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DNA Discovery Timeline

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Cindy Tran

on 26 November 2013

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Transcript of DNA Discovery Timeline

DNA Discovery Timeline
By:Cindy Tran

- Mendel was an Austrian botanist and through his experiment with pea plants he discovered inheritance "factors" and patterns.(3)
- Mendel's Laws of Heredity:
1) The Law of Segregation : genes defines inherited traits. Parental genes are randomly separated to the sex cells.
2) The Law of Independent Assortment: Genes for different traits are separate from one another.Inheritance of one trait is not dependent on the inheritance of another.
3) The Law of Dominance : There are 2 types of genes recessive and dominant. Genes will express the form that is dominant. (2)
- He concluded that genes come in pairs and are inherited, one gene from each parent.(2)
Gregor Mendel 1866
Frederick Griffith 1928
- British microbiologist Frederick Griffith published his landmark paper in 1928.(3)
-Griffith's experiment involved mice and two types of pneumonia. In his experiment he found that even though he killed the bacteria with heat, the killed virulent bacteria had passed on a characteristic to the non-virulent one to make it virulent.This passing on of the inheritance molecule DNA, he called transformation. He proposed a principle transformed the harmless R strain of Diplococcus to the virulent S strain.(1,4)
- The importance of his paper was further researched by Oswald Avery and others who concluded that deoxyribonucleic acid (DNA) carries information within the cell.(3)
Walther Flemming 1882
-Walther Flemming was a German anatomist and founder of the science of cytogenetics,the study of the cell’s hereditary material, the chromosomes. He was the first to observe and describe the behaviour of chromosomes in the cell nucleus during cell division.(9)
-Upon examining under a microscope,he discovered the sequence of changes in the nucleus during cell division and named the process mitosis.(9)
-Flemming’s work for heredity was not acknowledged fully until the work of Gregor Mendel’s principles of heredity were recognized.(9)
Phoebus Levene 1929
-Phoebus Levene was a Russian-born American chemist, his studies involved mainly of organic compounds (5)
- He isolated nucleotides and in 1909 and separated the five-carbon sugar d-ribose from the ribonucleic acid (RNA) molecule. Twenty years later he discovered 2-deoxyribose which is part of the DNA molecule. (5)
- His work work at the time was unrecognized however became the groundwork for later discoveries that showed DNA and RNA are key elements in the maintenance of life.(5)
Oswald Avery, Colin MacLeod,
Maclyn McCarty 1944
-Oswald Avery was a Canadian-born American physician and medical researcher. His collegues were Colin MacLeod and Maclyn McCarty who were American biologist.(6)
-In 1944 his team reported that the transforming principle in Griffith's experiment was DNA.(1)
-It was skeptical at the time since many scientists believed proteins were responsible for hereditary information, however, the role of DNA was proven throughout the years and was recognized later on.(6)
Hershey and Chase 1952
-Alfred Hershey was an American biologist and Martha Chase worked on the blender experiment that proved it was DNA and not protein that was the carrier of genetic information.(7)
-In their experiment they used an ordinary kitchen appliance and used phage viruses. The phage had a radioactive protein coat but when they infected a bacterial cell, the radioactive protein coat stayed on the outside and only DNA was transferred inside.(8)
-They found that the protein coats were not involved in viral replication in bacterial cells but DNA was since the new Phge viruses in the bacterial cell contained no radioactive material. (8)
-Erwin Chargaff was an Austrian biochemist who noticed a pattern in the four bases: adenine, guanine, cytosine, and thymine of DNA. (4)
-He took samples of DNA of different cells and found that the amount of adenine was almost equal to the amount of thymine, and that the amount of guanine was almost equal to the amount of cytosine.(4)
-This discovery later became Chargaff’s Rule that A=T and G=C.(1)
Erwin Chargaff 1950
-Rosalind Franklin was a British scientist who helped model the molecular structure of deoxyribonucleic acid (DNA).(10)
-In the 1950's she studied X-ray diffraction technology and applied those methods to study DNA. While working she obtained sharp X-ray diffraction photographs of DNA.(1)
-She discovered through her X-rays that the DNA molecule was in a helical conformation.
-Her work was the foundation for James Watson and Francis Crick to suggest the structure of DNA is a double-helix polymer.(10)
Rosalind Franklin 1951
-Bruce Ames was an American biochemist and geneticist who developed the Ames test for chemical mutagens. (11)
-The test was able to determine the ability of chemicals to induce mutations in the bacterium Salmonella typhimurium. The test to detect carcinogenic human-made substances led to bans on use of those chemicals.(11)
-The test targets chemical mutagens that tend to increase the frequency or extent of genetic mutation.(11)
Bruce Ames 1970
-Francis Crick was an British biophysicist along with James Watson an American geneticist and Maurice Wilkins a New Zealand-born British biophysicist, received the 1962 Nobel Prize for Physiology or Medicine for their model of the molecular structure for DNA, the double helix.(13)
-Watson and Crick used the stick-and-ball models to test the possible structure of DNA but it was Franklin's X-ray that revealed the helical structure of DNA to Watson and Crick in 1953 that lead to their discovery.(12)
-The 3-D model of DNA became a milestone in the history of genetics and was considered one of the most significant discoveries of 20th-century.(1,13)
Francis Crick & James Watson 1953
-Matthew Meselson, an American molecular biologist and Franklin Stahl, an American geneticist experimentally proved Watson and Crick’s model of semi-conservative replication.(15,16)
-A centrifuge was used to separate bacterial DNA molecules using isotopes of nitrogen in different densities. (1,14)
-Meselson and Stahl gave experimental evidence that each DNA strand served as a template for new synthesis. This was proof that a process called semi-conservative replication occurs in DNA.(14)

