- #1
cmantzioros
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The question:
In dogs, dark coat colour is dominant over albino, and short hair is dominant over long hair. If these effects are caused by two independently segregating gene pairs, write the most probable genotypes for the parents of each of the following crosses: (Use the symbols D and d for dark and albino coat colour alleles, and S and s for the short- and long-hair alleles, respectively.)
Parental Phenotypes Phenotypes of the Offspring
Dark, Short Dark, Long Albino, Short Albino, Long
a) dark short x dark short 89 31 29 11
b) dark short x dark long 18 19 0 0
c) albino short x albino short 0 0 28 9
d) dark long x dark long 0 32 0 10
e) dark short x dark short 46 16 0 0
f) dark short x dark long 29 31 9 11Attempt at solution:
I'm trying to write out the genotypes but there are so many possibilities. I know I can narrow it down using the data provided but I don't know what to look for. For example for letters (a) and (e):
dark short: DDSS DDSs DdSS DdSs
dark short x dark short (crossing possibilities):
DDSS x DDSS DDSs x DDSs DdSS x DdSS DdSs x DdSs
DDSS x DDSs DDSs x DdSS DdSS x DdSs
DDSS x DdSS DDSs x DdSs
DDSS x DdSs
Is this correct? If so, how would I go about deciding which ones would best fit the outcomes given?
I know how to find the genotypes given the crossing but I don't think I need to find the genotypes of all possible crosses to find the answer. Any suggestions?
*Sorry about the table... it looks fine when I write it here but in the post it's all scrunched up together. Don't know what to do about it.
In dogs, dark coat colour is dominant over albino, and short hair is dominant over long hair. If these effects are caused by two independently segregating gene pairs, write the most probable genotypes for the parents of each of the following crosses: (Use the symbols D and d for dark and albino coat colour alleles, and S and s for the short- and long-hair alleles, respectively.)
Parental Phenotypes Phenotypes of the Offspring
Dark, Short Dark, Long Albino, Short Albino, Long
a) dark short x dark short 89 31 29 11
b) dark short x dark long 18 19 0 0
c) albino short x albino short 0 0 28 9
d) dark long x dark long 0 32 0 10
e) dark short x dark short 46 16 0 0
f) dark short x dark long 29 31 9 11Attempt at solution:
I'm trying to write out the genotypes but there are so many possibilities. I know I can narrow it down using the data provided but I don't know what to look for. For example for letters (a) and (e):
dark short: DDSS DDSs DdSS DdSs
dark short x dark short (crossing possibilities):
DDSS x DDSS DDSs x DDSs DdSS x DdSS DdSs x DdSs
DDSS x DDSs DDSs x DdSS DdSS x DdSs
DDSS x DdSS DDSs x DdSs
DDSS x DdSs
Is this correct? If so, how would I go about deciding which ones would best fit the outcomes given?
I know how to find the genotypes given the crossing but I don't think I need to find the genotypes of all possible crosses to find the answer. Any suggestions?
*Sorry about the table... it looks fine when I write it here but in the post it's all scrunched up together. Don't know what to do about it.