Transcriptional Units: Include exons (coding) and introns (non-coding) within genes.

  • Transcription Overview:

    • Occurs in the nucleus; RNA polymerase binds to DNA and synthesizes mRNA.
    • Modifications include capping and polyadenylation of mRNA.

  • Gene Expression Regulation:

    • Not all genes are active in every cell; they vary based on cellular function.
    • Includes interactions of transcription factors, non-coding RNAs (e.g., microRNA), and epigenetic modifications.
    • Epigenetics refers to heritable changes that affect gene expression without altering the DNA sequence.

  • Translation Process:

    • mRNA associates with ribosomes to synthesize proteins from amino acids.
    • Initiation of translation begins at a start codon (AUG), and ends at stop codons (UGA, UAG, UAA).

  • Protein Misfolding Diseases:

    • Diseases like Alzheimer’s, Huntington’s, and Parkinson’s are associated with misfolded proteins, demonstrating the importance of proper protein synthesis and folding for health.

  • Conclusion on Information Transfer:

    • Overall understanding of DNA structure, transcription, and translation is pivotal for studying human genetics, genetics in medicine, and the implications on various diseases.