Genetics213-1stTestNotes - Chapter 6 DNA is...

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Chapter 6 DNA is deoxyribonucleic acid -sugar known as deoxyribose, found mainly in cell nuclei, acidic -composed of four different subunits (compounds known as nucleotides, which are joined by phosphodiester bonds in linked chains repeating – polymers) Difference between bacterial and eukaryotic genomes! Griffith distinguished between smooth and rough bacterial forms, and used this to show how genetic information can pass form dead to live cells Transformation- the ability of a substance to change the genetic characteristics of an organism Avery went further in showing that this transforming principle was DNA -when he destroyed DNA in the dead S strain, there was no longer a transformation Hershey and Chase assessed the importance of DNA and protein in gene transmission by infecting bacterial cells with viruses (bacteriophages) -basically saw that DNA could be found inside infected cells, where as the labeled protein was still found in the viruses DNA’s three-dimensional structure: nucleotide building blocks (subunits) are linked together in a polynucleotide chain, two chains associate to form a double helix -each nucleotide consists of a deoxyribose sugar, a phosphate, and a nitrogenous base Their chemical compositions, how they come together structurally is depicted on pg.174 -must take into account whether there is a purine (A or G) nucleotide base, or a pyrimidine (T or C) nucleotide base Also see how nucleotides are linked in a directional chain *need to be able to draw these out – difference between showing structure of separate nucleotides and the base pairing between two complementary nucleotides DNA chain, through polarity, always moves in a 5’-to-3’ direction (left to right) -hydrogen bonds that connect pairing groups, present in base pairing…holds the two antiparallel chains of the double helix that associate by complementary base pairing Chargoff ratios – A to T and G to C (complementary base pairing here with H-bonds) Most DNA follows this structure predicted by Watson and Crick -spirals to the right, B-form DNA molecules -some DNA molecules, rare, however have the Z-form where spiral to the left (backbone of molecule has a zig-zag shape) Asking the questions: How DNA’s structure enables it to carry genetic information, replicate that information, and reorganize the information through recombination? Proteins read the information in DNA and carry out its instructions by binding to a
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This note was uploaded on 04/07/2008 for the course BIO 213 taught by Professor Byrne during the Fall '07 term at Wake Forest.

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Genetics213-1stTestNotes - Chapter 6 DNA is...

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