07 Molecular Genetics

07 Molecular Genetics - Click to edit Master subtitle style...

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Unformatted text preview: Click to edit Master subtitle style 1/18/11 Molecular Genetics Molecular Genetics Molecular Genetics 1/18/11 Molecular Genetics Molecular Genetics In eukaryotes, chromosomes bear the genetic information that is passed from parents to offspring The genetic information is stored in molecules of DNA The DNA codes for enzymes, which, in turn, regulate chemical reactions that direct metabolism for cell development, growth, and maintenance Animation: DNA Double Helix Molecular Genetics 1/18/11 Molecular Genetics Molecular Genetics As a review, DNA and RNA are polymers of nucleotides The nucleotide monomer consists of 3 parts 1. Nitrogen Base 2. Sugar 3. Phosphate Group Review figure 8-1 Animation: DNA and RNA Structure Molecular Genetics 1/18/11 Molecular Genetics DNA Replication During interphase of the cell cycle, a second chromatid containing a copy of DNA molecule is assembled The process, called DNA replication , involves separating (unzipping) the DNA molecule into two strands, each of which serves as a template to assemble a new, complementary strand Molecular Genetics 1/18/11 Molecular Genetics DNA Replication The result is two identical double-stranded molecules of DNA Because each of these double-stranded molecules of DNA consists of a single strand of old DNA (the template strand) and a single strand of new, replicated DNA (the complementary strand), the process is called semiconservation replication Review figure 8-2 Molecular Genetics 1/18/11 Molecular Genetics DNA Replication During DNA replication, the enzyme helicase unwinds the DNA helix, forming a Y-shaped replication fork Single strand binding proteins attach to each strand of the uncoiled DNA to keep them separate As helicase unwinds the DNA, it forces the double-helix in front of it to twist A group of enzymes, called topoisomerases , break and rejoin the double helix, allowing the Molecular Genetics 1/18/11 Molecular Genetics DNA Helicase Molecular Genetics 1/18/11 Molecular Genetics DNA Replication Since a DNA double-helix model consists of 2 opposing DNA strands, the uncoiled DNA consists of a 3’ ¡ 5’ template strand and a 5’ & 3’ template strand v The 3 and the 5 stand for the carbon # on the sugar molecule The enzyme that assembles the new DNA strand, DNA polymerase moves in the 3’ & 5’ direction along each template strand A new (complement) strand grows in an Molecular Genetics 1/18/11 Molecular Genetics DNA Polymerase Molecular Genetics 1/18/11 Molecular Genetics Leading Strand For the 3’ … 5’ template strand, replication occurs continuously as the DNA polymerase follows the replication fork assembling a 5’ S 3’ complementary strand This complementary strand is called the leading strand Molecular Genetics 1/18/11 Molecular Genetics Lagging Strand For the 5’ … 3’ template strand, however, the DNA polymerase moves away from the uncoiling replication fork This is because it can assemble nucleotides...
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07 Molecular Genetics - Click to edit Master subtitle style...

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