Ch. 18

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Ch. 18
2011-03-13 16:18:54

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  1. Who discovered DNA?
    Johann Miescher
  2. What is Chargaff's rule?
    A+G=C+T (The number of purines is equal to the number of pyrimidines)
  3. What does Topoisomoerase I do?
    Induce DNA relaxation by cutting ONE strand of the double helix, allowing the DNA to rotate and the uncut strand to be passed through the break before the broken strand is released.
  4. What does Topoisomerase II (DNA gyrase) do?
    Induces relaxation by cutting BOTH DNA strands and then passing a segment of uncut double helix through the the break before resealing. Requires energy from hydrolysis of ATP unlike Top. 1
  5. What is the DNA melting temperature?
    Tm, the temperature at which one-half of the absorbance change has been achieved.
  6. What is nucleic acid hybridization?
    A family of techniques in which single-stranded nucleic acids are allowed to bind to each other by complementary base pairings; used for assessing whether two nucleic acids contain similar base sequences.
  7. What is a restriction enzyme?
    Proteins isolated from bacteria that cut foreign DNA molecules at specific internal sites.
  8. What is EcoRI?
    Restriction enzyme. Makes a staggered cut.
  9. What is HaeIII?
    Restriction enzyme
  10. What are single nucleotide polymorphisms (SNPs)?
    Variations in DNA base sequence involving single base changes that occur among individuals of the same species.
  11. Difference between interspersed repeated DNA and tandemly repeated DNA.
    Tandemly repeated DNA is repeated DNA sequences whose multiple copies are adjacent to one another, while interspersed repeated DNA is repeated DNA sequences whose multiple copies are scattered throughout the genome.
  12. What are telomeres?
    DNA sequences located at the ends of chromosomes.
  13. Do prokaryotic genomes have repeating or nonrepeating DNA?
    Nonrepeating DNA
  14. What are transposable elements (transposons)?
    known as jumping gnes because they move around the genome and leave copies of themselves wherever they stop.
  15. What are histones?
    a group of relatively small proteins whose high content of amino acids lysine and arginine gives them a strong positive charge; an octomer of histones forms the core of a nucleosome
  16. What is a nucleosome?
    basic structural unit of eukaryotic chromosome, consisting of about 200 base pairs of DNA associated with an ocotmer of histones.