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Title: In rats, gene B produces black coat color if the genotype is B–, but black pigme Post by: sam01 on Feb 16, 2015 In rats, gene B produces black coat color if the genotype is B–, but black pigment is not produced if the genotype is bb. At an independent locus, gene D produces yellow pigment if the genotype is D–, but no pigment is produced when the genotype is dd. Production of both pigments results in brown coat color. If neither pigment is produced, coat color is cream. A third independently assorting gene involved in determination of coat color in rats is the C gene. At this locus, the genotype C–permits expression of pigment from genes B and D. The cc genotype, however, prevents expression of coat color and results in albino rats.
1. Determine the genotype and phenotype of parents that produce the following progeny: 9/16 brown; 3/16 black; 4/16 albino 2. Determine the genotype and phenotype of parents that produce the following progeny: 3/8 black; 3/8 cream; 2/8 albino 3. Determine the genotype and phenotype of parents that produce the following progeny: 27/64 brown; 16/64 albino; 9/64 yellow; 9/64 black; 3/64 cream. 4. Determine the genotype and phenotype of parents that produce the following progeny: 3/4 brown; 1/4 yellow. Thank you for any help. please help!! Title: Re: In rats, gene B produces black coat color if the genotype is B–, but black pigme Post by: wizarddim on Feb 16, 2015 Umm. These are all Mendels Ratio's Just gotta remember them
a) Regular Di-hybrid cross AaBb * AaBb b) AABbCc* AABbCc c) Tri-Hybrid Cross- AaBbCc * AaBbCc d) aaBbCc*aabbCc e) aaBbCc*aaBbcc Here is how i reasoned this ones out, But im not a 100% sure didn't really expand em out on paper. A. Normal Di Hybrid B. The difference from this one and A is that you want Albino gene instead of black and cream. So how do you get rid of Black and cream? Make sure you only get AA. But how do you ensure you get albino 25% of the time is a simple Heterozygous cross ( Cc* Cc) 25% of the time you get the recessive allele. Expand the same thought process to get yellow but use B's C.Regular Tri-Hybrid Cross- Google it D and E are Tricky but you have to use the thought process from B. This time you don't want any grey or yellow you always need aa. for d they want cream 50% and Black 50% so what Mendel ratio gives you 50-50% ( Bb * bb) as per albino they want it 25% of the time so its just ( Cc* Cc) E. Following the same logic aa this time they want 75% black and 25% cream ( Bb*Bb) and albino they want 50-50 so its Cc*cc. Hope this Helps Do Verify my logic. Good luck Sorry about the spelling errors i am in class. |