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In 1865 Mendel delivered two long lectures that were published in 1866 as "Experiments in Plant Hybridisation." This paper established what eventually became formalized as the Mendelian laws of inheritance:These ideas are not recognized for 34 years It will be years before Mendel’s intellectual seeds took root in the grounds of Darwinism and grew into a scientific revolution.
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DNA (first called "nuclein") is identified by Friedrich Miescher as an acidic substance found in cell nuclei. The significance of DNA is not appreciated for over 70 years.
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In 1902, Garrod published a book called The Incidence of Alkaptonuria: a Study in Chemical Individuality. This is the first published account of a case of recessive inheritance in humans. Garrod attributed a biochemical role to genes, and laid the groundwork for the next wave of discovery — the molecular basis of inheritance.
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Using fruit flies as a model organism, Thomas Hunt Morgan and his group at Columbia University showed that genes, strung on chromosomes, are the units of heredity.They showed that chromosomes carry genes, discovered genetic linkage - the fact that genes are arrayed on linear chromosomes - and described chromosome recombination.
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George Beadle and Edward Tatum, through experiments on the red bread mold Neurospora crassa, showed that genes act by regulating distinct chemical events - affirming the "one gene, one enzyme" hypothesis. For their work, Beadle and Tatum shared, with J. Lederberg, the 1958 Nobel Prize in Physiology or Medicine.
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Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA (not proteins) can transform the properties of cells, clarifying the chemical nature of genes.That DNA is the molecule that mediates heredity
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At Cambridge University, scientists James D. Watson and Frances H.C. Crick announce that they have determined the double-helix structure of DNA, the molecule containing human genes.Watson, Crick received the Nobel Prize for Physiology or Medicine in 1962.
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Joe Hin Tjio defined 46 as the exact number of human chromosomes. His discovery helped pave the way to much work in human biology pertaining to chromosomal abnormalities.
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Matthew Meselson and Franklin Stahl show that DNA replicates semi conservatively, that each strand in a DNA moleculecomes from the parent generation pairing with a new strand in the daughter generation. Each "parent" strand of DNA served as a template for the synthesis of a new strand of DNA.
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1966: Genetic Code Cracked. Over the course of several years, Marshall Nirenberg, Har Khorana and Severo Ochoa and their colleagues elucidated the genetic code - showing how nucleic acids with their 4-letter alphabet determine the order of the 20 kinds of amino acids in proteins. They won the 1968 Nobel Prize in Physiology or Medicine "for their interpretation of the genetic code and its function in protein synthesis."
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Genetic engineering using living organisms was first accomplished by Herbert Boyer, and Stanley Cohen, they reported the construction of functional organisms that combined and replicated genetic information from different species. Their experiments dramatically demonstrated the potential impact of DNA recombinant engineering on medicine
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Kary Mullis is generally credited with inventing PCR, The polymerase chain reaction is a technique for amplifying DNA that dramatically boosted the pace of genetic research. Gene cloning, sequencing of complex genomes, DNA fingerprinting and DNA-based diagnostics are just some of the techniques that were either inefficient, crude or plain impossible before PCR.Mullis received the Nobel Prize for his ground-breaking invention
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the United States, along with several other countries, launched the Human Genome Project. The main goals: to sequence all 3 billion base pairs of human DNA and identify all human genes. Other important goals included: sequencing the genomes of model organisms to interpret human DNA, developing technology to support the research, exploring gene functions, studying human variation, and training future scientists.
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"Understanding the complete set of genes spelled out in human DNA promises to usher in a new era of molecular medicine, with precise new approaches to the diagnosis, treatment, and prevention of disease," says Dr. Francis Collins, director of the NCHGR , and supporter of the Whitehead/MIT Center for Genome Research.
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The first cloning of a mammal, Dolly the sheep,was performed by Ian Wilmut and colleagues, from the Roslin institute in Scotland. This was the world's first successful cloning experiment. It was the birth of the first mammal cloned from an adult cell.
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Scientists, led by Pasqualino Loi, of the University of Teramo, Italy, successfully created a viable clone of an endangered species—the European mouflon, one of the smallest wild sheep in the world. The mouflon lamb was cloned using "somatic cell nuclear transfer"—the same technique used in 1997 to clone Dolly. The only difference is that this time two species of sheep were used—the mouflon that was cloned and the domestic surrogate mother that carried the clone.
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This was achieved by Shoukhrat Mitalipov at Oregon Health & Science University in Portland, and If the same can be done with human cells, ES cell lines could be created that are genetically identical to a patient with a particular disease. These cells could then be used to study the disease or, perhaps, grown to produce replacement tissues that would not be rejected.
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Shoukhrat Mitalipov, a reproductive biology specialist at the Oregon Health and Science University in Beaverton, and his colleagues have finally created patient-specific ESCs through cloning, and they are keen to prove that the technology is worth pursuing.
