Lambda -Genetics ex

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cooxcooxbananas
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Lambda -Genetics ex
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2012-11-12 17:53:37
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genetics ex
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Genetics Ex
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  1. A lambda is..
    A phage (virus) that infects E. Coli
  2. what is the structure of the lambda phage from top to bottom?
    • Head (Capsule) with DNA inside it
    • Tail
    • End Plate with connected
    • Tail fibers
  3. The genome of the phage DNA is a ________bp, ________-stranded, _______ DNA.
    • 50,000 bp
    • double-stranded
    • circular DNA
  4. What two life cycles can temperate phages follow?
    • lysogenic cycle
    • lytic cycle
  5. what is a prophage?
    phage DNA intergrated into the host genome
  6. What are the steps of the lytic cycle?
    • 1. Phage injects its DNA into cytoplasm
    • 2. Phage DNA directs the synthesis of many new phages
    • 3. Cell lyses and releases the new phages
    • 4. New Phages can bind to bacterial cells
  7. What are the steps of the lysogenic cycle?
    • 1. Phage injects its DNA into cytoplasm
    • 2. Phage DNA intergrates into host chromosome
    • 3. Prophage DNA is copied when cell divides
    • 4. On rare occasion, a prophage may be excised from host chromosome
  8. Bacterial diseases are actually the result of...
    lysogenic phage within the bacteria
  9. Corynebacterium diphtheriae produces the toxin of...
    diphtheria
  10. Corynebacterium diphtheriae produces the toxin of diphtheria only when it is....
    infected by the phage β.
  11. Vibrio cholerae produces ...
    cholera toxin
  12. Vibrio cholerae produces cholera toxin, when it is....
    infected with the phage CTXφ
  13. Clostridium botulinum causes
    botulism
  14. Clostridium botulinum causes botulism; some
    strains harbor the toxin genes on a.....
    lysogenic phage
  15. Streptococcus pyogenes causes...
    scarlet fever
  16. Streptococcus pyogenes causes scarlet fever toxin genes on...
    phage T12.
  17. Clostridium tetani causes....
    tetanus
  18. What are the four main section of the lambda genome arrangment?
    • Lysogeny (recombination)
    • Lysogeny
    • Lysis
    • Lytic (Coat protein)
  19. What kind of genes are the early promoters and operators of the lambda phage genome?
    lysogenic genes
  20. What kind of genes is the att protein of the lambda phage genome?
    lysogenic gene (recomb.)
  21. What kind of genes is the int protein of the lambda phage genome?
    lysogenic gene (recomb.)
  22. What kind of genes is the xis protein of the lambda phage genome?
    lysogenic gene (recomb.)
  23. What kind of genes is the alpha protein of the lambda phage genome?
    lysogenic gene (recomb.)
  24. What kind of genes is the beta protein of the lambda phage genome?
    lysogenic gene (recomb.)
  25. What kind of genes is the gamma protein of the lambda phage genome?
    lysogenic gene (recomb.)
  26. What kind of genes is the clll prottein of the lambda phage genome?
    lysogenic gene
  27. What kind of genes is the N protein of the lambda phage genome?
    lysogenic gene
  28. What kind of genes is the cro protein of the lambda phage genome?
    lysogenic gene
  29. What kind of genes is the cll protein of the lambda phage genome?
    lysogenic gene
  30. What kind of genes is the Q protein of the lambda phage genome?
    lytic gene (late regulator)
  31. What kind of genes is the S protein of the lambda phage genome?
    Lytic gene (lysis proteins)
  32. What kind of genes is the R protein of the lambda phage genome?
    lytic gene (lysis proteins)
  33. What kind of genes is the cos protein of the lambda phage genome?
    lytic gene (lysis protiens)
  34. What kind of genes is the head gene of the lambda phage genome?
    Lytic genes (coat proteins)
  35. What kind of genes is the Tail genes of the lambda phage genome?
    Lytic genes (Coat proteins)
  36. what do PR and PL promoters express?
    N and cro Genes only
  37. What is the "Early" immediate early gene expression in the lytci cycle?
    PR and PL promoters express N and cro genes.
  38. the N protein in the lambda genome is an....
    antiterminator protein
  39. The N protein allows...
    read through of early terminators to give delayed early gene expression
  40. the Q protein in the lambda genome is an...
    antiterminator protein
  41. The Q protein allows...
    PR' to read through to give late gene expression
  42. N-mediated Antitermination allows ....
    expression of Delayed Early Genes, including Q
  43. Q-mediated Antitermination allows...
    expression of Late Genes from PR’including phage proteins and lysis genes
  44. the main three factor in the gene expression of the lytic cycle is...
    • Immediate Early genes expressed from PR and PL yield Cro and N
    • N-mediated Antitermination allows expression of Delayed Early Genes, including Q
    • Q-mediated Antitermination allows expression of Late Genes from PR’ including phage proteins and lysis genes
  45. virulent phages only undergo what life cycle?
    lytic cycle
  46. What is the key of lysogenic gene expression?
    CI, the lambda repressor
  47. What is not expressed from any of the promoters in the lytic cycle?
    CI, the lambda repressor
  48. About how many bp are in the lysogenic lambda genome?
    48,000
  49. The lambda repressor (CI) shuts off....
    all other lambda genes except itself.
  50. the lysogenic cycle gene expression ______ the same as the lytic cyle.
    starts
  51. The two delayed early genes in the lysogenic cycle gene expression is...
    CII and CIII
  52. PRE is not active...
    on its own
  53. The PRE must be activated by.....
    CII
  54. in the lambda repressor structure, the regions that make contact with the DNA are the...
    alpha-helical regions
  55. What part of the lambda repressor is responsible for dimerization?
    The COOH-terminal domain
  56. What part of the lambda repressor is responsible for DNA binding?
    NH2 terminal domain
  57. what is the basic structure of the lambda repressor?
    helix-turn-helix
  58. What does the repressor (CI) do once its made to shut off all lambda gene but its own?
    It binds to operator sequences
  59. What does CI binding to OR do to PR?
    causes transcription towards cro and PRE towards CI.
  60. What does CI binding to OR do to PRM?
    • yields more repressor from PRM transcription
    • shuts off ALL lambda gene except CI
  61. When repressor is bound to OR1 and OR2 it shuts off...
    PR and PL
  62. Repressor bind to what to operaters almost equally?
    OR1 and OR2
  63. what operator does the repressor bind to the least?
    OR3
  64. When repressor is bound to OR1 and OR2 it shuts off PR and PL and activates...
    PRM
  65. What are the steps of gene expression in the lysodenic cycle?
    • 1) Immediate Early Genes expressed PR and PL
    • 2) N Mediated Antitermination of Delayed Early Genes Including CII (and CIII)
    • 3) CII Activates PRE which yields a small amount of Repressor
    • 4) CI binds to OR1 and OR2, which shuts off PR and PL and Activates PRM
    • 5) All Lambda Genes are shut off except CI
  66. CII Activates PRE which yields a small amount of...