Matthew Meselson & Franklin Stahl 1958
-George Beadle, an American geneticist contributed to biochemical genetics when he showed that genes affect heredity by determining enzyme structure along with Edward Tatum an American biochemist.(1,17,18)
-Beadle and Tatum grew and cultured Neurospora,they mutated Neurospora and tested for nutritional deficiencies. After collecting over 1000 samples of irradiated cultures their success was the 299th culture.(2)
-Beadle and Tatum published their findings and won the 1958 Nobel Prize in Physiology or Medicine proving that irradiating the red bread mold, Neurospora resulted in the gene producing its effect by regulating particular enzymes.(2)
George Beadle & Edward Tatum 1941
1) Lane, Jo Ann. "History of Genetics Timeline." <i>History of Genetics Timeline</i>. Access Exellence, n.d. Web. 24 Nov. 2013. &lt;http://www.accessexcellence.org/AE/AEPC/WWC/1994/geneticstln.php&gt;.

2) "DNA Timeline: DNA Science from Mendel to Today." <i>DNA Timeline: DNA Science from Mendel to Today</i>. Cold Spring Harbor Laboratory , n.d. Web. 24 Nov. 2013. &lt;http://www.dnai.org/timeline/&gt;.

3)"Frederick Griffith." Frederick Griffith. NNDB, n.d. Web. 24 Nov. 2013. <http://www.nndb.com/people/495/000270682/>.

4)"History of DNA Research." ThinkQuest. Oracle Foundation, n.d. Web. 21 Nov. 2013. <http://library.thinkquest.org/20830/Textbook/HistoryofDNAResearch.htm>.

5)"Phoebus Levene (American chemist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 23 Nov. 2013. <http://www.britannica.com/EBchecked/topic/337857/Phoebus-Levene>.

6)"Oswald Avery (American bacteriologist)." <i>Encyclopedia Britannica Online</i>. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. &lt;http://www.britannica.com/EBchecked/topic/45627/Oswald-Avery&gt;.

7)"A.D. Hershey (American biologist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/263850/AD-Hershey>.

8)"Timelines: 1952." <i>The Hershey-Chase blender experiment</i>. N.p., n.d. Web. 24 Nov. 2013. &lt;http://www.lifesciencesfoundation.org/events-The_HersheyChase_blender_experiment.html&gt;.

