GENETICS - BIOL 7    Quiz 5        October 5, 2004        NAME:   solution

Solve the following mapping problems. Your final answers should include the genotypes and phenotypes of both parents with the genes arranged in the correct order and in the correct allelic configuration (i.e. dominant and recessive alleles arranged properly on each chromosome),  map distances, and interference.  Place the completed maps neatly and clearly in a box in the upper right of the answer blank!    it is difficult to put it there in this format, so I put it down below -- but you'll notice that it is still easy to see & read!
                                                                                                   
1.  Analyze the following three-point cross: GgHhRr X gghhrr: 
  offspring phenotypes                                                                           G --------------- r ------------- h 
  GHR    112     Ghr/gHR are the parental (NCO) offspring                    g --------------- R ------------H 
  GHr       66      GhR/gHr are the DCO offspring                                 229 + 11 = 240       129 + 11 = 140 / 2000
  GhR        4        so ... if    P       then     DCO                                              = 12 %                      =  7%
  Ghr      811                Ghr/gHR  ......  GHr/ghR
  gHR     820                Grh/gRH  ......  GRh/grH  = this one                    I = 1 - 11 / (.12)(.07)(2000)
  gHr          7                HgR/hGr  ......  HGR/hgr                                                = 1 - 11 / 16.8
  ghR        63                                                                                                     = 1 - .65        = 0.35  
  ghr       117              so R is in the middle                                              

G -- 12 -- r -- 7-- h        x         g -- 12-- r --7 -- h       g -------- R -------H                   g -------- r ------ h phenotypes:    GRH          x                 grh                                      I =  0.35

Are the number of double crossovers more, fewer, or the same as expected?        fewer

2.  Analyze the following three-point cross: GgHhRr X gghhrr: 
  offspring phenotypes                                                                           H --------------- g ------------- r
  GHR      10      GhR/gHr are the parental (NCO) offspring                   h --------------- G ------------ R 
  GHr         2      GHr/ghR are the DCO offspring                                 27 + 3 = 30       37 + 3 = 40 / 204
  GhR       68       so ... if    P       then     DCO                                         = 15 %                      =  20 %
  Ghr        13                GhR/gHr  ......  GHR/ghr
  gHR       24                GRh/grH  ......  Grh/gRH                                      I = 1 - 3 / (.147)(.196)(204)
  gHr        69                Hgr/hGR  ......  HGr/hgR  = this one                               = 1 - 3 / 5.88
  ghR          1                                                                                                     = 1 - .51        = 0.49
  ghr         17              so G is in the middle                                              

H -- 15 -- g -- 20 -- r        x        h -- 15 -- g -- 20 -- r       h --------- G ------- R                   h -------- g --------- r phenotypes:    HGR          x                 hgr                                      I =  0.49

Are the number of double crossovers more, fewer, or the same as expected?        fewer





Are the number of double crossovers more, less, or the same as expected?