MolBioExam2

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  1. Right handed helix found under normal, physiological conditions.
    B-form
  2. Left handed helix
    Z-form
  3. DNA helix formed in solutions w/ low water content, and in RNA.
    A-form
  4. The adjacent phosphate groups in backbone are closer together making it a shorter, wider helix than the other 2.
    A-form
  5. This helix form has a wide major groove that accommodates binding of an alpha-helix.
    B-form
  6. This helix form of DNA is unusual, but may form in transcriptionally active genomic regions.
    Z-form
  7. Here is a strand of DNA:
    5'-GATAGUTGGCA-3'
    What happened to this DNA?
    cytosine was deaminated
  8. How are successive nucleotides of a DNA strand joined?
    by phosphodiester bonds btwn 3' carbon of 1 nucleotide and 5'carbon of the next.
  9. Hydrophobic stacking is an interaction that helps what in DNA?
    help stabilize the 3D structure of DNA
  10. Which of the following is NOT true of genomic and cDNA libraries?
    A. Genomic libraries contain fragments of genomic DNA that are generated by partial digests w/ restriction enzymes.
    B. cDNA libraries contain cDNAs made 4rm mRNA.
    C. cDNA libraries contain seq 4rm expressed genes only.
    D. cDNA libraries typicallys contain control seq that direct transcription.
    E. Genomic libraries usually contain large fragments and are likely to be constructed in yeast / bacterial artificial chromosome vectors (BAC/YAC).
    D. cDNA libraries typicallys contain control seq that direct transcription.
  11. What's Western Blotting used for?
    to visualize specific proteins that have been separated by gel electrophoresis
  12. Transcriptomics is concerned w/ what?
    expression of RNA molecules. 
  13. The genomes of many organisms have been sequenced. What are the benefits?
    • genome-based precision medicine
    • trace our evolutionary history 
    • elucidate genetic patterns of medical interest 
    • identify genes of agricultural import
  14. RNA-seq is important in.....
    tool in transcriptomics ! 
  15. Eukaryotic genes...
    • encode RNAs that can catalyze chemical rxns (functional)
    • have introns 
    • encode for multiple forms of msgr RNA created by alternative splicing
  16. TRUE/FALSE. Action of euk topoisomerases stabilizes the binding of chromosomal DNA to histones.
    TRUE
  17. TRUE/FALSE. RNA pol cause + coiling in DNA duplex downstream (in front of) replication fork.
    TRUE
  18. TRUE/FALSE. Topoisomerases undergo conformational changes during course of unlinking DNA.
    TRUE.
  19. TRUE/FALSE. Type II topoisomerases from prokarytoes introduce - supercoils in DNA.
    TRUE.
  20. TRUE/FALSE. DNA pol causes + coiling in DNA duplex upstream (behind) replication fork.
    FALSE.
  21. How can repositioning nucleosomes affect transcription?
    • could cover a promoter resulting in repression of transcription
    • could expose a promoter resulting in activation of transcription
  22. Reasons why bacteria do NOT have nucleosome-like structures...
    • need to respond quickly to env and need ready access to genome 
    • cell division occurs 15 min or less, euks takes hrs / months 
    • a larger proportion of bacterial chromosome codes for protein
    • higher rates of metabolism in bacteria mean that much larger proportion of DNA is being transcribed / replicated at a given time.
  23. If amt of H1 increases in a region of chromatin, what will be its affect on compaction of DNA and transcription in that region?
    Tx will decrease in that region
  24. TRUE/FALSE. Histones are the largest component that is associated in euk chromatin.
    TRUE
  25. Compaction of DNA
    • serves a protective function
    • are enzymes that introduce and maintain coiling of dsDNA molecules 
    • are DNA-binding proteins that maintain structural organization in euks and prokaryotes
  26. How are epigenetic marks of a particular chromatin state preserved during cell division?
    A. Parental, marked H2A-H2B dimers stay associated w/ DNA strands during replication and recruit new H3-H4 tetramers.
    B. H2A-H2B dimers and H3-H4 tetramers come off during replication and assemble w/ unmarked histones. These new octamers then rebind to the newly replicated DNA to form nucleosomes.
    C. Parental, marked H3-H4 tetramers stay associated w/ DNA strands during replication and then recruit new H2A-H2B dimers.
    D. Histone chaperones make sure that at least one component of each new nucleosome is marked.
    B. H2A-H2B dimers and H3-H4 tetramers come off during replication and assemble w/ unmarked histones. These new octamers then rebind to the newly replicated DNA to form nucleosomes.
Author:
mnvang321
ID:
313299
Card Set:
MolBioExam2
Updated:
2015-12-16 05:16:05
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MolBio
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MolBioExams
Description:
Exam 2
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