DNA Structure - • Rosalind Franklin used X-ray...

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DNA Structure nucleic acid - first discovered by Friedrich Miescher P. A. Levene - determined nucleic acids’ basic structure (5-carbon sugar, phosphate group, nitrogenous base) o believed that 4 types of nucleotides available in equal amounts, repeated purine - adenine or guanine pyrimidine - thymine (replaced by uracil in RNA) or cytosine nucleotide - DNA unit, each consists of 5-carbon sugar, phosphate group, base o phosphate/hydroxide groups allow nucleotides to attach in long chains o phosphodiester bond - holds nucleotides together Erwin Chargaff - showed that DNA didn’t just repeat itself o amount of adenine always equals amount of thymine o amount of cytosine always equals amount of guanine 3D shape of DNA - shaped like staircase wrapping around a common axis
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Unformatted text preview: • Rosalind Franklin- used X-ray diffraction to analyze DNA o bombarded DNA w/ X-ray beam, diffraction shows shape of molecule o used DNA fibers to analyze shape o thought that DNA could have helix shape • James Watson/Francis Crick- used Franklin ’s results before she published them o found that DNA made up of 2 chains of nucleotides, forming a double helix • complementarity- sets of hydrogen bonds link together base pairs o adenine forms 2 hydrogen bonds w/ thymine o guanine forms 3 hydrogen bonds w/ cytosine o knowing the sequence of 1 strand gives the sequence of the other strand • antiparallel configuration- 2 strands of DNA oriented in different directions • collective energy from all the base pairs together makes DNA strand very stable...
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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