DNA Web Search
5.23.12
In 1869, a Swiss doctor, Friedrich Miescher, isolated a new chemical substance. Miescher was interested in cells, which were visible through a new invention, the microscope. As a doctor, Miescher had a ready supply of white blood cells, from the pus-filled bandages at the hospital where he worked. Miescher added some simple chemicals to these cells and isolated a white precipitate he called "nuclein." Miescher assumed, correctly, that the precipitate was from the large nuclei of the white blood cells. Although not recognized at the time, Miescher had isolated the first crude extract of DNA.
After Miescher’s discovery, other scientists found better ways to purify the new substance. Nuclein was a crude extract and contained a lot of proteins. Once the proteins were removed, the "pure" substance became known as deoxyribonucleic acid because of its sugar structure (ribose-based) and its properties (acidic nature).
Scientists, such as Phoebus Levene, began deconstructing the DNA components. They found that DNA was essentially a long-chain molecule, made up of four different nucleotides, ribose sugar, and phosphate.Was DNA really the stuff of life? How could something that essentially had only four different components (the nucleotides) really contain all the information necessary for the form and function of life?Many scientists believed that DNA was too simple a molecule to be the template for life. Proteins with their 20 different amino acid building blocks would have many more combinatorial possibilities.Protein or DNA? Which is the hereditary molecule? In the early part of the 20th century, there were proponents in both camps. This all changed in 1944 when Oswald Avery published his results. In a very simple experiment, Oswald Avery's group showed that DNA was the "transforming principle." When isolated from one strain of bacteria, DNA was able to transform another strain and confer characteristics onto that second strain. DNA was carrying hereditary information.With DNA as the hereditary molecule, the stage was set for one of the most exciting periods in DNA science: understanding DNA structure and function.
1. What types of cells did Fredrich Miescher work with?
He worked with white blood cells.
2. From where did he get the nuclein?
He got it from the white blood cells.
3. What do we know nuclein as today?
We call nuclein DNA.
4. What contribution did Phoebus Levene make towards the discovery of DNA's structure?
He began deconstructing the DNA components.
5. Why were more scientists in the 1920's through the early 1940's skeptical that DNA was the molecule of life?
Many scientists believed that DNA was too simple a molecule to be the template for life.
6. Why was Oswald Avery's experiment an important contribution towards the discovery of DNA's structure?
His work showed that the DNA wasthe "transforming principle".
After Miescher’s discovery, other scientists found better ways to purify the new substance. Nuclein was a crude extract and contained a lot of proteins. Once the proteins were removed, the "pure" substance became known as deoxyribonucleic acid because of its sugar structure (ribose-based) and its properties (acidic nature).
Scientists, such as Phoebus Levene, began deconstructing the DNA components. They found that DNA was essentially a long-chain molecule, made up of four different nucleotides, ribose sugar, and phosphate.Was DNA really the stuff of life? How could something that essentially had only four different components (the nucleotides) really contain all the information necessary for the form and function of life?Many scientists believed that DNA was too simple a molecule to be the template for life. Proteins with their 20 different amino acid building blocks would have many more combinatorial possibilities.Protein or DNA? Which is the hereditary molecule? In the early part of the 20th century, there were proponents in both camps. This all changed in 1944 when Oswald Avery published his results. In a very simple experiment, Oswald Avery's group showed that DNA was the "transforming principle." When isolated from one strain of bacteria, DNA was able to transform another strain and confer characteristics onto that second strain. DNA was carrying hereditary information.With DNA as the hereditary molecule, the stage was set for one of the most exciting periods in DNA science: understanding DNA structure and function.
1. What types of cells did Fredrich Miescher work with?
He worked with white blood cells.
2. From where did he get the nuclein?
He got it from the white blood cells.
3. What do we know nuclein as today?
We call nuclein DNA.
4. What contribution did Phoebus Levene make towards the discovery of DNA's structure?
He began deconstructing the DNA components.
5. Why were more scientists in the 1920's through the early 1940's skeptical that DNA was the molecule of life?
Many scientists believed that DNA was too simple a molecule to be the template for life.
6. Why was Oswald Avery's experiment an important contribution towards the discovery of DNA's structure?
His work showed that the DNA wasthe "transforming principle".