(1) List all the genotypes you expect for the offspring that would result from m
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(1) List all the genotypes you expect for the offspring that would result from matings of two rats, each of which is heterozygous for the two genes referenced above. In front of each of the genotypes you list, specify the fraction of the offspring you would expect to possess it. na cross s behueeSsBb XS.Bh enchpic Raho SSBb (2) Lis t all he phenotypes you expect for the offspring that would result from the cross described above. In front of each phenotype you list, specify the fraction of the offspring you would expect to possess it. o Shiny aur dull hair bock Pimene Using your data from the previous question, answer the following. dal (1) What fraction of the offspring from this cross would you epect to show at least one recessive What fraction of the offspring from this cross would you expect to showat least one recessive phenotype? (2) What fraction of the offspring from this cross would you expect to show only one dominant phenotype? (3) What fraction of the offspring from this cross would you expect to be heterozygous for the color genei (4) What fraction of the offspring from this cross would you expect to be homozygous for at least one gene? (5) What fraction of the offspring from this cross would you expect to be homozygous recessive for at least one gene?Explanation / Answer
Dominant phenotypes- shiny hair and Black pigment
Recessive phenotypes- dull hair and brown pigment
2.1 So fraction of the offspring that show at least one recessive phenotype i.e shiny hair and brown pigment (3/16) and dull hair and black pigment (3/16) and dull hair and brown pigment (1/16)= 3/16 + 3/16 + 1/16= 7/16
2.2 Fraction of the offspring that show only one dominant phenotype i.e shiny hair and brown pigment (3/16) and dull hair and black pigment (3/16)= 3/16 + 3/16= 6/16
2.3. Fraction of offspring that would be heterozygous for the colour gene, i.e SSBb (2/16), SsBb (4/16) and ssBb (2/16)= 2/16+ 4/16 +2/16= 8/16= 1/2.
2.4. Fraction of offspring that would be homozygous for atleast one gene,i.e SSBB (1/16 ), SS Bb (2/16 ), SSbb (1/16 ), ssBB (1/16 ), ssBb (2/16 ) ssbb (1/16), SsBB(2/16), Ssbb (2/16). Adding all these together we get 12/16 or 3/4.
2.5. Fraction of offspring that would be homozygous recessive for atleast one gene i.e ssBB (1/16) , ssBb (2/16), ssbb (1/16),SSbb (1/16), Ssbb (2/16). Adding all these together we get 7/16.
Questions 1 and 5 are basically the same question.
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