Bio 130 Ch 13

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Bio 130 Ch 13
2015-10-29 15:54:37
bio 130

ch 13
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    Gene Regulation
  2. Why are genes regulated?
    To produce the correct time and amount, and saves energy
  3. These are genes that are unregulated and have essentially constant levels of expression.
    Constitutive genes
  4. One typle of gene regulation is changes in the?
  5. In E. Coli when lactose is available two proteins are made. What are they?
    Lactose permease and B-Galactose
  6. What does lactose permease do?
    Trnasports lactose into the cell
  7. What does B-glactosidase do?
    Breaks down lactose
  8. THis is necessary to prodice different cell types in an organism.
    Cell Differentiation
  9. All of the organism's cell contain the same genome but express .....
    different proteomes
  10. What are some differences in bacterial gene regulation.
    Most commonly occurs at the level of transcription. Also, can control rate of translation. Can be regulated at protein or post-r\translation level.
  11. What are some differences in Eukaryotic gene regualtion?
    Transcriptional regulaion common. RNA processing. translation. Post-translation. and involves regulatory transcription factors
  12. These inhibit transcription and is a negative control.
  13. These increase the rate of transcription. Positive control.
  14. Transcriptional regulation also involves another molecule. These bind to regulatory transcription factor and cause conformational change. They determine whether or not regulatory transcription factor can bind to DNA.
    Small effector molecules
  15. What are the two domains in regulatory transcription factor thatt respond to small effector molecules.
    Site where proteins binds to DNA. Site specifically for small effector molecule.
  16. What is an Operon?
    A cluster of genes under transcriptional control of one promoter.
  17. Transcribed into mRNA, encodes more than one protein, and allows coordinated regulation of a group of genes with a common function.
    Polycistronic mRNA
  18. In E. Coli there is gene that codes for lactose metabolism. What does it look like?
    LacP containing LAcZ, LacY, LacA and regulatory sites LacO and CAP site.
  19. THis is part of the gene for lactose metabolism. what is lacP?
    lac promoter
  20. THis is part of the gene for lactose metabolism. what is lacZ?
  21. THis is part of the gene for lactose metabolism. what is lacY?
    lactose permease
  22. THis is part of the gene for lactose metabolism. what is lacA?
    galactosidase transacetylase
  23. Near the lac promoter are two regulatory sites:?
    lacO and CAP site
  24. Regulatory site: operator - provides binding site for repressor protein.
  25. Regulatory site:
    activator protein binding site
  26. THis gene codes for lac repressor. its considered a regulatoiry gene and has its own promotor.
  27. What is going on when Lac repressor protein binds to nucleotides of the. lac operator site preventing RNA polymerase from transcribing lacZ, lacY and lacA. RNA polymerase can bind but not move forward
    Lactose is absent
  28. What is going on when Allolactose is a small effector molecule – 4 molecules bind to lac repressor to prevent it from binding DNA. Process is induction – the lac operon is “inducible”
    Lactose is present
  29. CAP (ctabolite activator protein) is an...
  30. This is a glucose and represses lac operon
    Catabolite repression
  31. binds to activator protein called catabolite activator protein (CAP) or cAMP receptor protein (CRP)
    Small effector molecule, cAMP
  32. Glucose inhibits production of cAMP and so prevents binding of
    CAP to DNA
  33. Gene regulation involving CAP and cAMP is an example of?
    Positive control
  34. When cAMP binds to CAP, complex binds to CAP site near....
    lac promoter
  35. When both lactose and glucose are high, the lac operon is shut off
    Glucose uptake causes cAMP levels to drop, CAP does not activate transcription, Bacterium uses one sugar at a time, glucose
  36. When lactose is high and glucose is low, the lac operon is turned on
    Allolactose levels rise and prevent, lac repressor from binding to operator, CAP is bound to the CAP site, Bacterium uses lactose
  37. When lactose is low and glucose is high or low, the lac operon is shut off
    Under low lactose conditions, lac repressor prevents transcription of lac operon
  38. In E. coli, encodes enzymes required to make amino acid tryptophan. Regulated by a repressor protein encoded by trpR gene
