*The normal color of snapdragons is red. Some pure lines showing variation in fl
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Question
*The normal color of snapdragons is red. Some pure lines showing variation in flower color have been found. Analyze the following crosses and do the following:2
Explain the inheritance of these colors (include number of genes, alleles and dominance relationships).
Determine the genotypes of the parents and the F1 of each cross.
Propose a biochemical pathway for flower color production in snapdragons.
Parents F1 F2
1. orange x yellow orange 3 orange: 1 yellow
2. red x orange red 3 red: 1 orange
3. red x yellow red 3 red: 1 yellow
4. red x white red 3 red: 1 white
5. yellow x white red 9 red: 3 yellow: 4 white
6. orange x white red 9 red: 3 orange: 4 white
7. red x white red 9 red: 3 yellow: 4 white
Explanation / Answer
1. . orange x yellow
YY orange X yy yellow
F1 Yy orange
F2 Yy X Yy
YY Yy Yy Orange ; yy Yellow
Single gene needed
orange dominant
2 alleles
2. orange x Red
rr orange X RR red
F1 Rr Red
F2 Rr X Rr
RR Rr Rr Red ; rr Orange
Single gene needed
Red dominant
2 alleles
3. Red x yellow
RR Red X rr yellow
F1 Rr Red
F2 Rr X Rr
RR Rr Rr Red ; rr yellow
Single gene needed
red dominant
2 alleles
4. Red x white
RR Red X rr white
F1 Rr Red
F2 Rr X Rr
RR Rr Rr Red ; rr white
Single gene needed
red dominant
2 alleles
5. Yellow X white
YYww X yyWW
F1 YyWw Red
F2 YyWw X YyWw
9 red: 3 yellow: 4 white
2 genes required
4 alleles needed
This is complementation effect.
Both genes yellow and white are dominant if it separately
present means. If both combine means it will produce new genotye.
Y - codes for substrate and W codes or enzyme
YW joins means E + S ------- E + P product.
The product turns into new color.
6. 5. Orange X white
OOww X ooWW
F1 OoWw Red
F2 OoWw X OoWw
9 red: 3 orange : 4 white
2 genes required
4 alleles needed
This is complementation effect.
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