Chapter 8

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mandy
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Chapter 8
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2010-06-29 16:07:29
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  1. Where is E. coli found?
    Large human intestine
  2. Is E. coli beneficial or harmful to the human intestines?
    beneficial
  3. What toxin does E. coli 0157 H7 have?
    Shiga
  4. How did E. coli 0157 H7 acquire the toxin from Shigella?
    When E. coli and Shigella came in contact with one another, E. coli picked up a Shigella plasmid and it made the E. coli harmful. It is now called E. coli 0157 because it acts like Shigella.
  5. What is genetics?
    The study of what genes are, how they carry info, how info is expressed, and how genes are replicated.
  6. What is a gene?
    A segment of DNA that encodes a functional product, usually is a protein.
  7. What is a chromosome?
    Structure containing DNA that physically carries hereditary information; the chromosomes contain the genes.
  8. What is a genome?
    It contains ALL the genetic information in a cell, not just the chromosomes.
  9. What is genomics?
    The molecular study of genomes.
  10. What is a genotype?
    The genes of an organism.
  11. What is phenotype?
    Expression of the genes.
  12. How many chromosomes does a human have?
    46
  13. How many chromosomes does a bacteria have?
    1
  14. Parent cells have how many strands of DNA in the cell?
    1
  15. E. coli can take 1 cell and turn it into 2 new cells in how long?
    20 minutes.
  16. What is transcription?
    Transcribing from DNA to RNA.
  17. What is a polymer of nucleotides composed of?
    Adenine, Thymine, Cytosine, and Guanine.
  18. What is the double helix associated with?
    Proteins.
  19. What is the "backbone" called?
    Deoxyribose-phosphate
  20. What kind of bonds hold the strands together?
    Hydrogen bonds.
  21. Where are the hydrogen held at?
    They are held at AT(Adenine, Thymine) and CG(Cytosine, Guanine).
  22. Strands are...
    antiparallel
  23. What is semi-conservative replication?
    The old strand of replication never leaves; it will always be there.
  24. How is DNA copied?
    • by DNA polymerase.
    • -in the 5' --> 3' direction
    • -initiated by an RNA primer
    • -DNA polymerases can only add nucleotides to the 3' end
    • -Leading strand is synthesized continuously
  25. What is the 5' --> 3' direction?
    the way that the molecules are aligned (they are antiparallel).
  26. What is the DNA synthesis process?
    One strand is continuous with no unattachments and the other will be discontinuous with Okazaski fragments.
  27. How often is the leading strand synthesized?
    Continuously
  28. How often is the lagging strand synthesized?
    Discontinuously
  29. How do bacteria replicate?
    Binary Fission.
  30. What is transcription?
    The process of creating an equivalent RNA copy of a sequence of DNA.
  31. DNA is transcribed to make...
    • RNA
    • -mRNA
    • -tRNA
    • -rRNA
  32. When does transcription begin?
    Transcription begins when RNA polymerase binds to the promoter sequence on the DNA.
  33. What direction does transcription take?
    5' --> 3' direction.
  34. When does transcription end?
    • The termination sequence.
    • -mRNA stops being made then is ready for translation.
  35. What makes RNA?
    DNA makes RNA.
  36. In Eukaryote cells, where is DNA found?
    In the nucleus.
  37. In a Prokaryotes, where is DNA found?
    There is no nucleus in Prokaryotes, so the DNA is found throughout the cell.
  38. mRNA makes?
    Protein.
  39. How is mRNA translated?
    In codons (three nucleotides)
  40. What is the start codon for mRNA translation?
    AUG
  41. Where does translation end?
    • Nonsense codons
    • - UAA, UAG, UGA
  42. What is protein made up of?
    Amino acids.
  43. What is sickle cell anemia?
    A result of one single amino acid that is missing.
  44. How many sense codons are there?
    64
  45. 64 sense codons on mRNA encode how many amino acids?
    20
  46. The genetic code is...
    degenerate or redundant
  47. What does tRNA carry?
    The complementary anticodon
  48. Why is there redundency in the genetic code?
    Because they are repeated sometimes.