    trp operon
  39. What's going on with tryptophan when the trp repressor cannot bind to operator site and operon genes transcribed?
    Tryptophan levels are low
  40. What's going on with tryptophan when the trp operon is turned off?
    Tryptophan levels are high
  41. Tryptophan acts as :
    A small repressor molecule or corepressor
  42. binds to its operator in the absence of its small effector molecule
    lac repressor
  43. binds to its operator only in the presence of its small effector molecule
    trp repressor
  44. What is involved with eukarotic transcription
    Activators, repressors, modulation, chromatin, and DNA methylation
  45. stimulate RNA polymerase to initiate transcription
  46. inhibit RNA polymerase to initiate transcription
  47. this is when smaal effector molecules, protein-protein interactions, and covalent modifications can modulate activators and repressors
  48. These activator proteins promote loosening up of the region in the chromosome where a gene is located, making it easier for RNA polymerase to transcribe the gene
  49. This usually inhibits transcription, either by blocking an activator protein or by recruiting proteins that make DNA more compact
    DNA Methylation
  50. There are three features of promoters in Eukary.
    TATA box, Transcriptional start site, and regulatoryt or responce elements
  51. 5’ – TATAAAA – 3’, 25 base pairs upstream from transcriptional start site. Determines precise starting point for transcription
    TATA Box
  52. Where transcription begins. With TATA box forms core promoter. By itself results in low level basal transcription
    Transcription start site
  53. Recognized by regulatory proteins that control initiation of transcription . Enhancers and silencers
    regulatory or responce elements
  54. What are the three proteins mediate transcription
    An RNA polymerase II, 5 different general transcription factors (GTFs), and large protein complex called mediator
  55. must come together at core promoter before transcription can be initiated
    GTFs and RNA polymerase II
  56. assembled GTFs and RNA polymerase II at the TATA box. Form basal transcription apparatus
    Preinitiation complex
  57. composed of several proteins. Partially wraps around GTFs and RNA polymerase II. Mediates interactions with activators or repressor that bind to enhancers or silencers. Controls rate at which RNA polymerase can begin transcription
  58. bind to DNA regions called enhancers
  59. bind to DNA regions called silencers
  60. 3 ways to control RNA polymerase II
    Activators and repressors regulater by binding to GTFs, regulate using a mediator, and recuit proteins that influence DNA packing
  61. DNA is associated with proteins to form compact chromatin. Chromatin packing affects
    Gene expression
  62. What happens when chromatin is packed to closely?
    transciption is difficult or impossible
  63. What happens when chromatin is packed open.
    Access to the DNA is allowed
  64. Some activators diminish DNA compaction near a gene. Recruit proteins to loosen DNA compaction. name them
    Histone acetyltransferase and atp-dependent chromatin remodeling enzymes
  65. Methylation can inhibit transcription in two ways, what are they?
    Methylation of CpG islands prevent activator and converting chromatin from an open to closed conformation.
  66. In Eukayotes where is gene expression commonly regulated?
    Level of RNA processing and translation
  67. What are the benefits of transcription being done at the RNA processing and translation level?
    Produce more than one mRNA transcript from a single gene and faster regulation,
  68. What are the alternative splicing of pre-mRNAs?
    processed before it becomes mature, and when there are multiple introns and exons splicing occurs in more than one way
  69. These are small RNA molecules that silence the expression of pre-existinf mRNAs.
    MicroRNAs (miRNAs or siRNA)
  70. Cut by dicer to release miRNA. Associates with cellular proteins to become. RNA-induced silencing complex (RISC). Upon binding, either
    mRNA degraded or, RISC inhibts translation
  71. Another way to regulate translation involves RNA-binding proteins that directly affect translational initiation
    Iron toxicity
  72. To prevent iron toxicity in mammals cell suthesize