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Deoxyribonucleic Acid (DNA)

Deoxyribonucleic Acid (DNA). Ms. Napolitano & Mrs. Haas CP Biology. Contributions to DNA. Oswald Avery – DNA stores & transmits genetic information Alfred Hershey & Martha Chase – genetic material of bacteriophages (type of virus) is DNA, not proteins Erwin Chargaff – base pairing rules

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Deoxyribonucleic Acid (DNA)

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  1. Deoxyribonucleic Acid (DNA) Ms. Napolitano & Mrs. Haas CP Biology

  2. Contributions to DNA • Oswald Avery – DNA stores & transmits genetic information • Alfred Hershey & Martha Chase – genetic material of bacteriophages (type of virus) is DNA, not proteins • Erwin Chargaff – base pairing rules • Rosalind Franklin – DNA is a helical • James Watson & Francis Crick – first DNA model (1953), DNA is double helix

  3. Nucleotides • Basic unit of DNA • 3 components: • 5-carbon sugar (deoxyribose) • Phosphate group • Nitrogenous base

  4. Types of Nitrogenous Bases • Purines– 2 ring structure • Adenine (A) • Guanine (G) • Pyrimidines - 1 ring structure • Thymine (T) • Cytosine (C)

  5. DNA Backbone • DNA backbone = sugar & phosphate groups of each nucleotide bonded together

  6. Base Pairing • Thank you, Chargaff! • Aalways pairs with T • Calways pairs with G

  7. The Double Helix • Thank you, Franklin, Watson, & Crick! • Looks like a twisted ladder

  8. DNA Coiling  Chromosomes • Chromatin – tightly coiled DNA around proteins called histones • Chromatin condenses even more during mitosis to make chromosomes

  9. DNA Replication • Complementary strands – one strand can be used to make the other strand • Replication - duplicating DNA • Happens during the S phase (remember that?!) • Occurs at replication forks • DNA splits into 2 strands, which produce 2 new complementary strands • Follows rules of base pairing • Each strand is a DNA template for the new strand

  10. Important Enzymes • Helicase – unzips DNA strand • DNA polymerase – 2 functions • Joins nucleotides to the original DNA strand • Proofreads for errors

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