Summary - DNA and DNA Extraction

  • DNA is a non-living stable molecule. The DNA code is universal allowing it to work the same in all living things. This is a critical fact that makes genetic engineering possible.
  • DNA
    1. DNA is composed of nucleotides bonded to a sugar-phosphate backbone. Double stranded DNA forms a double helix structure.
    2. The DNA double helix coils up into compact structures called chromosomes. Small segments of the chromosome that encode a single protein are called genes.
    3. Chromosomes are microscopic. There are thousands of genes on each chromosome and hundreds of nucleotides in the DNA sequence of each gene.
    4. The role of DNA is to store and pass on genetic information.
  • Proteins
    1. Proteins are chains of amino acids bonded together and folded into a 3-dimensional structure.
    2. Proteins do the ’work’ in a cell and function in 3 ways:
      1. Enzyme=catalyze reactions
      2. Structure=influence cell shape and tissues
      3. Regulate=regulate the expression of other genes
  • Protein Production
    1. DNA in the nucleus is copied by RNA polymerase which reads the code and makes a complimentary copy called RNA. (transcription)
    2. RNA travels from the nucleus to the cytoplasm where amino acids are located.
    3. The RNA code is read by a ribosome 3 nucleotides (1 codon) at a time linking the appropriate amino acids together into a chain. (translation)
    4. The amino acid chain (protein) folds up into a 3-dimensional structure able to perform its function in the cell.
  • DNA extraction is necessary because genetic engineers need to be able to work with the DNA, cut it, locate and clone a single gene, and modify the gene before they insert it into another organism. The steps in DNA extraction are:
    1. Plant tissue is crushed to break open the cells and release the DNA.
    2. Buffered salt solution is added into which the DNA easily dissolves.
    3. Organic solution is added into which other molecules, such as proteins and fats, easily dissolve purifying the DNA solution.
    4. The purified DNA solution is separated from the organic waste solution.
    5. Alcohol is added to the DNA solution causing the DNA to precipitate out into a solid string that can be spooled out with a glass hook and stored indefinitely.