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16 Cards in this Set
- Front
- Back
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Frederich miescher, germany 1819
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Discovered nuclein which is rather like chromatin
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P levene and W jacobs
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discovered that DNA is composed of a sugar, base and a phosphate
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Frederich griffith 1928 transformation experiment
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Wild type ((S) smooth coat could enter cells kill and wasn't killed by the macrophages of the mouse.)
The (R) type lacked the gene for the capsule to protect so it didn't infect and kill the mouse. |
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Frederich griffith 1928 transformation experiment
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The Strained were killed by heat and it's dna was released that DNA could transform avirulent cells to virulent ones by giving them their DNA/Gene so it could make the capsule so it could enter the cell and kill.
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Avery, Macleod, McCarty 1944 protein, RNA, DNA
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Used trypsin to remove the protein - still transformed
Used RNAase to remove RNA - still transformed Used DNAase to remove DNA didn't transform |
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Avery, Macleod, McCarty 1944
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centrifugation - high molecular weight
electrophoresis - high negative charger UV absorption spectrophometry - absorbed at 260nm Analytical chemistry - nitrogen phosphorus ratio is similar to that of DNA |
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Hershey, chase 1952 bacteriophage experiement.
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(phage is composed of DNA and protein only).
sulphur35 for protein phosphorus 32 for DNA was found to contain phosphorus 32. |
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Purines
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Adenine (6-aminopurine)
guanine (2-amino-6-ketopurine) |
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Pyrimidines
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Cytosine ( 2-keto, 4-aminopyrimidine)
Uracil (2,4-ketopyrimidine) Thymine (2,4-keto, 5- methylpyrimidine) |
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OH or phosphate comes off position 3 of Dna and can form phosphodiester bonds
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phosphate comes off position 6 of dna and can form phosphodiester bonds.
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what is chargaff's rules?
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that pyrimidines are always roughly in the same number as purines.
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Franklin x-ray diffraction showed that dna is a repeating, helical structure.
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Spacing between adjacent bands is inversely proportional to the repeat distance.
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Why the double helix?
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to resolve the argument of it being a helix with a regular repeating structure (franklin) yet needing to have an irregular sequency of bases.
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where are the bases,sugars, phosphates?
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sugars and phosphates on the outside and the bases on the inside.
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why does absorbance rise when dna is denatured?
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because the coming together of bases lowers absorbance and when they are free you get the hyperchromic shift.
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GC pairs have 3 hydrogen bonds.
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AT pairs only have 2 hydrogen bonds.
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