Genetics Final EXAM

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Genetics Final EXAM
2011-12-06 02:58:00
Genetics Mutations dna genes

dr. dodd genetics on mutations
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  1. in normal body tissue- alters cellular function or tumors
    may have vast effects on individual
    not passed on to offspring
    somatic mutations
  2. mutation in gametes or cells producing gametes
    little or no effect on individual
    passed down to all cells of zygote
    -passed to subsequent generations
    -source of new alleles
    -phenotypic variability
    germinal/germ line mutation
  3. name the types of point mutations
    nonsense, missense, silence, neutral
  4. nonsense
    a stop codon substitution
  5. an amino acid substitution(Codon for different a.a.)
  6. synonymous codon, no change in a.a. (ACA to ACU)
  7. no change in final protein/ no change in functional protein
  8. induced
    • influenced by extraneous factors, result of agents
    • -radiation
  9. mutations that just happen- conditions dont induce
    -bacteria and antibiotics
  10. whether a mutation is harmful depends on
    • 1. environment
    • 2. nature of the mutation
  11. Change in reading frame caused by deletion or addition of base/s
    Changes every codon downstream
    generally causes loss of function
    usually a massive missense or nonsense
    Frameshift mutation
    ex of?
    silent/neutral mutation
    Missense mutation
    ex of?
    nonsense mutation- doesnt make sense!
  15. Common causes of Spontaneous mutations(lead to errors in DNA replication/repair?
    • Tautomeric shifts
    • deamination
    • depurination
    • ultraviolet radiation
  16. # cause of point mutations
    Tautomeric shifts
  17. all 4 bases may exist in one of two alternate forms
    -normal form more stable
    -occasionally spontaneously switch
    --H shifts place
    Tautomeric shifts
  18. In a tautomeric shift
    Ct binds to
    Gt binds to
    At binds to
    Tt binds to
    • A
    • T
    • C
    • G
  19. A C C G T A C G
    T G G T A T G C
    G doesnt bind to T- probably a Tautomeric shift!
  20. Bases spontaneously lose an amino group
    -changes structure/base pairing affinities leads to pointmutations
    -happens during replication
    deamination of bases
  21. Depurination of Bases
    • Purine bases spontaneously released from sugar-phosphate backbone of dna.
    • -replaced with -OH
    • -may be corrected
    • -nucleotide may be deleted
    • -leading to frameshifts
  22. UV radiation produces ____ problems
  23. bonds form between two adjacent thymines on one strand
    -leads to deletion of two bases
    -Cytosine converted to cytosine hydrate
    leading to mispairing bases= Frameshifts
    Ultra-violet radiation light damage
  24. what are two kinds of adaptive enzymes?
    Inducible/ repressible
  25. Constitutive enzymes
    always on/ enzyme always produced
  26. 2 different enzymes for gene regulation in prokaryotes
    constitutive and adaptive enzymes
  27. inducible enzymes(LAC operon)
    • needed for catabolism
    • only on if substrate is present
    • substrate is inducer
  28. TRP operon
    • Repressible system
    • -always on
    • -involved in anabolism
    • -feedback inhibition(the end product will turn off the system)
    • -end product is repressor
  29. Jacob and monad
    -system of 3 structural genes plus regulatory genes
    -gene products digest lactose
    -ONLY needed if lactose is PRESENT
    Lac operon
  30. polycistronic genes
    going to be transcribed onto 1 mRNA
  31. "i" gene of lac operon
    inhibitor gene- produces inhibitor protein that inhibits transcription
  32. "p" gene of lac operon
    promoter attracts polymerase
  33. "o" gene of lac operon
    operator- allows binding of inhibitor protein under the right circumstance(presnce of lactose binding to inhibitor) causing transcription
  34. as enzymes digest lactose, inhibitor protein is released. Inihibitor binds again to operator
    Transcription stops
  35. second level of control of lac operon
    -prevents full transcription of lac genes unless neccessary
    catabolite repression of lac operon
  36. in the presence of both glucose and lactose lac operon is on
    at very LOW levels
  37. ____ is a better energy source than lactose
  38. in absence of glucose the lac operon
    is fully turned on (full force)
  39. ______ levels regulate the efficiency of LAC promoter
    glucose/cyclicAMP(catabolite of glucose)
  40. In catabolite repression of lac operon, digestion of glucose
    converts cAMP to ATP
  41. High Glucose=___cAMP
    Low Glucose=___cAMP
    • low
    • high
  42. the lac promoter is a sucky promoter so we use
    cAMP/CAP(catabolite activator cap) to bind to the promoter and increase efficiency and therefore increa transcription.
  43. in the presence of both lactose and glucose, the lac operon is on but
    not working good or just a little bit
  44. No cAMP, the promotor remains weak=low transcription if ___ is present
  45. the repressible system
    TRP operon- on until something turns it off
  46. 5 polycistronic structural genes plus regulatory genes
    -gene products synthesize tryptophan
    trp operon
  47. "r" of TRP operon
    • repressor gene produces aporepressor protein
  48. "p" of trp operon
    promoter- really good
  49. t1-t5
    five "tryptophan synthetase" genes of TRP operon
  50. Aporepressor cannot bind to ___ by itself. its nonfucntional
  51. Major difference b/w Lac and Trp operon?
    repressor cannot repress operator by itself
  52. aporepressor must bind to ____, then the complex binds to the ____ to stop transcription.
    produced tryptophan, operator
  53. Attenuation of trp operson
    • Stopping/turning down
    • 2nd level of trp regulation to ensure genes NOT transcribed if tryptophan is present
  54. why is TRP operon expensive?
    • the 5 trp structural genes are expensive to transcrible/translate
    • tryptophan synthesis is expensive
  55. Leader/ attenuator in TRP?
    • pair of inverted repeats that alternate binding possibilities
    • -2 ways the Rna can fold up. will do one or the other. (forming stem loop)
  56. in trp attenuation Rna transcribed from 1 + 2 may form stem loop in which 3 + 4 also will or
    only 2 +3 will form stem loop
  57. What controls formation of stem loops?
    tryptophan levels!
  58. series of UUUUUU uracils close to 3-4 stem loop
    attuenation stopper/ transcription terminator
  59. when there is no typtophan lac operon continues to transcribe due to
    the series of UUU far down after the 2-3 stem loop. the UUs have to come after the 4th segment