Introduction gen and bioengineering 2

Introduction to Genetics

  • Genetics: A discipline of biology that focuses on the science of genes, heredity, and variation in living organisms.

    • Involves the molecular structure and function of genes.

    • Studies gene behavior in the context of a cell.

  • Etymology: The term genetics comes from the Ancient Greek word γενετικός (genetikos), meaning "generative", derived from γένεσις (genesis) meaning "origin".

Understandings Before Mendel's Time

  1. All Life Comes from Other Life: No spontaneous generation from non-living materials, except during the origin of life.

  2. Species Concept: Only members of the same species can mate to produce fertile offspring.

  3. Development Through Heredity: Organisms develop by expressing hereditary information, opposing the idea of "preformation" (a fully formed human in sperm/egg).

  4. Environment and Heredity: The environment cannot alter hereditary material systematically; mutations are random events.

  5. Parental Contribution: Male and female parents contribute equally to offspring.

Major Discoveries in the Mid-1800s

  • 1859: Charles Darwin publishes The Origin of Species, outlining natural selection which necessitates heredity.

  • 1866: Gregor Mendel's Experiments in Plant Hybridization lays the groundwork for genetics, although largely ignored until 1900.

Charles Darwin

  • Theory of Evolution: Proposed all species descend from common ancestors through natural selection.

Gregor Johann Mendel: The Father of Genetics

  • Conducted hybridization experiments with garden peas (1856-1863).

  • Cultivated and tested approximately 5,000 pea plants.

  • Established Mendel's Principles of Heredity, described in his paper presented to the Natural History Society of Brno.

Mendel's Laws of Inheritance

1. Law of Segregation

  • During gamete formation, alleles segregate so each gamete has one allele per gene.

2. Law of Independent Assortment

  • Genes for different traits segregate independently during gamete formation.

3. Law of Dominance

  • Some alleles are dominant and overshadow recessive alleles; dominant alleles show their effect when present.

Rediscovery of Mendel's Work in the 20th Century

  • 1900: Mendel's principles are rediscovered by Robert Correns, Hugo de Vries, and Erich von Tschermak.

  • 1904: Gregory Bateson identifies gene linkage and coins the term 'genetics'.

  • 1910: Thomas Hunt Morgan confirms gene location on chromosomes using Drosophila studies.

Griffith's Experiments (Year Noted)

  • Explored bacterial colonies demonstrating transformation between virulent and nonvirulent strains.

  • Findings illustrated the role of DNA in heredity.

Contributions by Avery and Colleagues (1944)

  • Avery, MacLeod, and McCarty's experiments revealed that DNA is the hereditary material by showing that it can transform bacteria.

Chargaff's Base Pair Discovery

  • Erwin Chargaff found ratios of base pairs: Adenine equals Thymine, and Cytosine equals Guanine.

  • Suggested that bases pair with one another (A-T and C-G).

Linus Pauling's Discoveries

  • Discovered protein helix structures (1951), informing DNA structure determination by other scientists.

X-ray Crystallography by Wilkins and Franklin

  • Rosalind Franklin and Maurice Wilkins utilized X-ray crystallography, providing pivotal clues about DNA's helical structure.

Watson and Crick's Model of DNA

  • Collaborated with Wilkins and utilized Chargaff's pairing rule.

  • Constructed a model of DNA, though with controversy regarding data use from Franklin.

Modern Developments in Genetics

  • 1966: Marshall Nirenberg deciphers the genetic code mapping 3 DNA bases to amino acids.

  • 1972: Cohen and Boyer first cloned DNA from different species in vitro.

  • 1983: Kary Mullis develops the Polymerase Chain Reaction (PCR) method.

  • 1990-2003: The Human Genome Project marks significant advances in genetics research.

Genetic Technologies and Techniques

  • CRISPR and gene editing technologies allow targeted manipulations of genomes.

  • Branches of Genetics: Include behavioral, classical, developmental, ecological, evolutionary, medical, molecular, population genetics, and more.