9)"Walther Flemming (German biologist)." <i>Encyclopedia Britannica Online</i>. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. &lt;http://www.britannica.com/EBchecked/topic/210024/Walther-Flemming&gt;.

10)"Rosalind Franklin (British scientist)." <i>Encyclopedia Britannica Online</i>. Encyclopedia Britannica, n.d. Web. 23 Nov. 2013. &lt;http://www.britannica.com/EBchecked/topic/217394/Rosalind-Franklin&gt;.

11)"Bruce Ames (American biochemist and geneticist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/1939178/Bruce-Ames>.
12) The Discovery of the Molecular Structure of DNA. N.p., n.d. Web. 24 Nov. 2013. <http://www.nobelprize.org/educational/medicine/dna_double_helix/readmore.html>.

13)"Francis Harry Compton Crick (British biophysicist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/142894/Francis-Harry-Compton-Crick>.

14)"Nucleic Acids and the Genetic Material Problem Set." Nucleic Acids and the Genetic Material Problem Set. N.p., n.d. Web. 24 Nov. 2013. <http://www.biology.arizona.edu/molecular_bio/problem_sets/nucleic_acids/06t.html>.

15)"Matthew Stanley Meselson (American biologist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/376583/Matthew-Stanley-Meselson>.

16)"Franklin W. Stahl (American geneticist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/562515/Franklin-W-Stahl>.

17)"Edward L. Tatum (American biochemist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/584284/Edward-L-Tatum>.

18)"George Wells Beadle (American geneticist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/57146/George-Wells-Beadle>.

19)"Arthur Kornberg (American scientist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/322505/Arthur-Kornberg>.

20)"George Wells Beadle (American geneticist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/57146/George-Wells-Beadle>.

21) "Sydney Brenner (South African biologist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/891288/Sydney-Brenner>.

22)"Barbara McClintock (American scientist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/353963/Barbara-McClintock>.

23)"Kary B. Mullis (American chemist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/396935/Kary-B-Mullis>.
-Arthur Kornberg was an American biochemist and physician who received the 1959 Nobel Prize for Physiology or Medicine for discovering how DNA molecules duplicated in the bacterial cell by duplicating this process in a test tube.(19)
-He isolated DNA polymerase I from E. coli and was the first to use this enzyme and make DNA in a test tube.(1)
-Kornberg shared the Nobel Prize for Physiology and Medicine with Severo Ochoa. Kornberg received it for the enzymatic synthesis of DNA, Ochoa for the enzymatic synthesis of RNA.(2)
Arthur Kornberg 1958
-Frederick Sanger was an English biochemist who was the recipient of the Nobel Prize for Chemistry twice. He was awarded the prize in 1958 for his determination of the structure of the insulin molecule. He also received the prize in 1980 for his determination of base sequences in nucleic acids.(20)
- Sanger Developed the chain termination (dideoxy) method for sequencing DNA.(1)
-Initially Sanger worked with proteins but solving DNA sequencing became a natural extension.He started off investigating the sequence of RNA because it was smaller and those techniques were applicable to DNA.(2)
Frederick Sanger 1977
-Sydney Brenner a South-African born biologist along with John E. Sulston and H. Robert Horvitz, won the Nobel Prize for Physiology or Medicine in 2002 for their discoveries about how genes regulate tissue and organ development through a key mechanism called programmed cell death, or apoptosis.(21)
-In the 1960's Brenner researched organ development and related processes in higher animals. It allowed him to follow cell divisions under a microscope and learned about programmed cell death, a mechanism that allows cells to self-destruct when triggered.(21)
- His work laid the foundation for future research on programmed cell death. Sulston and Horvitz both used C. elegans in their studies (a worm) and established them as one of the most important experimental tools in genetics research.(21)
Sydney Brenner 2002
Barbara McClintock late 1940's
-Barbara McClintock,an American scientist whose discovery in the 1940s on mobile genetic elements called “jumping genes,” won her the Nobel Prize for Physiology or Medicine in 1983.(22)
-Barbara McClintock developed the hypothesis of transportable elements to explain color variations in corn by tracing pigmentation changes under a microscope.(1)
-She isolated two genes that she called “controlling elements” and found that they moved along the chromosome to different sites which affected the behaviour of neighbouring genes. This suggested they were responsible for new mutations in pigmentation of the corn.(22)

