Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in...
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![Page 1: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/1.jpg)
Biologists on Genetics Erwin Chargaff
(1905-2001)
Relative quantities of the nitrogen bases found in DNA
![Page 2: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/2.jpg)
Background
![Page 3: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/3.jpg)
About Erwin Chargaff
Born in Austria on August 11, 1905 Receive a doctorate degree of Chemistry
from the University of Vienna in 1928 1944 - Study of DNA and its four chemical
bases - adenine, cytosine, guanine and thymine
Using chromatography technique Discover amounts of adenine and thymine
were equal, as were the amounts of cytosine and guanine
![Page 4: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/4.jpg)
The 4 nitrogen bases
![Page 5: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/5.jpg)
The 4 nitrogen bases - Purines Consist of a six-membered and a five-membered nitrogen-containing ring, fused together
Adenine = 6-amino purine
Guanine = 2-amino-6-oxy purine
![Page 6: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/6.jpg)
The 4 nitrogen bases - Pyrimidines
Have only a six-membered nitrogen-containing ring
Uracil = 2,4-dioxy pyrimidine
Thymine = 2,4-dioxy-5-methyl pyrimidine
Cytosine = 2-oxy-4-amino pyrimidine
![Page 7: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/7.jpg)
Chargaff's first parity rule
Stated that purines pair with pyrimidines, specifically A with T and C with G
E.g ACGATGCCGTA
With pairing between complementary bases in the "top" and "bottom" strands
![Page 8: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/8.jpg)
Chargaff's second parity rule
% of A approximately equals % of T; % of G approximately equals % of C for single strands of DNA
![Page 9: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/9.jpg)
Cluster rule
Stated that pyrimidines often occur in runs or clusters, and hence on the complementary strand purines do likewise
![Page 10: Biologists on Genetics Erwin Chargaff (1905-2001) Relative quantities of the nitrogen bases found in DNA.](https://reader036.fdocuments.us/reader036/viewer/2022083004/56649ed95503460f94be7da3/html5/thumbnails/10.jpg)
GC rule
Stated that (G+C)% is constant within a species, but often differs between species.