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Period: to
Genetic Discoveries between 1800 & 2000
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On the Origin of Species
Charles Darwin published his book, On the Origin of Species -
Basic Laws of Inheritance
Gregor Mendel published his book, Experiments in Plant Hybridization (a combination of 2 papers written in 8-Feb-1965 and 8-Mar-1965), laying the basic laws of inheritance after excuting a series of experiments using peas. These are:
1- That each feature operate alone, i.e traits are not linked.
2- For each characteristic, the off spring gains 1 alleles from each parent.
3- For each characteristic, there is a dominant feature and a recessive feature in a ratio 3:1. -
DNA
Johann Friedrich Miescher extracts what comes to be known as DNA from the nuclei of white blood cells. -
Discovering How Chromosomes Work
Theodor Boveri started investigatin chromosomes in 1887, he made a series of important observations including:
1- They keep the same arrangement and shape before and after mitosis.
2- Sperms and eggs donate the same number of chromosomes. -
Inheritance
Rediscovery of Mendel's work clarified inheritance. Boveri had already shown how chromosomes behave during reproduction, he made a series of experiments and wrote this conclusion in 1902, "specific assortment of chromosomes is responsible for normal development and this can mean only that the individual chromosomes possess different qualities".
Walter Sutton came to the same conclusion and in 1902 but with working with meiosis not mitosis. -
Inherited Diseases
Archibald E. Garrod was interested in rare diseases found in the population, he discovered that they were not bacterial infections as was commonly believed and that they were more common in children of first cousin marriages. This matched the discription of recessive inheritance described my Mendel. 50 years would pass before anyone recognize and understand Garrod's work. -
What Chromosomes are Made of
Oswald T. Avery showed that a nucleic acid, deoxyribonucleic acid (DNA), is what chromosomes are made of rather than the common belief at that time that they were made from proteins. -
Structure of DNA
James Watson and Francis Crick co-discovered the structure of DNA, they famously noted that "the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material." -
Molecular Biology
Francis Crick argued that the main function of genes is the synthesising of proteins from amino acids. He proposed 2 general principles:
1- The Sequence Hypothesis: the structure of protien is encoded in the genes, and how these "words" are translated in 3D proteins.
2- The Central Dogma: Information is transported from DNA & RNA to protein, but not the other way round. -
Cracking the Genetic Code
Marshall Nirenberg discovered the first "triplet", a sequence of three bases of DNA that codes for one of the twenty amino acids, by doing an experiment with Johann Matthaei and concluded that the RNA sequence "UUU" directs the addition of phenylalanine to any growing protein chain. Nirenberg then went on and to decipher other triplets in the genetic code, discovering over 60 by 1966. -
Gene Extraction
Jonathan Beckwith isolates a bacterial gene. -
DNA from RNA
David Baltimore discovered reverse transcriptase, an enzyme that makes DNA from an RNA template; enzymatic isolation of DNA will become important for genetic engineering. -
Cloning DNA
Stanley Cohen and Herbert Boyer developed recombinant DNA technology, showing that genetically engeineered DNA can be cloned in foreign cells using E.coli bacteria and developing a coloney which was resistant to more than 1 disease. -
Sequencing DNA
Walter Gilbert and Fedrick Sanger each devised a method of sequencing DNA, that is the order of A, G, T, and U. -
DNA fingerprinting
Alec Jeffreys:
-discovered that each individual all varies greatly and the pattern appeared to be unique[11]-developed techniques for DNA fingerprinting and DNA profiling