  49. In eurkaryotes, mRNA has to leave what?
    The nucleus.
  50. In prokaryotes, there is no nucleus so mRNA is...
    Always available.
  51. Where do ribosomes attach?
    mRNA
  52. What is the ribosome doing?
    Making a protein.
  53. What is translation?
    Taking nucleic acids and turning them into amino acids.
  54. What is an anticodon?
    The complementary to what is on mRNA.
  55. What does tRNA do?
    tRNA brings in the complementary (anticodon) that goes with the mRNA.
  56. The tRNA brings the matches to the mRNA to make?
    A polypeptide chain.
  57. How are constitutive genes expressed?
    • Fixed rate.
    • -produce proteins that are always needed by cells.
  58. What is an operon?
    Set of 3 genes that work together to start/stop.
  59. What are inducible genes?
    They are genes turned on when they are needed.
  60. What are repressive genes?
    They stop transcription.
  61. What does a catabolite repression do?
    The pressence turns it off.
  62. How many genes are involved in lactose uptake in E. coli?
    3
  63. What is a promoter?
    Where mRNA polymerase initiates transcription.
  64. What is an operator?
    Turns transcription on or off.
  65. What are structural genes?
    They determine the protein structure.
  66. What are the promoter, operator, and structural genes called collectively?
    The lac operator (for lactose).
  67. What is the process that turns on transcription in the presence of an inducer?
    Induction.
  68. What is a substance that induces transcription of a gene called?
    An inducer
  69. In E. coli, the presence of causes (indirectly) the rapid production of the enzyme B-galactosidase.
    Lactose
  70. Lactose is considered to be?
    An inducer
  71. What gene encodes a repressor protein that switches the inducible and repressible operons on and off?
    The I gene.
  72. What kind of operon is a lac operon?
    Inducible
  73. The lac operon is an inducible operon so when lactose is not present, what happens?
    The repressor protein from the I gene binds to the operator site and therefore prevents transcription.
  74. (Induction)
    If lactose isn't present in transcription, what won't happen?
    Transcription won't happen.
  75. (Induction)
    What does transcription need in order to happen?
    Lactose
  76. (Repressible Operons)
    Structural genes are transcribed until when?
    Until they are turned off or repressed.
  77. (Repressible Operons)
    When there are excess products present, the product will as a what?
    A corepressor
  78. (Repressible Operons)
    What does the corepressor bind to?
    The repressor protein.
  79. (Repressible Operons)
    What happens if there are lots of a substance present?
    It can cause it to stop or prevent transcription.
  80. (Catabolite Repression)
    Enzymes for metabolism are constitutive, this meaning what?
    They are always present.
  81. (Catabolite Repression)
    When lactose is no longer available, what happens?
    Organisms are able to grow off of other carbon sources.
  82. (Catabolite Repression)
    When glucose is no longer available, what will it go after?
    Lactose
  83. (Catabolite Repression)
    Glucose grows
    Faster
  84. (Catabolite Repression)
    Lactose grows
    Slower
  85. What is mutation?
    A change in the genetic material.
  86. What are the 3 different forms that mutation may be in?
    Neutral, Beneficial, or Harmful.
  87. What is a mutagen?
    An agent that causes mutations.
  88. What are 3 examples of mutagens?
    UV light, Xrays, and Gamma rays.
  89. When do spontaneous mutations occur?
    They occur in the presence of a mutagen.
  90. What could happen if DNA is exposed to Xrays?
    It could cause a mutation such as cancer.
  91. Mutations occur in DNA and the mutation carries through to what process?
    The translation process.
  92. What is a missense mutation?
    A point mutation in which a single nucleotide is changed, resulting in a codon that codes for a different amino acid, which can result in proteins being not functional.
  93. What is a nonsense mutation?
    A point mutation in a sequence of DNA that results in a STOP codon.
  94. Which mutation (missense, nonsense, or frameshift) is the most serious?
    Frameshift mutation.
