DNA and Genetics

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• Chapter 1 - Science Dimensions  10

1. Deoxyribonucleic Acid (DNA)
   1. Molecule Structure

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      • Refer to Figures 1.1.1 to 1.1.5
      1. The same structure in all living things
      2. Twisted ladder shape

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         • Figure 1.1.2
      3. Made up of nucleotides
         1. Nucleotide structure

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            • Nucleotides are made up of a deoxyribose sugar component, phosphate component and a base component (adenine, thymine, guanine or cytosine).
            • Figure 1.1.1
      4. Rung details

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         • The rungs (really called complementary base pairs) are pairs of nitrogen rich bases. There are four types of bases: Adenine (A), Thymine (T), Guanine (G) and Cytosine (C).
         • Of the four bases, only two pairs can be made - AT is one, and CG is the other.
         1. Only sugar components can connect to rungs
         2. Genetic code is the order of the bases
   2. Genes and chromosomes
      1. Genes
         1. Found in DNA
      2. Chromosomes
         1. Two DNA strands and protein
         2. Each human cell has 46
   3. Discovered in 1869
   4. Replication and Cell Division
      1. Cell Division
         1. Meiosis
            1. Involved in creating new life
         2. Mitosis
            1. Involved in growth and repair
      2. Cells replicate to create organisms