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This lecture covers
- Historical perspectives of Microbial Genetics
- Key scientists and their experiments
Gregor Johann Mendel (Jul 20,1822 – Jan 6, 1884)
Austria, Priest, who used 29,000 pea plants to study the variability by crossings.
Developed Law of Segregation and Law of Independent Assortment (also known as law of inheritance). It was not until the early 20th century that the importance of Mendel's ideas was realized.
In 1900, Hugo de Vries, Carl Correns and Erich von Tschermak proved and rediscovered the Mendal’s law.
Later, he was recognized as Father of Genetics (For more details) (Wikipedia)
Walter Stanborough Sutton (April 5, 1877 - November 10, 1916)
was an American geneticist and physician whose most significant contribution to present-day biology was his theory that the Mendelian laws of inheritance could be applied to chromosomes at the cellular level of living organisms. This is now known as the Boveri-Sutton chromosome theory. Wikipedia for more details
Thomas Hunt Morgan (September 25, 1866 – December 4, 1945)
was an American evolutionary biologist, geneticist and embryologist and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries relating the role the chromosome plays in heredity. He proved that genes are carried on chromosome through his experiment on “Sex-linked inheritance of white eyed fruit fly”. (More details about sex linked inheritance [Link 1] [Link 2]
Hermann Joseph Muller (December 21, 1890 – April 5, 1967)
was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation (X-ray mutagenesis) [More details in Wikipedia]
George Beadle and Edward Tatum (1930)
Analyzed mutants of Neurospora, a fungus with a haploid genome (a bread mold). They produced some organisms with mutant genes, then crossed (or mated) those mutants with normal organisms. By doing that, they were able to show that the mutants had lost use of a specific gene that ordinarily facilitates one particular enzyme necessary to the production of arginine. The point was to show how genes direct the synthesis of enzymes that control metabolic processes. It showed that a specific gene coded for a specific enzyme, known as “One Gene – One Enzyme concept”. In 1958 they won the Nobel Prize for their work. [More details]
Read about: Beadle and Tatum Experiment (Wikipedia)
Youtube video by Kelly Hollis
Youtube video from Mcgraw Hill
Frederick Griffith (1879–1941) was a British bacteriologist whose focus was the epidemiology and pathology of bacterial pneumonia. In January 1928 he reported what is now known as Griffith's Experiment, the first widely accepted demonstrations of bacterial transformation, whereby a bacterium distinctly changes its form and function. The observation was attributed to an unidentified transforming principle or transforming factor. This was later identified as DNA. More about Griffith (Wikipedia)
Youtube video about Griffith's experiment to prove that DNA is the genetic element and transformation
Oswald Avery, Colin MacLeod, and Maclyn McCarty (1944)
Conducted experiments and proved that DNA is the substance that causes bacterial transformation. It was the culmination of research in the 1930s and early 1940s at the Rockefeller Institute for Medical Research to purify and characterize the "transforming principle" responsible for the transformation phenomenon first described in Griffith's experiment of 1928. [More details about their experiments in Wikipedia]
Youtube on Avery-MacLeod-McCarty experiment
Erwin Chargaff (Aug 11, 1905 – Jun 20, 2002)
was an Austrian biochemist who immigrated to the United States was a Professor of biochemistry at Columbia University medical school. Through careful experimentation, Chargaff discovered two rules that helped lead to the discovery of the double helix structure of DNA. The first rule holds that a double-stranded DNA molecule globally has percentage base pair equality: %A = %T and %G = %C. The second rule holds that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands. (It means that the composition may vary for single strand of DNA). [Details in Wikipedia]
Alfred Hershey and Martha Chase (1952)
helped to confirm that DNA was the genetic material. While DNA had been known to biologists since 1869, a few scientists still assumed at the time that proteins carried the information for inheritance. In their experiments, Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. [More about them in Wikipedia]
View the video for complete history of DNA discovery
James D. Watson and Francis Crick
were the two co-discoverers of the structure of DNA in 1953. They used x-ray diffraction data and proposed the double helix or spiral staircase structure of the DNA molecule. Their article, Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, is celebrated for its treatment of the B form of DNA (B-DNA), and as the source of Watson-Crick base pairing of nucleotides. They were, with Maurice Wilkins, awarded the Nobel Prize in Physiology or Medicine in 1962. [More about James D Watson and Francis Crick]
Complete structure of DNA as proposed by Watson and Cric
Arthur Kornberg (March 3, 1918 – October 26, 2007)
was an American biochemist who won the Nobel Prize in Physiology or Medicine 1959 for his discovery of "the mechanisms in the biological synthesis of deoxyribonucleic acid (DNA)" together with Dr.Severo Ochoa of New York University.
Matthew Stanley Meselson with Frank Stahl (1958)
American geneticist and molecular biologist whose research was important in showing how DNA replicates, recombines and is repaired in cells.
conducted the famous Meselson-Stahl experiment showing that DNA is replicated by a semi conservative mechanism, meaning that each strand of the DNA serves as a template for the "replicated" strand.
R. Holley, Har Gobind Khorana and Marshall Nirenberg (1968)
Cracked the genetic code (codons for amino acid sequence)
Cracking the code of life paved the way for a tremendous boom in molecular biology, enabling scientists to put together strings of DNA and RNA to produce selected proteins.
Jerome Vinograd (1963)
Properties of closed circular DNA. Supercoiling of DNA
Herbert Boyer (1970)
He discovered that genes from bacteria could be combined with genes from eukaryotes. (Recombinant DNA molecule)
the first-ever synthesis and expression of a peptide-coding gene
synthetic insulin using his new transgenic genetically modified bacteria.
