Microbiology Chapter 7

Card Set Information

Microbiology Chapter 7
2014-03-04 15:43:53
Microbiology Chapter
Microbiology Chapter 7
Microbiology Chapter 7
Show Answers:

  1. What is a nucleotide?
    nucleobase, phosphate group, sugar
  2. What are the four nucleobases?
    • Adenine
    • Thmine
    • Cytosine
    • Guanine
  3. How many nucleobases code for an amino acid?
  4. Define DNA replication
    The DNA is duplicated before cell division so that its encoded information can be passed on to the next generation
  5. What is involved in gene expression
    Transcription and translation
  6. What is transcription?
    copying of the information encoded in DNA into RNA
  7. What is translation
    interpreting information carried by RNA to synthesize the encoded protein
  8. What is the central dogma of molecular biology?
    Dna > RNA > protein
  9. What are the three types of RNA?
    • mRNA
    • tRna
    • rRna
  10. Why is replication semiconservative?
    Each new strand also contains one of the original strands
  11. Where does initiation of DNA replication begin?
    Origin of Replication
  12. What is needed to begin DNA replication?
    Primase- synthesizes a short piece of RNA (primer) that are complementary to exposed DNA
  13. What does DNA polymerase do?
    works from 5` end and adds complementary nucleotide to template
  14. What does a helicase do?
    unzips DNA strands at replication forks in order to reveal more template
  15. Which end starts the leading strand?
    5` end
  16. Which end starts the lagging strand?
    3` end
  17. Which strand contains Okazaki Fragments?
    Laggin Strand
  18. What does DNA Ligase do?
    seals gaps between fragments by forming a covalent bond between the two
  19. What is transcription?
    the process of synthesizing RNA from a DNA template
  20. What is translation?
    encoded information by a mRNA transcript is used to synthesize proteins
  21. What is an RNA polymerase?
    sythesizes single stranded RNA from a DNA template
  22. What is a promoter?
    • used in transcription
    • DNA sequence where the RNA polymerase binds and initiates transcription
  23. What is a terminater?
    DNA  sequence that stops transcription
  24. Which strand is copied by RNA polymerase?
    the positive strand is mirrored while the minus strand serves as a template
  25. What is monocristronic?
    When a transcript carries 1 gene
  26. What is polycristronic?
    when a transcript carries more than >2 genes
  27. What is a Sigma factor?
    part of RNA polymerase that recognizes the promoter, each sigma factor recognizes a different promoter
  28. What is elongation of RNA Transcript?
    once the RNA polymerase has reached the 3` end of a nucleotide the prior can close while the next opens, allowing a new polymerase to attach
  29. What are the 3 major structures of translation?
    • mRNA
    • Ribosome
    • tRna
  30. What is a codon
    three nucleotides that encode an amino acid
  31. What is the reading frame?
    The grouping of nucleotides into groups of 3
  32. Why is the genetic code redundant?
    because more than one codon can code for one amino acid
  33. What do ribosomes do during translation?
    string together the amino acids via a peptide bond
  34. What does the tRNA do during translation?
    Each tRNA pairs with a codon to deliver the appropriate amino acid
  35. What is the start codon
  36. What are the three ribosome sites?
    A >P>E
  37. What is a stop codon
    a codon that tRNA doesn't recognize and therefore stops translation
  38. What is a chaperone?
    • used post-translation
    • helps fold polpeptide into a 3D structure
  39. What is a signal sequence?
    • used in post-translation
    • a specific series of hydrophobic amino acids that are removed and mark a polypeptide for transport
  40. What is signal transduction
    transmits information from outside the cell to inside
  41. What is Quorum Sensing?
    when an organism sense the density of its own population via extracellular signaling molecules
  42. What is a 2-component regulatory system?
    • An integral sensor protein that has a sensor and response regulator
    • senses changes in environment and phosphorylates the response regulator inside the cell to turn on/off certain genes
  43. What is phase variation?
    routine switching on/off of certain genes
  44. What is Antigenic Variation*
    • an alteration in the characteristics of certain surface proteins
    • ex. Pilin in N. gonorrhoeae
  45. What is an operon?
    a set of reulated genes transcribed as a single polycristronic message
  46. What is a regulon?
    Separate operons controlled by a single regulatory mechanism
  47. What is global control?
    simultaneous regulation of numerous genese
  48. What are the three regulatory processes that describe enzymes?
    • constitutive- always on
    • Inducible- not usually on, but can be turned on
    • Repressible- Usually on, but can be turned off
  49. What is constitutive enzyme?
    An enzyme that is always on
  50. What is an inducible enzyme?
    An enzyme that is usually off, but is turned on
  51. What is a repressible enzyme
    An enzyme that is usually on, but can be turned off
  52. What is an alternating sigma factor?
    • Recognizes promoters controlling genes needed in non-routine situations
    • ex. sporulation
  53. What is a DNA-binding protein?
    protein that can either block transcription or facilitate it
  54. What are the two types of repressors in transcription?
    • Induction
    • Repression
  55. What occurs during induction
    blocks RNA polymerase from binding to a promoter, effectively turning the gene off
  56. What occurs during repression?
    Cannot bind to DNA unless a corepressor is present in order to block transcription
  57. What occurs when an activator is present?
    • enhances the ability of RNA polymerase to transcript
    • binds to activator binding site preceeding the promoter
  58. What is the lac Operon model?
    encodes proteins that are involved in transport and degradation of lactose when glucose is not available in E. coli