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Question
please use the link to answer the questions!
https://www.nature.com/scitable/topicpage/dna-deletion-and-duplication-and-the-associated-331
1. What is a chromosomal duplication and why do such duplications adversely affect embryonic development?
2. When does recombination of homologous chromosomes take place? How can duplication events such as that shown in Figure 3 lead to increased genetic diversity and even to the emergence of new species?
3. Explain why low copy repeat (LCR) sequences, like the pericentromeric regions of chromosomes, are often substrates for non-allelic homologous recombination (NAHR). When do such NAHR events lead to inversions and translocations?
4. You are a molecular geneticist. You are attempting to develop a cure for a genetic disorder that results from either a deletion or duplication. Which in your opinion would be the easier of the two conditions to treat? Explain your reasoning.
Explanation / Answer
1). Chromosomal duplication: The chromosomal duplication results in the formation of extra genes in a particular chromosomal region subjected to duplication. So, the number of genes vary from the original chromosome. The chromosomal duplications can be tandem or displaced, depending on their location. This imbalance in the chromosomes or the number of genes results in spontaneous abortion of the fetus. Charcot-Marie-Tooth disease type 1A is one of the diseases caused by chromosomal duplication.
To determine when a particular chromosomal region was duplication, it is required to measure the number of changes in nucleotides present in between the two portions, especially in the regions that are not affected by the natural selection. The frequency of nucleotide divergence is relatively constant, so it can be used as a molecular clock to determine the time, i.e. when did the genomic changes occur.
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