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Published byHengki Pranata Modified over 5 years ago
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DNA and Replication copyright cmassengale
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History of DNA Chromosomes are made of both DNA and protein Radioactive 32P was injected into bacteria! copyright cmassengale
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Discovery of DNA Structure
Erwin Chargaff showed the amounts of the four bases on DNA ( A,T,C,G) In a body or somatic cell: __________ = 30.3% __________ = 19.5% __________ = 19.9% copyright cmassengale
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Chargaff’s Rule __________________ must pair with __________________ The bases form weak _______________________________ T A G C copyright cmassengale
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DNA Structure _____________________took diffraction x- ray photographs of DNA crystals In the 1950’s, ____________________________________ ____________________________________ built the first model of DNA using Franklin’s x-rays copyright cmassengale
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Rosalind Franklin copyright cmassengale
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DNA Structure copyright cmassengale
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DNA Two strands coiled called a _________________ Sides made of a pentose sugar __________________bonded to phosphate (PO4) groups by phosphodiester bonds Center made of _______________________________________ _______________________________________ bonded together by weak ___________________ copyright cmassengale
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DNA Double Helix __________________________ “Rungs of ladder” “Legs of ladder” __________________________ copyright cmassengale
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Helix Most DNA has a ___________________________________ twist with 10 base pairs in a complete turn Left twisted DNA is called Z-DNA or southpaw DNA Hot spots occur where right and left twisted DNA meet producing _____________________________________ copyright cmassengale
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DNA Stands for ______________________________________ Made up of subunits called ______________________________________ Nucleotide made of: 1. _____________________________ 2. _____________________________ 3. _____________________________ copyright cmassengale
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DNA Nucleotide O=P-O O Phosphate Group N Nitrogenous base (A, G, C, or T) O CH2 O C1 C4 C3 C2 5 Sugar (deoxyribose) copyright cmassengale
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Pentose Sugar Carbons are numbered clockwise 1’ to 5’ CH2 O C1 C4 C3 C2 5 Sugar (deoxyribose) copyright cmassengale
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DNA P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A copyright cmassengale
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Antiparallel Strands One strand of DNA goes from 5’ to 3’ (sugars) The other strand is opposite in direction going 3’ to 5’ (sugars) copyright cmassengale
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Nitrogenous Bases Double ring PURINES Adenine (A) Guanine (G) Single ring PYRIMIDINES Thymine (T) Cytosine (C) A or G T or C copyright cmassengale
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Base-Pairings Purines only pair with Pyrimidines Three hydrogen bonds required to bond Guanine & Cytosine C G 3 H-bonds copyright cmassengale
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Two hydrogen bonds are required to bond Adenine & Thymine
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Question: If there is 30% Adenine, how much Cytosine is present? copyright cmassengale
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