Molecular genetics is the field of biology that study of genetic material at a molecular level where biological information is stored, copied, repaired and decided to create protein and other molecules within cells and tissues.

The study of chromosomes and gene expression of an organism can give insight into heredity, genetic variation, and mutations. This is useful in the study of developmental biology and in understanding and treating genetic diseases.

Here are some important events which contributed to developing molecular genetics:

1. Friedrich Miescher, 1869

  • Extracted a viscous white substance from the nucleus of a cell.
  • The substance was slightly acidic and rich in phosphorous and nitrogen.
  • Named it nuclein because it was found in the nucleus.

2. Frederick Griffith, 1920

  • Tried to develop a vaccine against pneumonia.
  • Discovered transformation.

3. Joachim Hammerling,1930

  • Studied one-celled green alga Acetabulariato determine the location of DNA within the cell.

4. Oswald Avery, Maclyn McCarty and Colin McLeod, 1944

  • Continued the work of Griffith and Ruptured heat-killed encapsulated cells to release their content. Each component (DNA, RNA, protein) was isolated and tested for transforming ability.
  • Determined that protein is not the hereditary material but instead DNA is the material of which genes and chromosomes are made.

5. Erwin Chargaff, 1950

  • Studied DNA in many different organisms and Helped lead to the discovery of the double helix structure of DNA.
  • Found that the composition of DNA varies from one species to another, in particular in the relative amounts of A, G, T, and C bases.
  • The proportion of Adenine in a DNA molecule is equal with to that Thymine, and the proportion of Guanine is equal to that of Cytosine.

6. Alfred Hershey & Martha Chase, 1952

  • Found virus infects a bacterial host by attaching to the surface of the cell and injecting its DNA into the cell.
  • Prove that only the DNA from the virus, not the protein.

7. Rosalind Franklin, 1953

  • Discovered that the sugar-phosphate backbone of DNA lies on the outside of the molecule, not the inside as was previously thought

8. James Watson & Francis Crick, 1950

  • Postulatemolecular structure of DNA together from a variety of sources including Franklin and Chargaff.

9. Matthew Meselson & Franklin Stahl,1958

  • Discovered that DNA replication is semi-conservative.

10. Human Genome Project, 1990

  • This project was done by United States Department of Energy and the U.S. National Institute of Health and was expected to take 15 years.
  • Cost of project was $3 billion.
  • The ultimate goal was to “understand the human genome” and gain “knowledge of the human as necessary to the continuing progress of medicine and other health sciences”.
  • Over 3 billion base pairs studied in this project.

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