EXAM 3 - EXAM 3 17:47 Chapter 9 DNA: The Molecule of...

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Unformatted text preview: EXAM 3 17:47 Chapter 9 DNA: The Molecule of Heredity How Did Scientists Discover That Genes Are Made of DNA? Griffith Discovers Transformation Figure 9-1 Avery, MacLeod & McCarty What is the transforming material? Cell extracts treated with protein, carbohydrate, and RNA digesting enzymes could still transform bacteria Cell extracts treated with DNA-digesting enzymes lost their transforming ability Concluded that DNA transforms bacteria What is the Structure of DNA? Nucleotide Bases in DNA Each nucleotide has a phosphate, deoxyribose sugar, and N-containing base (page 151) A Nucleotide Strand Nucleotide strands are always assembled from the P end to the S end Covalent bond between the sugar of one nucleotide and the phosphate of a second The Watson-Crick Model of DNA Structure DNA is a double helix of 2 nucleotide strands Complementary base pairs hold the 2 nucleotides strands together Complementary strands run in opposite directions Base Pairing in DNA Chargaffs rule A = T C = G Adenine & Thymine always form pairs 2 hydrogen bonds Cytosine & Guanine always form pairs 3 hydrogen bonds THE DNA of an organism has guanine as 30% of its nucleotide bases. What percentage would be adenine? 20% The DNA of an organism has how much THYMINE? What is the complement of this nucleic acid strand? (AGCTG) TCGAC What is the complement of this nucleic acid strand? (P-AGCTG-S) S-TCGAC-P X-ray Diffraction of DNA Maurice Wilkins and Rosalind Franklin knew that DNA formed some sort of helix by the patterns seen in X-ray diffraction Figure 9-2 The Discovery of DNA Pauling Wilkins and Franklin Watson and Crick The correct structure of a nucleotide is ___. Phosphate, 5-carbon sugar, nitrogen base In an analysis of the nucleotide composition of DNA to see which bases are equivalent in concentration, which of the following would be true? A+C=G+T How is the information coding for genes stored in DNA molecule? The order of nucleotides on a single strand 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 strand 10 nucleotides long has 4^10 different possible combinations; 4^10 = 1,048,576 Some human chromosomes are 250,000,000 nucleotides long; 4^250,000,000 possible combinations How Does DNA Replication Ensure Genetic Constancy?...
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This note was uploaded on 10/07/2011 for the course BIOL 1001 taught by Professor Minor during the Fall '08 term at LSU.

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EXAM 3 - EXAM 3 17:47 Chapter 9 DNA: The Molecule of...

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