-Kary B. Mullins was an American biochemist, and was a co-winner of the 1993 Nobel Prize for Chemistry for his invention of the polymerase chain reaction.(PCR) (23)
-Mullins used PCR that consisted of: the double-stranded DNA segment called the template strand to be copied, two oligonucleotide primers; nucleotides, the building blocks that make up DNA; and a polymerase enzyme that joins the free nucleotides in the correct order and when repeating this cycle
produces more than a billion
copies of the original DNA
sequence in mere hours.(23)
-Ian Wilmut was a British
developmental biologist who
worked with Keith Campbell
and use nuclear transfer of
differentiated adult cells to
generate a mammalian clone.
Their success was in 1995
with the cloned Welsh
mountain sheep, Megan
and Morag.(24)
Kary Mullins, Ian Wilmut and Keith Campbell 1985
24)"Sir Ian Wilmut (British biologist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/644616/Sir-Ian-Wilmut>.

25) "Molecular Pathology - Maxam-Gilbert DNA Sequencing." <i>Molecular Pathology - Maxam-Gilbert DNA Sequencing</i>. N.p., n.d. Web. 24 Nov. 2013. &lt;http://www.pathologyoutlines.com/topic/molecularpathdnaseqmaxam.html&gt;.

26)"DNA sequencing (genetics)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/422006/DNA-sequencing#ref1011077>.

27)"Advancing the Science of Genomics." Scientist Spotlight: Hamilton O. Smith and Clyde A. Hutchison III. N.p., n.d. Web. 23 Nov. 2013. <http://blogs.jcvi.org/2010/05/scientist-spotlight-hamilton-o-smith-and-clyde-a-hutchison-iii-2/>.

28) "Affiliations." Clyde A. Hutchison III - a brief career sketch. N.p., n.d. Web. 24 Nov. 2013. <http://www.unc.edu/~clyde/Biopic.html>.

29)"Hamilton Othanel Smith (American biologist)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/549744/Hamilton-Othanel-Smith>.

30)"Article." - The Genome Institute at Washington University. N.p., n.d. Web. 24 Nov. 2013. <http://genome.wustl.edu/articles/detail/dna-sequencing-lays-foundation-for-personalized-cancer-treatment/>.

31)"Inventor of the Week: Archive." <i>Inventor of the Week: Archive</i>. N.p., n.d. Web. 24 Nov. 2013. &lt;http://web.mit.edu/invent/iow/boyercohen.html&gt;.

32)"Genetically modified mouse." <i>Genetically modified mouse</i>. N.p., n.d. Web. 24 Nov. 2013. &lt;http://shelf3d.com/i/Genetically%20modified%20mouse&gt;.

33)"Okazaki and Semidiscontinuous Replication." Okazaki and Semidiscontinuous Replication. N.p., n.d. Web. 24 Nov. 2013. <http://fbio.uh.cu/sites/genmol/adic/okazaki.html>.

34)"Concept 13 Mendelian laws apply to human beings.." Sir Archibald Edward Garrod. N.p., n.d. Web. 24 Nov. 2013. <http://www.dnaftb.org/13/bio.html>.

