An animal heterozygous for a reciprocal balanced translocation...

Question

An animal heterozygous for a reciprocal balanced translocation has the following chromosomes:

MN • OPQRST

MN • OPQRjkl

cdef • ghijkl

cdef • ghiST

Among the three segregation patterns, which is least likely to occur? Why?

Accepted Answer

Welcome back, everyone. Here's your next question. Which of the following statements regarding balanced reciprocal transcations is incorrect. Choice. A it occurs with the displacement of the end regions of the chromosomes B. They result in a gain or loss of genetic material C, they are usually harmless as they do not result in a gain or loss of genetic material or d none of these. So let's think about balanced reciprocal transcations. We're calling two important things. We're looking for an incorrect or untrue statement and we have that choice. Dean, none of these mean. So there's a possibility that none of A B or C will be incorrect. So we can recall that a translocation is when you have the transfer of genetic material to a non homologous chromosome. So it's not recombination where you have swapping of material between the homologous pairs, but the transfer of a piece of one chromosome to a non homologous chromosome. But we're looking at a specific kind of translocation, balanced and reciprocal. So by reciprocal, we mean two chromosomes swap material, there's an exchange between the non homologous chromosomes with material from one going to a second and vice versa. And then balanced, meaning that no genetic material is gained or lost in the process. So you don't have any uh incidental duplication of genes or deletion of genes. So with all this in mind of our, what kind of translocation we're talking about? Let's look through our answer choices calling that we're looking for an incorrect and untrue statement. So choice A says it occurs with the displacement of the end regions of the chromosomes. While this is true, since we're talking about a balanced swapping of material, switching of equal portions, it does occur with the displacement of those end regions of two chromosomes. So that's not our answer. Since we're looking for an untrue statement. Choice B says they result in a gain or loss of genetic material. Well, this one is incorrect. So we're going to go ahead and select that as our answer. This is incorrect because we have a balanced translocation. So that means there is no gain or loss of genetic material. So we can also eliminate choice D none of these since we do have an incorrect answer. And then finally, choice C are usually harmless as they do not result in a gain or loss of genetic material. Yes, that is true. They do not cause a phenotypic effect on the individual that has one of these since they have all the genes they're supposed to have. So choice C is not our answer. Uh One little note here is that it can affect progeny because since you've swapped those two bits of material that can cause unbalanced changes in, in the gametes of that particular individual that could result in stillbirth, miscarriage or chromosomal defects on the offspring. But it won't have a phenotypic effect on the person carrying that balanced reciprocal translocation themselves. So again, which of the following statements regarding balanced reciprocal transcations is incorrect and that is choice B they result in a gain or loss of genetic material. See you in the next video.

An animal heterozygous for a reciprocal balanced translocation has the following chromosomes:
MN • OPQRST
MN • OPQRjkl
cdef • ghijkl
cdef • ghiST
Among the three segregation patterns, which is least likely to occur? Why?

Key Concepts

Heterozygous Reciprocal Balanced Translocation

Segregation Patterns

Viability of Gametes

Watch next