Bio 214 exam IV answers

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Bio 214 exam IV answers
2014-05-09 01:22:12
cell bio

answers from exam 4
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  1. The double helix model of DNA shows two strands of DNA bonded together by hydrogen bonds btwn
    opposite complementary nitrogenous bases
  2. A nucleotide is made of which of the following chemical components?
    nitrogenous base, a phosphate group, and a ribose sugar
  3. Which of the following statements describes the eukaryotic chromosome?
    it consists of a single linear molecule of double-stranded DNA plus protein
  4. What is meant by the description "antiparallel" regarding the strands that make up DNA?
    The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand
  5. Which base pairs are found in DNA?
    A-T and C-G
  6. The structures that cap the ends of eukaryotic chromosomes are called:
  7. The DNA in eukaryotic chromosomes is folded into a compact form by interactions with:
  8. Histone proteins pack DNA into a repeating array of DNA-protein particles called:
  9. Histone acetylation results in what?
    Loosening of chromatin packing
  10. In his work with pneumonia-causing bacteria and mice Griffith found that
    non-pathogenic cells could become pathogenic if mixed with the contents of pathogenic cells
  11. Which type of radioactive isotope would you use to preferentially label protein and not DNA?
  12. DNA synthesis is initiated at origins of replication characterized by sequence elements that are more
    rich in A-T pairs
  13. At a replication fork, the leading strand is synthesized:
  14. What is the function of single-strand binding proteins in DNA replication
    bind to single-stranded DNA and prevent the single-strands from re-forming base pairs
  15. Mutation to the genome that have harmful consequences to an organism
    are usually eliminated from the population by natural selection
  16. To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?
    endonuclease, DNA polymerase I, DNA ligase
  17. What is the function of DNA polymerase III?
    to add nucleotides to the 3' end of a growing DNA strand
  18. What is the function of helicase?
    unwinding of the double helix
  19. what is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?
    DNA polymerase can join new nucleotides only to the 3' end of a growing strand
  20. Which of the following best defines "Okazaki fragments"
    short fragments of nucleotides laid down discontinuously on the lagging strand during DNA replication
  21. During DNA replication, the enzyme Primase performs what role?
    adds short RNA segments tot he lagging strand
  22. Transcription is best described as
    the synthesis of RNA using DNA as a template
  23. RNA polymerases join nucleotides through what kind of bond?
  24. To begin transcription, RNA polymerase recognizes nucleotide sequences in what region of the DNA?
    Promoter region
  25. In eukaryotes, what must assemble at a promoter before RNA polymerase can transcribe a gene?
    General transcription factors
  26. What structure is responsible for selecting and transporting only properly processed eukaryotic mRNAs into the cytoplasm?
    The nuclear pore complex
  27. In principle, how many reading frames in RNA can potentially be translated into proteins?
  28. WHat is NOT true about codons in mRNA molecules?
    some codons code for more than one amino acid?
  29. At what site do all charged tRNAs (except tRNA) first bind on the ribosome
    A site
  30. Which of the following statements regarding ribosomes is FALSE?
    Ribosomes are responsible for pre-mRNA splicing
  31. Which list of molecules is most directly involved in translation
    mRNA, tRNA, rRNA
  32. Alternative RNA splicing
    allows proteins of different sizes from a single mRNA
  33. Which of the following is the first event to take place in translation in eukaryotes?
    the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
  34. When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation were able to be stopped at this point, which of the following would you be able to isolate?
    an assembled ribosome with a polypeptide attached to the tRNA in the P site
  35. Of the following, which is the most current description of a gene?
    DNA sequence that is expressed to form a functional product: either RNA or polypeptide
  36. Bacteria can regulate the expression of multiple, related genes by
    organizing the genes into an operon and transcribing them as a single unit
  37. An inducible operon is usually associated with genes that code for enzymes in what type of pathway?
  38. The tryptophan operon is a repressible operon that is
    turned off whenever tryptophan is added to the growth medium
  39. Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?
  40. Two potential devices that eukaryotic cells use to regulate transcription are
    DNA methylation and histone modificaiton
  41. transcription factors in eukaryotes usually have DNA binding domains as well as other domains that can bind to other things. Other than DNA, what else would transcription factors be expected to bind?
    other transcription factors
  42. Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell?
    removal of the 5' cap
  43. The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called
    RNA interference
  44. Muscle cells differ from nerve cells mainly because they
    express different genes
  45. The structure of eukaryotic genes include control elements that are close to the promoter and others that are far away from the promoter. The distant control elements are grouped into a region of DNA called what?
  46. Which of the following is an example of post-transcriptional control of gene expression?
    the removal of introns and alternative splicing of exons
  47. Post-translational regulation of gene expression includes the targeted degradation of specific proteins using what?
  48. Although all of the steps involved in expressing a gene can in principle be regulated, for most genes the most important point of control is
    transcription initiation