Hello, can you please explain to me how to solve these problems, thanks for your
ID: 58632 • Letter: H
Question
Hello, can you please explain to me how to solve these problems, thanks for your help
A pregnant couple is seeking genetic counselling after their first born had a genetic disorder. Cytogenetic testing on the parents and the fetus showed the only variation of interest to be located on chromosome 1 and relates to genes A, B, C, D, E, F, and G. Below are the chromosome 1 genotypes of the parents and the fetus [ represents the centromere). Explain how the fetus could get the above genotype? Should the parents be worried about any abnormalities? Is it likely that their future children will have the same genotype? Chromosome Structural Evolution: Predict the order in which the following chromosomal changes may have happened starting from ABCD EFGH ( represents the centromere). Explain what structural change may have happened at each stage.Explanation / Answer
12. Yes. we can observe an extra gene on the chromosomes, and the fetus 1 is carrying abnormal chromosome. These type of errors generally ocur due to chromosomal nondisjunctioning.
During meiosis, the homologous chromosomes align during the prophase. These chromosomes crossover at some point and rejoin to form recombinant chromatids, and move towards the opposite poles during anaphase.
Sometimes, error occurs in meiosis during the meiosis – I, i.e. during the separation of homologous chromosomes. These errors result in excess or less chromosomes in the daughter cell, and this is called “nondisjunctioning.”
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