biol 9 through 13

biol 9 through 13 - Oct. 10 Chapter 9: DNA: The Molecule of...

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Unformatted text preview: Oct. 10 Chapter 9: DNA: The Molecule of Heredity How Did Scientists Discover That Genes Are Made of DNA? Griffith Discovers Transformation: Figure 9-1 He was trying to make a vaccine for pneumonia Living R (rouge) strain not virulent mice lived were able to get rid of strain Living S (smooth) strain virulent mice died couldnt get rid of strain Killed S strain mice lived once dead, strain didnt multiply Living R strain and killed S strain mice dead blood teeming with living s strain bacteria Avery, MacLeod, and McCarty: What is the transforming material? Cell extracts treated with protein, carbohydrate, and RNA digesting enzymes could still transform bacteria Cells extracts treated with DNA digesting enzyme lost their transforming ability Concluded that DNA transform bacteria What is the Structure of DNA? Nucleotide Bases in DNA: Each nucleotide has a phosphate, deoxyribose sugar, and N-containing base (pg 151) Four types of nucleotide in DNA: Thymine Adenine Cytosine Guanine A Nucleotide Stand: Nucleotide stands are always assembled from the P end to the S end Covalent bond b/n the sugar of one of the nucleotide and the phosphate of a second. P (phosphate end) S (sugar end) The Watson-Crick Model of DNA Structure: DNA is a double helix of 2 nucleotide strands Complementary base pairs hold the 2 nucleotide strands together Complementary strands run in opposite directions (parallel) Base Pairing in DNA: Chargaffs rule: The amount of A always =T The amount of C always =G Adenine & Thymine always form pairs 2 hydrogen bonds Cytosine & Guanine always form pairs 3 hydrogen bonds X-ray Diffraction of DNA: Maurice Wilkins and Rosalind Franklin know that DNA forms some sort of helix by the patterns seen in X-ray diffraction The Discovery of DNA: Pauling Wilkins & Franklin Watson & Crick Genetic Code: Along a single DNA strand Order of nucleotides determines order of amino acids in proteins DNA Can Encode A Lot of Information: The order of nucleotides in a single DNA strand can encode a large amount of data Computers: 0 & 1 codes for everything DNA: A, T, C, & G codes for everything DNA stand 10 nucleotides long has 4 10 different possible combinations or 1,048,576 Some humans chromosomes are 250,000,000 nucleotides long; 4 250,000,000 possible combinations How Does DNA Replication Ensure Genetic Constancy? DNA Structure Helps Explain How It Duplicates: DNA is two nucleotides stands held together by hydrogen bonds Hydrogen bonds between two strands are easily broken Each new strand then serves as a template for new strand DNA Replication: Separation of parental DNA helix Incorporation of complementary nucleotides 2 daughter helices 1 old stands 1 new strand Figure 9-4 The Semi-conservative Replication Model:...
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This note was uploaded on 04/28/2008 for the course BIOL 1001 taught by Professor Minor during the Fall '08 term at LSU.

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biol 9 through 13 - Oct. 10 Chapter 9: DNA: The Molecule of...

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