35)"The work of Mendel." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Nov. 2013. <http://www.britannica.com/EBchecked/topic/228936/genetics/261528/The-work-of-Mendel#toc261531>.
-Maxam-Gilbert method was a DNA sequencing method discovered by American molecular biologists Allan Maxam and Walter Gilbert.(26)
- They developed a gel-based DNA sequencing method called "chemical sequencing", that used 4 base-specific chemical reactions to cut double-stranded DNA fragments (25)
-The DNA fragments were then denatured, run side-by-side in slab gel electrophoresis, autoradiographed and analyzed for their sequence.(25)
Allan Maxam & Walter Gilbert 1976
Friedrich Miescher 1869
-Friedrich Miescher was a Swiss physician and biologist who isolated the first crude preparation of DNA,he named it nuclein – from the cell nucleus and determined it was made up of hydrogen, oxygen, nitrogen and phosphorus.
-He had shyness and a hearing handicap however was very successful in his studies due to his intellectual relatives. (2)
-He believed that proteins were the molecules of heredity. Miescher laid the groundwork for the molecular discoveries that followed after he died of tuberculosis.(2)
Hamilton Smith and Clyde Hutchison 1970's

-Hamilton Smith an American microbiologist won the the Nobel Prize for Physiology or Medicine in 1978 for his discovery of a new class of restriction enzymes. It would recognize specific sequences of nucleotides in DNA.(29)
-Restriction endonucleases are enzymes made by bacteria that cut DNA in specific places, the isolation of these enzymes provided a vital tool for molecular biology research. (27)
-In 1968 Clyde Hutchison, an American biochemist and microbiologist studied Bacteriology and Immunology and analyzed DNA, and the virion proteins. Hutchison in his work applied restriction enzymes to the analysis of mammalian mitochondrial DNA, identifying restriction fragment length polymorphisms, and demonstrating maternal inheritance of mitochondrial DNA in mammals.(28)
-Elaine Mardis is an American Professor of Genetics at Washington University School of Medicine.
-She joined The Genome Institute in 1993 and helped determine methods for sequencing the human genome.(30)
-Mardis' initial interest is to apply DNA sequencing to characterize cancer genomes.(30)
-Scientists at The Genome Institute are using powerful DNA sequencing technology to identify mutations in a patient's tumor and to map the genetic evolution of the disease to find treatment.(30)
Elaine Mardis 1993
-Herbert Boyer, a biochemist and genetic engineer and Stanley Cohen, an associate professor of medicine invented a method of cloning genetically engineered molecules in foreign cells.(31)
-The collaboration began in Hawaii in 1972, Boyer isolated an enzyme that could be used to cut strings of DNA into precise segments while Cohen had a method to introduce antibiotic-carrying plasmids into certain bacteria, as well as a method of isolating and cloning genes carried by the plasmids.(31)
-The medical products from their work are synthetic insulin for diabetes, a clot-dissolving agent for heart-attack victims, and a growth hormone for underdeveloped children.(31)
Herbert Boyer & Stanley Cohen 1996

-Ruddle and Constantini, American geneticists along with Lacy, an American biologist injected DNA into a single-cell mouse embryo using the methods developed by Brinster in the 1960s/1970's (32)
-This produced genetically modified mice which had its genome altered through the use of genetic engineering techniques.(32)
-These mice are commonly used as animal models of human diseases.They have been used to study obesity, heart disease, diabetes, substance abuse, anxiety, Parkinson disease and cancer.(32)
Frank Ruddle, Frank Constantini and Elizabeth Lacy 1981
-Reiji Okazaki was a Japanese molecular biologist.His scientific career was cut short and he died of cancer in 1975 at the age of 44, this was perhaps related to the atomic bombing in WW2 in Hiroshima, Japan.(33)
-Okazaki proposed there were three possibilities for replicating a double-stranded DNA molecule.(33)
-He concluded that DNA replication was a discontinuous mechanism. He used a mutant deficient in a repair process and saw that there were fragments produced by this repair. The small fragments were called Okazaki fragments in his honor.(33)
Reiji Okazaki 1966
The End!
-Archibald Garrod was a British physician who connected human disorders with Mendel's laws of inheritance. (34)
-He proposed the idea that diseases was a metabolic route and that hereditary diseases, were caused by inborn errors of metabolism on the basis of inheritance.(35)
- Garrod's biochemical role to genes laid the groundwork for other discoveries linked to genetics. (34)
Archibald Garrod 1908
Sydney Brenner 2002
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