in guinea pigs, the allele for a rough coat (R) is dominant over the allele for smooth coat (r). Two guina pigs that are heterozygous for a rough coat, mate and produce offspring. What is the probability that the offspring will have a smooth coat?
Rr x Rr
offsprin: RR, Rr, rR, rr
smooth coat rr,1 in 4
To determine the probability of the offspring having a smooth coat, we need to use Punnett squares to cross the parents' genotypes. Let's represent the dominant rough coat allele (R) and the recessive smooth coat allele (r) for the parents as follows:
Parent 1: Rr (heterozygous rough coat)
Parent 2: Rr (heterozygous rough coat)
By creating a Punnett square, we can analyze the possible genotypes and phenotypes of the offspring:
| R r
-----------
R | RR Rr
-----------
r | Rr rr
Based on the Punnett square, we observe that there are a total of four possible genotypes (two RR and two Rr). Out of these four possibilities, two have the recessive allele for smooth coat (rr). Therefore, the probability that the offspring will have a smooth coat is 2/4, which can be simplified to 1/2 or 50%.
To determine the probability of the offspring having a smooth coat, we need to use Punnett squares, which are a visual representation of the possible combinations of alleles from both parents.
Let's represent the alleles for a rough coat and a smooth coat as follows:
- Allele for rough coat (dominant): R
- Allele for smooth coat (recessive): r
Since both parent guinea pigs are heterozygous (Rr) for a rough coat, their genotypes can be shown as follows:
Parent 1: Rr
Parent 2: Rr
To create a Punnett square, we need to cross the alleles from both parents. Each parent can pass down either the R or r allele to their offspring.
| R | r
---|---|---
R | RR | Rr
r | Rr | rr
In the resulting Punnett square above, each box represents a possible combination of alleles that the offspring can inherit.
From the Punnett square, we see that there are 4 potential outcomes:
- RR (rough coat)
- Rr (rough coat)
- Rr (rough coat)
- rr (smooth coat)
Out of these 4 possibilities, only 1 includes the rr combination, which represents a smooth coat. Therefore, the probability of the offspring having a smooth coat is 1 out of 4, which can also be expressed as 1/4 or 25%.