Genetics 12

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Genetics 12
2012-07-20 12:45:02
Dr Troy Bray

Genetics lecture test number three.
Show Answers:

  1. What is the central Dogma of Genetics?
    DNA replication > Transcription > RNA > Translation > protein
  2. What is a gene?
    Segment of DNA that is used to make a functional product ( RNA or Polypeptide)
  3. What is a structural Gene?
    • Encodes the amino acid sequence of a polypeptide.
    • 90% of all genes.
  4. What is a promoter?
    Seqeunce that specifies a site to begin transcription.
  5. What is a Terminator?
    Sequence that specifies a site to end transcription.
  6. What word describes the relationship of RNA transcript to the DNA template?
    • Antisense
    • Noncoding
    • Complementary
  7. In structural genes the non-template DNA strand is called what?
    • Coding strand
    • Sense strand
  8. What are transcription factors and what are the two types?
    • Proteins that recognize base sequences in DNA and control transcription.
    • Some bind to promoters and initiate transcription.
    • Some bind to regulatary sequences and either increase or decrease the rate of transcription.
  9. Where is the promoter located for a bacterial gene?
    Upstream from the structural gene.
  10. What are Sequence elements?
    Short sequences within promoter regions that are critically important for the recognition of promoters.
  11. Where are the two important sequence elements located in regards to genes in the bacterial chromosomes?
    • -35
    • -10
  12. What is a Pribnow box?
    Sequence element located at the -10 region. 
  13. Consensus precentage is _____ at -35 than it is at the -10 pribnow box.
  14. What are the 5 subunits of RNA polymerase?
    • Alpha : Bind to DNA
    • Beta & beta' : catalyze synthesis of RNA.
    • Omega : assembles the core enzyme.
    • Sigma factor recognizes the promotor sequence.
  15. What word can be used to describe the structure of RNA polymerase?
  16. E. Coli has how many copies of this RNA polymerase at any given time?
  17. How many different sigma factor have been found in E. Coli?
  18. What is the structure in the sigma factor that binds tightly to the DNA?
    Helix-turn-helix motif
  19. The sigma factor only binds to the DNA in what area of the DNA?
    Major Groove
  20. The Sigma factor recognizes the promotor by what?
    Hydrogen bonding between Pribnow boxes and the Amino Acid side chains in the Helix-turn-helix structure.
  21. As RNA polymerase moves along the DNA it causes an open complex of how many base pairs?
  22. What is the average pace of nucleotides per seconds of RAN polymerase?
  23. Behind the open complex of RNA polymerase what happens to the DNA?
    If rewinds back into a double helix.
  24. Describe the basic process of Transcription termination.
    Occurs when short RNA-DNA hybrid region is forced to seperate.
  25. Describe Rho- dependent termination.
    • Sequence near 3' end of newly made mRNA called the rut (Rho utilization) site is recognized and bound by rho protein (helicase).
    • GC rich region causes a loop to form.
  26. Describe the Rho independent termination.
    This loop causes RNA polymerase to pause at a U-rich sequence region, which is thought to be unstable causeing RNA polymerase to spontaneously dissociate from DNA.
  27. What is Intrinsic termination?
    No protein required for physical removal of RNA.