Genetics problem please help the whole homework assignment is due tomorrow at 4:10 pm
The L gene in guinea pigs controls hair length. The dominant allele L governs short hair, while the recessive allele l governs long hair. Hair color is specified by a second gene C that has codominant alleles, such that CYCY=yellow, CYCW=cream, and CWCW=white. Two short/ cream-haired pigs (LlCYCW) are crossed. Assuming independent assortment, predict the phenotypic ratio in the progeny of this cross for:
a. long yellow animals.
b. short cream animals.
c. long cream animals.
To solve this genetics problem, we first need to understand the alleles and how they are inherited.
The L gene controls hair length, with the dominant allele L representing short hair and the recessive allele l representing long hair. The C gene controls hair color, with the alleles CY and CW representing yellow and white respectively.
In the parents' cross (LlCYCW x LlCYCW), we can break down the genotype of each parent:
Parent 1:
Genotype: LlCYCW
Hair length allele: Ll (short hair)
Hair color allele: CYCW (cream color)
Parent 2:
Genotype: LlCYCW
Hair length allele: Ll (short hair)
Hair color allele: CYCW (cream color)
Now, let's determine the possible gametes from each parent:
Parent 1:
Gametes: L, l, CY, CW
Parent 2:
Gametes: L, l, CY, CW
To predict the phenotypic ratio in the progeny, we need to combine the possible gametes from each parent. We will use a Punnett square to do this.
________L______l____
CYCW| LYCYCW |LlCYCW|
CYCW| LYCYCW |LlCYCW|
In the Punnett square, we combine each possible hair length allele (L/l) from the top row with each possible hair color allele (CYCW) from the side column.
a. To predict the phenotypic ratio for long yellow animals, we look at the square labeled LYCYCW. This corresponds to the genotype LL (long hair) and CYCY (yellow color). The ratio in the progeny for this phenotype is 1:1.
b. To predict the phenotypic ratio for short cream animals, we look at the squares labeled LlCYCW. These correspond to the genotype Ll (short hair) and CYCW (cream color). The ratio in the progeny for this phenotype is 2:4, which can reduce to 1:2.
c. To predict the phenotypic ratio for long cream animals, we look at the squares labeled LYCYCW and LlCYCW. These correspond to the genotype LL (long hair) and CYCW (cream color) as well as Ll (short hair) and CYCW (cream color). The combined ratio for these phenotypes is 1:2.
Therefore, the predicted phenotypic ratios in the progeny of this cross are:
a. Long yellow animals: 1:1
b. Short cream animals: 1:2
c. Long cream animals: 1:2