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DNA Structure

Unit 4 – Part 1. DNA Structure. DNA Facts. DNA D eoxyribo N ucleic A cid Basis for all living things Foundation for all diversity & unity on Earth Every living thing has DNA. That means that you have something in common with a zebra, a tree, a mushroom and a beetle!!!!

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DNA Structure

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  1. Unit 4 – Part 1 DNA Structure

  2. DNA Facts • DNA • DeoxyriboNucleicAcid • Basis for all living things • Foundation for all diversity & unity on Earth • Every living thing has DNA. That means that you have something in common with a zebra, a tree, a mushroom and a beetle!!!! • DNA is too small to see, but under a microscope it looks like a twisted up ladder!

  3. History of DNA • Frederick Griffith • Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928) • Rosalind Franklin • X-ray photo of DNA. (1952) • Watson and Crick • described the DNA molecule from Franklin’s X-ray.(1953)

  4. Structure of DNA • Nucleotide • Small units that link together to form DNA • Made of 3 parts • Phosphate Group • 5-C sugar molecule • deoxyribose • Nitrogen Base

  5. Structure of DNA cntd. • Nitrogen (N) base • N base makes nucleotides different • 4 bases • Adenine (A) • Guanine (G) • Thymine (T) • Cytosine (C) • 2 main groups of bases • Purines • Double ring of C & N atoms • Includes adenine and guanine • Pyrimidines • Single ring of C & N atoms • Includes thymine and cytosine • Base pairing rules • Purines bind to pyrimidines • Adenine binds to thymine • Guanine binds to cytosine

  6. Structure of DNA cntd. • Double Helix • Model created by James Watson & Francis Crick • Structure of DNA • “spiral staircase” made of 2 strands of nucleotides twisting around a central axis. • Also known as a “twisted ladder” • Sides of ladder are made of alternating sugar and phosphate units held together with a strong covalent bond • Rungs are made up of a purine and a pyrimidineheld together by a weak Hydrogen (H) bond. • Base pairing results in a complementary strand (this is how DNA replicates)

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