What is DNA? What do the letters stand for? What is it composed of? Where is it found? What is it shaped like? Answer in full sentences. It is the genetic material that can be passed on from parent to offspring DNA –> Deoxyribonucleic acid
It composed of Deoxyribose (5 carbon sugar), a phosphate and a Nitrogonous base (the 4 N-bases are Guanine, Cytosine, Adenine and Thymine) It is a double helix (looks like a twisted ladder.)
DNA is found in the nucleus of most cells
Go to www.dnai.org > Timeline
Visit the above website, read a scientist’s biography, watch an interview, or work through an experiment to identify scientists, dates, events, and facts that makeup the major advances (so far) in the science of DNA. List the answer in front of each question below:
1. Johann Gregor Mendel__________
It took him eight years and more than 10,000 pea plants to discover the laws of inheritance.
2. ___ Linus Pauling_______
Even though he added an extra strand to the structure of DNA, he ultimately won two Nobel Prizes: the Nobel Prize in Chemistry and the Nobel Peace Prize.
3. _____ Martha Chase and Alfred Hershey
These two scientists used a common kitchen appliance to help show that phage DNA carries instructions to make new viruses.
4. ____ Barbara McClintock______
Next time you’re munching away at the movies, think of this Nobel-Prize winning scientist who figured out the process of transposition in corn chromosomes.
5. _____ 1962_____
When did Watson, Crick, and Wilkins win the Nobel Prize in Physiology or Medicine for their model of the structure of DNA?
6. _____ David Baltimore_____
This scientist found that some viruses have an RNA-dependent DNA polymerase that was later named “reverse transcriptase.” He was one of three who shared in the 1975 Nobel Prize in Physiology or Medicine.
7. _____ The Human Genome Project_____
J. Craig Venter’s company, Celera Genomics, worked on this very important project.
8. ____ Density gradient centrifugation______
Matthew Meselson and Frank Stahl invented this new technique in their quest to prove that DNA replication is semi-conservative.
9. _____ Friedrich Miescher_____
I first isolated DNA using pus collected from bandages at a local hospital. Since white blood cells are a major component of pus, they were my source of DNA. Yuck!
10. _____ Thomas Hunt Morgan_____
The “fly room” at Columbia University was established through my efforts. Imagine working in a room filled with bottle after bottle of fruit flies!
11. ____ Thomas R. Cech______
I showed that RNA could act as its own catalyst. Because of my work, it is no longer correct to state, “all enzymes are proteins”.
Go to www.dnai.org > Code > Finding the Structure > problem As you work through the problem section, write, in your own words, the specific contribution that each scientist made to the DNA story in the spaces provided below.
He is famous for discovery of nucleic acid, which led to the discovery of DNA. This occurred while he was studying proteins in leukocytes. He named it ‘nucleic acid’ because it came from the nucleus of the cell.
In 1909 Levene found that the carbohydrate present in yeast nucleic acid is the pentose sugar ribose he succeeded in identifying the carbohydrate in thymus nucleic acid. Levene had succeeded in establishing the nucleic acids as genuine molecules existing independently of the proteins
He discovered that DNA is the material of which genes and chromosomes are made. Go to www.dnai.org > Code > Finding the Structure > players View and listen to the videos and read the text at the site listed above. Write, in your own words, the specific contribution that each scientist made to the DNA story in the spaces provided below.
found out the structure of DNA (the double helix).
Chargaff discovered two rules that helped lead to the discovery of the double helix structure of DNA
Took x-ray of DNA. DNA crystallography allowed Crick to look at the picture to determine it
Linus Pauling contributed a triple-stranded DNA model to scientific research in 1953.
He made discoveries about the molecular structure of nucleic acids and their significance for information transfer in living material.
discovery of the molecular structure of deoxyribonucleic acid — DNA — the building block of all life
Answer the following questions, referring back to the materials you viewed above: 1. Watson and Crick knew that the triple helix model of DNA that Linus Pauling had proposed was incorrect. What evidence did they have for such a conclusion? The problem of replication could not be worked out in triple helix.
2. The work of Rosalind Franklin provided a key piece of data for Watson and Crick’s model of DNA. Summarize that evidence and how it was pivotal to the correct model being built. Rosalind Franklin provided x-ray crystallography photographs that showed a triple helix did not work.