- Scientists Are Investigating The Genetic Determinants Of Over Eating Using A Rat Model In A Randomly Breeding Laborator 1 (42.37 KiB) Viewed 304 times
- Scientists Are Investigating The Genetic Determinants Of Over Eating Using A Rat Model In A Randomly Breeding Laborator 2 (36.76 KiB) Viewed 304 times
- Scientists Are Investigating The Genetic Determinants Of Over Eating Using A Rat Model In A Randomly Breeding Laborator 3 (9.56 KiB) Viewed 304 times
A. How many genes are responsible for the observed phenotypic
variance at this trait?
AND
B. If, hypothetically, additive alleles on these two chromosomes
combinedly contribute 17.7 g/day to the phenotype; how many
polygenes were detected by this QTL mapping experiment?
(round to the nearest whole number)
Scientists are investigating the genetic determinants of over-eating using a rat model. In a randomly breeding laboratory colony, each rat will on average consume 60 g of feed per day with a variance of 20 g/day². Two inbred lines were created from this original population (after five generations of selection and inbreeding), one with a high food intake (mean consumption: 95 g/day) and one with low food intake (mean consumption: 36 g/day). The variance in both inbred lines is approximately the same (3 g/day2). During the first phase of selection for the high intake line, the researchers chose a group with mean intake of 103 g/day, and the resulting generation had a mean intake of 87 g/day. An F2 generation was also created by cross breeding the two inbred lines and allowing the resulting F1 to interbreed. Amongst the F2 only 0.10% showed a feed intake similar to the low line. In a QTL mapping experiment the F1 is backcrossed to the low intake parental line. In the offspring there is a bimodal phenotypic distribution with low (L) and intermediate (1) feed intake amongst individual rats. Markers A, B and C are on Chromosome 2, and markers D, E and F are on Chromosome 6 (assume that the P1 generation was true breeding for all marker loci: ABCDEF and abcdef, respectively).
Chromosome 6 Chromosome 2 Chromosoom 6 Chromosoom 2 Marker Genotype Phenotype Count Marker GenotypePhenotype Count Merker Genotipe Fenotipe Telling Merker Genotipe Fenotipe Telling DEF L 264 ABC L 423 DEF L 269 ABC L 436 deF 257 abC 442 def 234 abc 439 DeF L 232 AbC L 98 Def L 254 Abc L 95 dEF I 244 aBC I 96 dEf I 244 aBc I 95 DeF I 103 AbC I 89 Def 112 Abc 89 dEF L 64 aBC L dEf L 68 aBc L DEF 65 ABC I DEF 62 ABC deF L 63 abc L def L 62 abc L 85 84 33 32 32 29
Map the location of these gene(s) onto the appropriate chromosome(s), by giving the genetic distance between marker loci and potential QTL(s). Where there is independent assortment between marker and QTL, give the genetic distance as 50 CM. (round to the nearest whole number)