Question

Unequal crossing over during Prophase I can result in one sister chromosome with a deletion and another with a duplication. A mutated form of hemoglobin, known as hemoglobin Lepore, is known in the human population. Hemoglobin Lepore has a deleted set of amino acids. If it was caused by unequal crossing over, what would be an expected consequence?

Answer 1

Unequal crossing over during Prophase I can result in one sister chromosome with a deletion and another with a duplication. A mutated form of hemoglobin, known as hemoglobin Lepore, is known in the human population. Hemoglobin Lepore has a deleted set of amino acids. If it was caused by unequal crossing over, what would be an expected consequence?

A) There should also be persons whose hemoglobin contains two copies of the series of amino acids that is deleted in hemoglobin Lepore.

B) Each of the genes in the hemoglobin gene family must show the same deletion.

C) The deleted gene must have undergone exon shuffling.

D) The deleted region must be located in a different area of the individual's genome.

Answer:

A) There should also be persons whose hemoglobin contains two copies of the series of amino acids that is deleted in hemoglobin Lepore.

Explanation:

The process of crossing over generates recombinant chromatids that carry the exchanged genetic segments. In case of unequal crossing over, a part of the genetic segment is missing from one recombinant chromatid of a homologous chromosome and is inserted into the recombinant chromatid of the corresponding homologous chromosome. The gamete that obtains the chromosome with an additional genetic segment would give rise to a person carrying the duplicated amino acids that are otherwise missing from the chromosome of the person expressing hemoglobin Lepore.