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Published byAlexia Berry Modified over 8 years ago
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DNA
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DNA Deoxyribose Nucleic Acid DNA is a heredity molecule –passed on from parent/s –generation to generation Stores and transmits genetic information Tells the cells which proteins to make DNA RNA Amino Acid Protein Trait
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History of DNA 1920s Erwin Chargaff figured out that the nitrogen bases existed in pairs
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History of DNA Rosalind Franklin took x-ray diffraction photographs of DNA crystals She was first to truly figure out the shape of DNA
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History of DNA James Watson and Francis Crick created “model” of DNA –Double Helix –Twisted Ladder –2 sides
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The Double Helix Made of repeating units of NUCLEOTIDES(monomer of DNA) Sugar, phosphate, and nitrogen base Nucleotides held together by covalent bonds (strong) Backbone (the two sides): alternating SUGAR and PHOSPHATE Sugar is Deoxyribose Center “rungs” : two nitrogen bases connected by a hydrogen bond (weak)
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Nitrogen Bases –Adenine (A) –Guanine (G) –Cytosine (C) –Thymine (T) Complementary Base Pairing Base-pairing rules –Cytosine bonds with Guanine: C-G –Adenine bonds with Thymine: A-T
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Why are organisms different? Base Sequence (order of nitrogen bases) are different for every organism The more similar the physical traits then the more similar the DNA sequencing
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Pass out picture!
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Types of Nitrogen Bases Classified by their “ring” shape Purines –Double ring shape –Adenine and Guanine Pyrimidines –Single ring shape –Cytosine and Thymine
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Purine “pairs” with a pyrimidine. A – T C - G
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