Frederick Sanger (born 13 August 1918) is an English biochemist and a two-time Nobel laureate in chemistry, the only person to have been so.
In 1958 he was awarded a Nobel prize in chemistry "for his work on the structure of proteins, especially that of insulin".
In 1980, Walter Gilbert and Sanger shared half of the chemistry prize "for their contributions concerning the determination of base sequences in nucleic acids". [Wikipedia for more details]
Animation about Sanger's DNA sequencing
Walter Gilbert and Allan Maxam
Developed a new DNA sequencing method
Gilbert first proposed the existence of introns and exons and explained the evolution of introns.
Gilbert proposed the RNA world hypothesis for the origin of life
Youtube videos about Maxam Gilbert sequencing
Sir Richard John Roberts
is a British biochemist and molecular biologist. He was awarded the 1993 Nobel Prize in Physiology or Medicine with Phillip Allen Sharp for the discovery of introns in eukaryotic DNA and the mechanism of gene-splicing.
Max Ludwig Henning Delbrück (September 4, 1906 – March 9, 1981) was a German-American biophysicist. He won theNobel prize for discovering that bacteria become resistant to viruses (phages) as a result of genetic mutations. (Wikipedia)
With Salvador Luria, conducted fluctuation test to demonstrate the natural (spontaneous) mutation. [More about fluctuation test]
Kary Banks Mullis (born December 28, 1944)
is a Nobel Prize winning American biochemist, author, and lecturer. In recognition of his improvement of the polymerase chain reaction (PCR) technique, he shared the 1993 Nobel Prize in Chemistry with Michael Smith and earned the Japan Prize in the same year.
Félix d'Herelle (April 25, 1873 – February 22, 1949)
was a French-Canadian microbiologist, the co-discoverer of bacteriophages (viruses that infect bacteria) and experimented with the possibility of phage therapy.
Joshua Lederberg (May 23, 1925 – February 2, 2008)
was an American molecular biologist known for his work in microbial genetics, artificial intelligence, and the United States space program. He was just 33 years old when he won the 1958 Nobel Prize in Physiology or Medicine for discovering that bacteria can mate and exchange genes (Bacterial conjugation). He shared the prize with Edward L. Tatum and George Beadle who won for their work with genetics. [Wikipedia]
Animation about bacterial conjugation
Norton David Zinder (November 7, 1928 – February 3, 2012)
was an American biologist famous for his discovery of genetic transduction
Esther Miriam Zimmer Lederberg (December 18, 1922 – November 11, 2006)
was an American microbiologist and immunologist and pioneer of bacterial genetics. Notable contributions include the discovery of the lambda phage, the relationship between transduction and lambda phage lysogeny, the development of replica plating, and the discovery of bacterial fertility factor F. [Wikipedia]
How to do replica plating technique
Sir Alec John Jeffreys
is a British geneticist, who developed techniques for DNA fingerprinting and DNA profiling which are now used all over the world in forensic science to assist police detective work, and also to resolve paternity and immigration disputes.
Ribosomes
Together with Albert Claude and Christian de Duve, George Emil Palade was awarded the Nobel Prize in Physiology or Medicine, in 1974, for the discovery of the ribosomes. The Nobel Prize in Chemistry 2009 was awarded to Venkatraman Ramakrishnan, Thomas A. Steitz and Ada E. Yonath for discovering the detailed structure and mechanism of the ribosome.
Taq Polymerase
Thomas Dale Brock is an American microbiologist known for his discovery of hyperthermophiles living in hot springs at Yellowstone National Park. [Wikipedia]
Taq polymerase is a thermostable DNA polymerase named after the thermophilic bacterium Thermus aquaticus from which it was originally isolated by Thomas D. Brock in 1965. It is often abbreviated to "Taq Pol" (or simply "Taq"), and is frequently used in polymerase chain reaction (PCR), a method for greatly amplifying short segments of DNA.
Some key points about Taq Polymerase
RNA Polymerase
RNAP was discovered independently by Samuel B. Weiss, Audrey Stevens, and Jerard Hurwitz in 1960. By this time, one half of the 1959 Nobel Prize in Medicine had been awarded to Severo Ochoa for the discovery of what was believed to be RNAP, but instead turned out to be polynucleotide phosphorylase. The 2006 Nobel Prize in Chemistry was awarded to Roger D. Kornberg for creating detailed molecular images of RNA polymerase during various stages of the transcription process.
Mutagens
Hermann Muller demonstrated the mutagenic effect of x-rays
Edgar Altenburg demonstrated the mutational effect of UV radiation in 1928
Charlotte Auerbach and J. M. Robson, found that mustard gas can cause mutations
Restriction endonucleases
Daniel Nathans, Werner Arber, and Hamilton O. Smith
the 1978 Nobel Prize for Physiology or Medicine was awarded to them. Their discovery led to the development of recombinant DNA technology that allowed, for example, the large scale production of human insulin for diabetics using E. coli bacteria
tRNA
The existence of tRNA was first hypothesized by Francis Crick, based on the assumption that there must exist an adapter molecule capable of mediating the translation of the RNA alphabet into the protein alphabet. The cloverleaf structure was ascertained by several other studies in the following years and was finally confirmed using X-ray crystallography studies in 1974. Two independent groups, Kim Sung-Hou working under Alexander Rich and a British group headed by Aaron Klug, published the same crystallography findings within a year.
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