CB Test2

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CB Test2
2011-02-13 11:44:46
cell bio ch5 ch7

Materials for test 2
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  1. What is the Central Dogma of biology?
    That genetic information flows from DNA to RNA to proteins.
  2. What did Avery, MacLeod, and McCarty do?
    Demonstrated the "transforming principle" was due to DNA.
  3. What year did Watson and Crick receive the Nobel prize and why?
    1962, for discovering the structure of DNA.
  4. What did Griffith do?
    Discovered "transforming principle" - nonpathogenic bacteria would become pathogenic when exposed to dead pathogenic bacteria.
  5. What did Hershey & Chase do?
    "Waring blender" experiment - they tagged a virus with radioactive markers, and were able to determine that DNA entered host bacteria cells, not protein. Clinched the case for DNA carrying heredity.
  6. What did Mendel do?
    Inheritance in pea plants; demonstrated that each parent contributed one unit of heredity for each trait.
  7. Why is a coding region different from a gene?
    A coding region carries only the information needed to produce a protein or RNA molecule and is a subset of a gene.
  8. What is a homolog?
    Homologous chromosome, which is the maternal and paternal pair of chromosomes.
  9. What is the structure of a nucleosome?
    Core histone octomer made up of 2 each of H2A, H2B, H3, and H4 histones (about 10 nm wide), with about 147 DNA bp wrapped around it 1.7 times.
  10. What is the net charge on the histone core?
    Positive, which will attract the negatively charged phosphate groups on the DNA backbone.
  11. What are the steps of condensation in DNA?
    • "beads on a string" - nucleosomes with linker DNA
    • 30-nm fiber - histone H1 binds DNA when it enters & exits each nucleosome
    • 30-nm fiber loops
    • condensed to form interphase chromosome
    • condensed to form mitotic chromosome
  12. What does the chromatin remodeling complex do?
    using ATP hydolysis, it slides nucleosomes down and back to allow access to the wrapped DNA
  13. Explain acetylation.
    an acetyl group will bind to a histone tail, neutralizing the lysine positive charge, causing the DNA to expand which will acllow gene expression. HATs attach the acetyl groups to the histone tails, HDACs remove the acetyl groups.
  14. Explain methylation.
    methyl groupas are attached to the histone tails, tightening the DNA strand, causing gene expression to be repressed. HMTs attach the metyl groups to the istone tails.
  15. What is X-inactivation?
    One X chromosome is put into heterochromatin and repressed during embryogenesis - which X that is chosen is random, and is maintained through subsequent divisions. Result is that female mammals are mosiacs.