copyright cmassengale DNA and Replication copyright cmassengale
copyright cmassengale History of DNA Chromosomes are made of both DNA and protein Radioactive 32P was injected into bacteria! copyright cmassengale
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
copyright cmassengale Chargaff’s Rule __________________ must pair with __________________ The bases form weak _______________________________ T A G C copyright cmassengale
copyright cmassengale 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
copyright cmassengale Rosalind Franklin copyright cmassengale
copyright cmassengale DNA Structure copyright cmassengale
copyright cmassengale 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
copyright cmassengale DNA Double Helix __________________________ “Rungs of ladder” “Legs of ladder” __________________________ copyright cmassengale
copyright cmassengale 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
copyright cmassengale DNA Stands for ______________________________________ Made up of subunits called ______________________________________ Nucleotide made of: 1. _____________________________ 2. _____________________________ 3. _____________________________ copyright cmassengale
copyright cmassengale 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
copyright cmassengale Pentose Sugar Carbons are numbered clockwise 1’ to 5’ CH2 O C1 C4 C3 C2 5 Sugar (deoxyribose) copyright cmassengale
copyright cmassengale DNA P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A copyright cmassengale
copyright cmassengale 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
copyright cmassengale Nitrogenous Bases Double ring PURINES Adenine (A) Guanine (G) Single ring PYRIMIDINES Thymine (T) Cytosine (C) A or G T or C copyright cmassengale
copyright cmassengale Base-Pairings Purines only pair with Pyrimidines Three hydrogen bonds required to bond Guanine & Cytosine C G 3 H-bonds copyright cmassengale
Two hydrogen bonds are required to bond Adenine & Thymine copyright cmassengale
copyright cmassengale Question: If there is 30% Adenine, how much Cytosine is present? copyright cmassengale