Urgent help genetics!!!?
You have a trihybrid diploid individual of genotype AaBbEe – genes A and B are on the same chromosome while E is on a different chromosome. For this individual assume the following (with lines connecting alleles on the same chromosome): A--B, a--b, E, e.
Which meiotic processes contribute to diversity in the gametes with respect to genes A, B, and E; be specific (which processes impact which genes)? Think: how do you get different combinations of the alleles in the gametes for each pair of genes - for example, Ab versus aB, or BE versus be, and so on?
- jacob sLv 71 month agoFavorite Answer
1. The organism is a Trihybrid - It means it contains two different alleles to three genes AaBbEe. Here 'A' allele is from one plant and 'a' allele from the other. Together combined they became a hybrid. It follows the same for other two genes.
2. The organism is diploid: It means organism carries Two sets of chromosomes. One from the each parent. gamete from the diploid organism is always a haploid or carry one allele.
3. A and B are on the same chromosome: It says that A and B are on the same chromosome, as does a and b. But E and e are on different chromosomes.
The type of gametes produced from AaBbCc with the above conditions are as follows :
There are two cases :
Case 1. If there is no crossing over between the chromosomes A-B and a-b. The gametes obtained are as follows :
gametes E e
A-B ABE ABe
a-b abe abe
Box:The box depicts segregation of chromosomes
Case 2: If there is crossing over between chromosome A-B and a-b. then rearranged chromosomes will be A-b, a-B and the gametes produced are as follows :
gametes E e
A-b AbE Abe
a-B aBE aBe
Box: The box depicts segregation of chromosomes
So, the possible gametic configuration that can be obtained in total will be :
ABE, ABe, abe, AbE, aBE, Abe, aBe.
Now let's validate the options :
a. AaBbEe - not possible as the gamete cannot be in diploid condition. so this cannot exist and the right option.
b.ABEe - not possible as the gamete will carry one gene that is either E or e. so this cannot exist and the right option.
c.Abe - If crossing over occurs this gamete can occur. Hence this is a possible condition and not the right option.(ABE, ABe, abe, AbE, aBE, Abe, aBe.)
d.AAbbEe- not possible as the gamete cannot be in diploid condition. so this cannot exist and the right option.
e.aBE- If crossing over occurs this gamete can occur. Hence this is a possible condition and not the right option.(ABE, ABe, abe, AbE, aBE, Abe, aBe.)
Therefore option a,b,d is the correct answer.
- JazSincLv 71 month ago
1. You can get A--b and a--B from crossover in meiosis I.
2. Disregarding crossover for a moment, you can get ABE and ABe gametes from segregation in anaphase I.
3. Put 'em all together. With various crossover and segregation, you can get these gametes: