DNA Scientists

Scientists

DNA Scientists Notes:

• Frederick Griffith

  • Born on October 3, 1877

  • He was born in England

  • He was a British bacteriologist

  • His experiment of bacterium was the first to reveal the transforming principle which led to the discovery that DNA acts as the carrier of genetic information

  • Died in 1941 in London

  • Discovery:

    • The first to identify or discover the bacterial transformation

  • Experiment:

    • Griffith wondered how bacteria makes people sick.

      • Specifically, how did certain types of bacteria produce pneumonia

    • Isolated 2 similar bacteria from mice

      • 2 different strands of the same bacterial species

        • S Strain- disease-causing bacteria- pneumonia (smooth colonies)

        • R Strain- harmless bacteria (rough edges)

    • Injected mice with disease-causing bacteria, the mice developed pneumonia and died

    • When he injected mice with harmless bacteria, the mice stayed healthy

    • He then ran a series of experiments

• Oswald Avery

  • Avery was born on October 21, 1877

  • He was born in Nova Scotia

  • He was a Canadian-born American bacteriologist

  • His research helped establish that DNA is the substance responsible for heredity (setting the foundation for the new science of molecular genetics)

  • Died on February 20, 1955

  • Discovery:

    • By observing bacterial transformation, Avery and other scientists discovered that the nucleic acid DNA stores and transmits genetic information from one generation of bacteria to the next.

  • Experiment

    • He used enzymes to destroy the proteins for example and injected them into the mouse to see if they had died

    • The scientists were unsure if there were any other Bacterias

• Alfred Hershey and Martha Chase

  • American Scientist

  • They collaborated in studying viruses- tiny, nonliving particles that can infect living cells

  • Helped to confirm genetic information

  • Discovery:

    • Hershey and Chase’s experiment with bacteriophages confirmed Avery’s results, convincing many scientists that DNA was the genetic material found in genes- not just in viruses and bacteria, but in all living cells

  • Experiment:

    • At the end of their experiment, they were the ones who confirmed that DNA was the genetic material

• Erwin Chargaff

  • Australian-American biochemist

  • Chargaff began the research that would later lead to the discovery of the double helix

  • Experiment:

    • Erwin Chargaff wanted to find the exact amount of certain chemicals found in DNA

    • To do this he used paper chromatography to separate the different chemicals found in DNA

    • Chargaff then used UV Spectrophotometry to calculate the exact amounts of Adenine, Thymine, Cytosine, and Guanine

  • Discovery:

    • He discovered that the base pairs A and T are equal to each other and so are C and G

    • Also Known as Chargaff’s rules

• Rosaline Franklin

  • She was a British chemist and X-ray crystallographer

  • She studied the molecule of DNA

  • Discovery:

    • Franklin’s X-ray pattern does not reveal the structure of DNA, but it carries some crucial clues

  • Experiment:

    • She used a technique called X-ray diffraction

    • First she purified a large amount of DNA

    • Then, stretched the DNA fibers in a thin glass tube so that most of the strands were parallel

    • Next, She aimed a x-ray beam at the concentrated DNA samples and recorded the scattering pattern of the x-rays on film

    • These patterns did not reveal the structure of DNA but the clues are

      • The X-Shaped pattern shows that the strands in DNA are twisted around each other like coils of a spring, a shape known as a helix

      • The angle of the X suggests that there are two strands in the structure

      • The Nitrogenous bases are near the center of the DNA molecule

• Maurice Wilkins

  • He was a Physicist

  • British biophysicist whose X-ray diffraction studies of Deoxyribonucleic acid (DNA) proved crucial to the determination of DNA’s molecular stricture

  • Took Rosaline Franklin’s work

  • Discovery:

    • He uncovered the structure of DNA

      • He was involved by giving X-ray diffraction

      • He was also responsible for showing the first crystalline symmetrical patterns of DNA

  • Experiment:

    • He stole the notes of Rosaline Franklin cause he was the head of the group

• Watson and Crick

  • Watson was an American molecular biologist

  • Crick was a British physicist

  • Given full credit for the actual shape from Rosaline’s notes