L05_ The Human Genom-audio

Overview of Evolution Theory

  • Evidence supporting evolution theory is reliable, robust, and reproducible.

  • Change in understanding from linear evolution to diverging lineages.

  • Nucleic acid information (DNA sequencing) is the key source of information in evolution studies.

Human Genome Project Introduction

  • Human Genome Project initiated in 1986; genomic era began in 1995:

    • 1995: First complete genome sequence of a prokaryote by Jane Craig Venter's lab (Haemophilus influenzae).

    • Random mechanical fragment sequencing followed by compilation through computer algorithms.

    • First publication in Science journal.

  • Venter's promotion and ego highlighted in the lab’s name change.

  • Description of the initial sequencing of both prokaryotic and eukaryotic organisms subsequently followed.

Major Milestones of the Human Genome Project

  • Timeline: 1986 - 2003, with major milestones:

    • 1996: ...

    • 2001: First draft of the Human Genome was published but not complete.

    • 2003: Completion of the Human Genome Project, with over 99% of the genome sequenced.

Key Findings and Comparisons

  • Early results indicated humanity's genetic similarity with:

    • Bacteria: Shared genes identified but with modest relatedness.

    • Eukaryotes: Close relations with yeast and multicellular organisms, leading to better understanding of genetics.

  • First shock: Estimated 100,000 genes in humans, only 22,000 identified.

  • Second shock: 95% of DNA is non-coding, challenging prior assumptions.

Haploid genome is 3.2×109 bp long.

Benifits of the human genome project: Helps to understand our evolutionary history, Human and chimpanzee genomes can be compared to identify genes that contribute to uniquely human traits.

Progression and Findings Post Human Genome Project

  • Draft genome in 2001 eventually led to:

    • Genetic insights into ancient relatives like Neanderthals in 2010.

    • 1,000 Genomes Project mapped human genetic variation, leading to implications for medical advancements.

  • Example: Predictive tests for breast cancer arose from genomic access.

Ethical Considerations in Genomic Study

  • Ethical issues in genetic information storage and potential misuse by employers or insurers.

  • Psychological effects of acquiring personal genetic risk information.

  • Stigmatisation.

The Central Dogma of Molecular Biology

  • Defined by Francis Crick in 1958 highlighting:

    • DNA -> RNA -> Protein as the flow of genetic information.

  • Acknowledges RNA viruses and potential backflow of information.

  • Main route is DNA replication, transcription (into RNA) and then translation (into protein). However also have RNA replication (e.g. copies info like RNA viruses) and reverse transcription (RNA to DNA, e.g. retroviruses)

Understanding Genes and Inheritance

Mendel's Experiments and Laws

  • Why did he choose peas?

    • Produce large numbers of offspring.

    • Short generation time.

    • Both self and cross fertilisation are possible.

  • Gregor Mendel's foundational pea plant experiments informed genetic inheritance principles:

    • Observed dominant and recessive traits through controlled crossings.

    • Introduced the concepts of segregation and alleles.

  • Highlighted the significance of test crosses in confirming genetic ratios.

  • Comparison of traits like seed color revealed predicted inheritance patterns.

  • Before was thought that characteristics from parents were blended ; however, it is now understood that traits are inherited as discrete units, known as alleles.

  • The first law of inheritance; law of segregation

    • If alleles are identical, homozygous.

    • If alleles are different, hetrozygous.

    • One allele from each parent,

  • Chromosomal Basis of Genetics

  • Chromosome observations by Walter Sutton in 1902 linked Mendel’s factors to chromosome behavior during meiosis.

  • T.H. Morgan furthered this understanding with Drosophila melanogaster studies, showing non-reciprocal inheritance patterns in eye color.

Conclusion and Future Topics

  • Genome sequencing established a foundational understanding of genetic inheritance.

  • Future lessons will focus on gene functions, their regulatory roles, and implications for personalized medicine.

  • Emphasis on continued learning regarding genetic material starting from foundational knowledge to practical applications.