  95. What is frameshift mutation?
    Insertion or deletion of one or more nucleotide pairs.
  96. What is the spontaneous mutation rate?
    1 in 10^9 replicated base pairs or 1 in 10^6 replicated genes.
  97. What is the mutagen rate?
    10^-5 or 10^-3 per replicated gene.
  98. How many types of mutagens are there?
    • 4
    • -chemicals-organic
    • -UV light
    • -xrays
    • -gamma rays- nuclear
  99. Which happens more frequently, mutagens or spontaneous mutation?
    Mutagens.
  100. What may be structurally similar to nucleotides and will cause base pair mutations in the DNA?
    Chemical Mutagens.
  101. What may cause small deletions or insertions in the DNA which can result in frameshift mutations?
    Chemical mutagens.
  102. What is Aflotoxin?
    • They are naturally occuring mycotoxins.
    • -Aspergillus flavus
  103. Where can Aspergillus flavus be found?
    In peanut butter. It is a mold.
  104. What is ionizing radiation?
    Xrays and Gamma rays
  105. What does ionizing radiation cause?
    It causes the formation of ions and free radicals that can react with nucleotides and the deoxyribose-phosphate backbone.
  106. What can fragment the DNA and cause breaks in the chromosomes?
    Ionizing radiation.
  107. What can radiation kill?
    It can kill organisms.
  108. What kind of radiation causes thymine dimers?
    • UV radiation.
    • -thymine dimers are 2 thymines together in DNA
  109. How can mutations or carcinogens be detected in a culture?
    • 1. Ames test
    • 2. Replica plating
  110. Which mutation detection procedure uses sterile velvet/felt as an inoculum?
    Replica plating.
  111. How do bacteria and humans transfer genes?
    Vertically
  112. When do vertical gene transfers occur?
    They occur during reproduction between generations of cells.
  113. What are horizontal gene transfers?
    The transfer of genes between cells of the same generation.
  114. What transfer is between 2 organisms?
    • Horizontal
    • -E. coli 0157
  115. What does a horizontal gene transfer need?
    A donor cell and a recipient cell.
  116. What does virulent mean?
    Harmful
  117. What does avirulent mean?
    Unharmful
  118. What is transformation?
    Genes are transferred from one bacterium to another as "naked" DNA.
  119. What is bacterial conjugation?
    The transfer of genetic material between bacterial cells by direct cell-to-cell contact between two cells.
  120. What is F+?
    F+ is the donor cell that carries a plasmid(DNA).
  121. What is F-?
    F- is the recipient cell that receives the plasmid(DNA).
  122. What happens to F- after it receives the plasmid?
    It becomes F+.
  123. What does "F" stand for?
    Fertility.
  124. What happens if "F factor" gets into DNA?
    It will continue to replicate itself.
  125. What is transduction?
    The process by which DNA is transferred from one bacterium to another by a virus.
  126. What is a bacteriophage?
    A virus that infects bacteria.
  127. What is a conjugative plasmid?
    Carries genes for sex pili and transfer of the plasmid.
  128. What are dissimilation plasmids?
    • They encode enzymes for catabolism of unusual compounds.
    • Example: Psuedomonas sp that can have plasmids able to produce enzymes to degrade toluene, camphor, and hydrocarbons. (used in bioremediation of oils)
  129. What are Psuedomonas good at resisting?
    Resisting antibiotics.
  130. Can code for proteins that enhance pathogenicity.
    Plasmids.
  131. What are R factors?
    They are resistance factors. They encode antibiotic resistance.
  132. What is toxic shock?
    Exfolliation of skin, causes circulatory problems.
  133. Exfoliative toxin of Staphylococcus aureus, neurotoxin of Clostridium tetani, are examples of?
    pathogenic plasmid.
  134. What are transposons?
    Segments of DNA that can move from one region of DNA to another.
  135. Transposons occur how often?
    Rarely
  136. Transposons contain insertion sequences for?
    Cutting and resealing DNA (transposase)

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