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Published byCorey Carson Modified over 9 years ago
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Deoxyribo- nucleic Acid is made up of nucleotides
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Nucleotides have 3 parts › Deoxyribose (sugar) › Phosphate group › Nitrogenous base
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Deoxyribose and Phosphate are in all nucleotides, but there are 4 different nitrogenous bases › Adenine › Guanine › Cytosine › Thymine
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All nitrogenous bases contain rings Adenine and Guanine contain 2 rings and are called Purines Cytosine and Thymine contain 1 ring and are called Pyrimidines Remember the phrase: › Pure As Gold
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In 1953, Scientists Watson and Crick made a model of DNA as a double helix – the spiral staircase shape. When untwisted looks like a ladder The sides of the ladder are the backbone and alternate with deoxyribose and phosphate
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The bases bond the two strands in the middle A purine always bonds with a pyrimidine so the length is the same They are bonded together by hydrogen bonds
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Cytosine always bonds with Guanine › Hint: (C and G are letters that look alike) Adenine always bonds with Thyamine › Hint: (A and T are letters made of straight lines)
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The order and sequence of these bases is what makes each of us different from one another and different from other species
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