Genetics

• Genetic variation can arise from mutations, which are changes in the DNA sequence of a gene.
• Genetics is the branch of biology that deals with the principles of heredity and variation in all living things.
• Genetics is the study of genes.
• Regulation is required but it needs to be fully informed by science.
• Genetic Discrimination- the case for a European-level legal response
• Genetic technologies have huge potential to benefit mankind but can be abused.
• In 1953, James Watson and Francis Crick published the double helix model for DNA’s chemical structure.
• In the 1860s, Mendel’s work on peas allowed the conclusion that traits are inherited through discrete units passed from one generation to the next.
• In the 1870s, Friedrich Miescher described nucleic acids.
• Thomas Morgan’s work on fruitflies demonstrated that genes lie on chromosomes.
• In the 1940s, Barbara McClintock described mobile genetic elements in maize.
• In 1958, Crick proposed the ‘central dogma’ for biological information flow: that DNA makes RNA makes protein.
• The word ‘gene’ was coined by Danish botanist Wilhelm Johannsen in 1944.
• In 1909, Oswald Avery showed in bacteria that nucleic acids are the ‘transforming principle’.
• In 1977, Phillip Sharp and Richard Roberts found that protein-coding genes are carried in segments.
• In 2001, initial results from the Human Genome Project were published.
• Gregor Mendel, the Father of Genetics, discovered that hereditary characteristics were determined by elementary “factors” (now called genes) that are transmitted between generations in uniform predictable fashion.
• Mendel demonstrated that the appearance of different characters in heredity followed specific laws that could be determined by counting the diverse kinds of offspring produced from any particular set of crosses.
• August Weismann (1834-1914) first challenged the theory of Pangenesis.
• The choice of garden peas (Pisum sativum L.) as the experimental material was an advantage as they are self-pollinated, producing large numbers of seeds, and their traits have clear-cut differences.
• Charles Darwin (1809-1882) believed in the theory of Pangenesis, which was prevalent in the 19th century.
• Carl Correns in Germany, Erick Von Tschermak in Austria and Hugo de Vries in the Netherlands duplicated Mendel’s experiments on garden peas, maize, primroses, poppies and many other flowering plants, obtaining the same ratios as those of Mendel and providing the follow-up work that Mendel was not able to do.
• Mendel formulated theories that explained his experimental results and appropriate experimental tests to validate his theories.
• Mendel’s Plant Breeding Experiments involved seven years of breeding pea plants and recording inheritance patterns in the offspring.
• In the early 1800’s, the blending hypothesis was proposed, stating that genetic material contributed by the two parents mixes in a manner analogous to the way blue and yellow paints blend to make green.
• Jean Baptiste de Lamarck (1744-1829) proposed his Theory of Inheritance of Acquired Characteristics based on the Pangenesis theory.
• Mendel concentrated on a single trait at a time, observing whole plants or more complex traits.
• The Germplasm Theory proposed that germplasm or sex cells perpetuate themselves in reproduction generation after generation.
• The particulate hypothesis of inheritance states that parents pass on to their offspring separate and distinct factors (today called genes) that are responsible for inherited traits.
• Mendel chose to work with peas because they are available in many varieties and the use of peas gave Mendel strict control over which plants mated.
• To test the particulate hypothesis, Mendel crossed true-breeding plants that had two distinct and contrasting traits—for example, purple or white flowers.
• Mendel cross-fertilized his plants by hand.
• For each monohybrid cross, Mendel cross-fertilized true-breeding plants that were different in just one character—in this case, flower color.
• Mendel allowed the hybrids (the F1 generation) to self-fertilize.
• The F2 generation is produced when the F1 hybrids self-pollinate.
• Mendel studied seven characteristics in the garden pea.
• Statistics indicated a pattern.
• Multifactorial; many factors, both genetic and environmental, collectively influence phenotype in examples such as skin tanning.
• Thomas Hunt Morgan and Calvin Bridges confirmed the Chromosome Theory of Inheritance by the discovery of sex chromosomes.
• Oswald T. Avery, Collin M. MacLeod, and Maclyn McCarty identified the deoxyribonucleic acid (DNA) as the hereditary material.