    Repressor
  67. The one early gene that is key for lytic gene expression is...
    Cro
  68. The two delyaed early genes that are important for lysogeny is...
    CII and CIII
  69. Cro is a _________ protein
    DNA binding
  70. Cro is a DNA binding protein that binds to..
    OR and OL
  71. Cro will bind to _____ more than _____ and _____ more than _____.
    • OR3 more than OR2
    • OR2 more than OR1
  72. When Cro occupies OR3 it shuts off...
    PRM
  73. The "Genetic Switch" is a race between....
    CI (repressor) and cro
  74. in the genetic switch, CI leads to .....
    lysogeny
  75. in the genetic switch, CI leads to lysogeny by binding to...
    OR1=OR2>OR3
  76. in the genetic switch Cro leads to ...
    lytic
  77. in the genetic switch, Cro leads to lytic by binding to...
    OR3>OR1=OR2
  78. What control whether CI or Cro wins in the genetic switch race?
    An E.coli protein called HflA
  79. what is HflA?
    An e coli protein thats an ATP dependent protease cleaves CII
  80. The Induction of lysogens, occurs in response to...
    DNA damage
  81. What occurs in response to DNA damage?
    Induction of lysogens
  82. The RecA protein is part of a ....
    DNA damage repair system
  83. What induces cleavage of Repressor (CI)?
    RecA
  84. RecA induces cleavage of....
    Repressor (CI)
  85. In RecA mediated cleavage, CI binds to OR1 and OR2 to activate ______ and repress _____.
    • PRM
    • PR
  86. E.coli O157:H7 contains a lysogen of a lambda like....
    phage 933W
  87. E.coli O157:H7 contains a _______ of a lambda like phage 933W
    lysogen
  88. With regard to promoting the lytic or lysogenic cycle, what would happen if the cro gene were missing from the λ genome?
    The lysogenic cycle would occur because cro protein is necessary to initiate the lytic cycle.
  89. With regard to promoting the lytic or lysogenic cycle, what would happen if the CI gene were missing from the λ genome?
    The lytic cycle would occur because cI encodes the λ repressor, which prevents thelytic cycle.
  90. With regard to promoting the lytic or lysogenic cycle, what would happen if the CII gene were missing from the λ genome?
    The lytic cycle would occur because cII protein is necessary to initiate the lysogenic cycle.
  91. With regard to promoting the lytic or lysogenic cycle, what would happen if the int gene were missing from the λ genome?
    Both cycles could try to initiate, but the lysogenic cycle would fail because it would be unable to integrate into the host chromosome.
  92. With regard to promoting the lytic or lysogenic cycle, what would happen if the CII and cro genes were missing from the λ genome?
    Neither cycles could occur.
  93. PRM and PR transcribe in ________ directions
    opposite
  94. The λ repressor will first bind to...
    OR1 and then OR2.
  95. The binding of the λ repressor to OR1 and OR2 inhibits transcription from...
    PR
  96. The binding of the λ repressor to OR1 and OR2 inhibits transcription from PR and thereby switches off...
    the lytic cycle
  97. Early in the lysogenic cycle, the λ repressor protein concentration may become so high that it will occupy.....
    OR3.
  98. When the λ repressorconcentration begins to drop, it will first be removed from...
    OR3
  99. The removal of the λ repressor from OR3 allows...
    allows transcription from PRM and maintains the lysogenic cycle.
  100. the cro protein has its highest affinity for OR3 so it ...
    binds there first
  101. The cro protine binding to the OR3 blocks...
    transcription from PRM
  102. The cro protine binding to the OR3 blocks transcription from PRM and thereby switches off...
    lysogenic cycle
  103. cro binding to OR1 or OR2 turns down...
    the expression from PR
  104. A mutation in PR causes its transcription rate to be increased 10-fold. Do you think this mutation would favor the lytic or lysogenic cycle?
    It would first increase the amount of cro protein so that the lytic cycle would be favored.
  105. When an E. coli bacterium already has a λ prophage integrated into its chromosome, another λ phage cannot usually infect the cell and establish the lysogenic or lytic cycle. Based on your understanding of the genetic regulation of the λ life cycles, why do you think the other phage would be unsuccessful?
    A cell that has a λ prophage is making a significant amount of the λ repressor. If another phage infects the cell, the λ repressor inhibits transcription from PR and PL and thereby inhibits the early steps that are required for either the lytic or lysogenic cycles.

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