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8: DNA Replication

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    Chapter 8 BSC 3271 Learning Outcomes

    • Describe the structure of DNA, including antiparallel strands, nucleotide structure (arrangement of three components), base-pair rule, bonding and composition of “backbone”, and bonding between bases in “rungs”.
    • Sketch the structure of a DNA nucleotide, labeling the phosphate, deoxyribose, and nitrogenous base (don't need detailed structure); indicate what functional group is bound  to the 3' and 5' carbons of the deoxyribose
    • Given a diagram of a DNA molecule, identify: phosphate, deoxyribose, purine, pyrimidine, hydrogen bonds, phosphodiester bond, 5' end, 3' end
    • Describe the structure of bacterial chromosomes and plasmids and the kind of information they carry.
    • Explain the purpose of DNA replication in a cell
    • Explain the process of DNA  replication, including the roles of the enzymes primase, helicase, DNA polymerase, and ligase, the direction of replication, and the meaning of  semi-conservative replication.
    • Given a diagram of replicating DNA, determine the sequence of the newly synthesized strand(s) and which strand is the leading strand and which is the lagging strand.
    • Explain why both strands of the DNA molecule can’t be synthesized continuously and define Okazaki  fragments.

    • 8.1: The Structure and Function of Cellular Genomes
      The entire genetic content of a cell is its genome. Genes code for proteins, or stable RNA molecules, each of which carries out a specific function in the cell. Although the genotype that a cell possesses remains constant, expression of genes is dependent on environmental conditions. A phenotype is the observable characteristics of a cell (or organism) at a given point in time and results from the complement of genes currently being used.
    • 8.2: Structure and Function of DNA
      Nucleic acids are composed of nucleotides, each of which contains a pentose sugar, a phosphate group, and a nitrogenous base. Deoxyribonucleotides within DNA contain deoxyribose as the pentose sugar. DNA contains the pyrimidines cytosine and thymine, and the purines adenine and guanine. Nucleotides are linked together by phosphodiester bonds between the 5ʹ phosphate group of one nucleotide and the 3ʹ hydroxyl group of another.
    • 8.3: DNA Replication
      The DNA replication process is semiconservative, which results in two DNA molecules, each having one parental strand of DNA and one newly synthesized strand. In bacteria, the initiation of replication occurs at the origin of replication, where supercoiled DNA is unwound by DNA gyrase, made single-stranded by helicase, and bound by single-stranded binding protein to maintain its single-stranded state.

    Thumbnail: adapted from "File:Bidirectional DNA replication in Bacteria.png" by Bootan68 is licensed under CC BY-SA 3.0