DNA basics 3.0 / 5 based on 1 rating ? BiologyDNA, genetics and evolutionASAQA Created by: TomCreated on: 08-05-13 20:02 what makes DNA DNA is a polynucleotide - its made up of lots of nucleotides joined together each nucleotide is made from a pentose sugar (with 5 carbon atoms) a phosphate group and a nitrogen base the sugar in DNA nucleotides is a deoxyribose sugar each nucleotide has the same sugar and phosphate. the base on each nucleotide can vary through. there are four possible bases - adenine (A), thymine (T), cystosine (C) and Guanine (G) 1 of 2 what forms a double helix DNA nucleotides join together to form poly-nucleotide strands the nucleotide join up between the phosphate group of one nucleotide and the sugar of another, creating a sugar-phosphate backbone two DNA polynucleotide strands join together by hydrogen bonds between bases each base can only join with one particular partner - this is called specific base pairing adenine always pairs with thymine (A - T) and guanine always pairs with cytosine (G - C) the two strands wind up to form the DNA double-helix 2 of 2
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