Presentation on theme: "Structure and Composition"— Presentation transcript:
1 Structure and Composition DNA is sometimes called "the blueprint of life" because it contains the code, or instructions for building and organizing and ensuring that organism functions correctly.
2 DeoxyriboNucleic Acid DNA is composed of subunits called nucleotides, strung together in a long chainEach nucleotide consists of: a phosphate, a sugar (deoxyribose), and a base
3 Bases Bases come in two types: pyrimidines (cytosine and thymine) and purines(guanine and adenine)
4 The sugar and phosphates make up the "backbone" of the DNA molecule.
5 The rungs of the ladder are composed of nucleotides. The shape of the DNA molecule is a double-stranded helix (like a twisted ladder).The sides of the ladder are composed of alternating sugars (deoxyribose) and phosphates.The rungs of the ladder are composed of nucleotides.James Watson & Francis Crick
6 Base Pair RuleNucleotides pair in a specific way - called the Base-Pair RuleAdenine always pairswith Thymine (A-T)Guanine always pairswith Cytosine (C-G)