You are working with human cells cultured in your laboratory, and you have devel
ID: 97650 • Letter: Y
Question
You are working with human cells cultured in your laboratory, and you have developed cells that have a nonfunctioning gene for the Bub protein. Predict what would happen in these cells. Securin would not get ubiquitylated, the chromosomes would not separate, and the cell would stall in Metaphase. Cdc20 would not be released and APC would not be active, stalling the cell at the Metaphase-Anaphase transition. The mitotic spindle would not attach to the sister chromatics and the cell would stall in Prophase. The Anaphase Promoting Complex would be inappropriately activated and chromatics might not attach to the spindle apparatus, resulting in nondisjunction.Explanation / Answer
BUB1 (budding uninhibited by benzimidazoles) is an enzyme coded by the BUB1 gene. It is also known as mitotic checkpoint serine/ threonine protein kinase. This protein is attached to the kinetochores and plays an important role in the establishment of mitotic spindle checkpoint. Therefore BUB1 is also known as Mitotic spindle checkpoint kinase which is conserved in various organisms like Saccharomyces cerevisae and humans.
Mitosis is a complex process which involves many cytoplasmic and nuclear events can be divided into different stages like prophase, prometaphase, metaphase, anaphase and telophase.
During mitosis if there is any mis separation or premature separation of the sister chromatids it will lead to either loss or gain of chromosomes. This is sometimes called as non- disjunction of chromosome. This results in aneuploidy which is a serious chromosomal instability like in Downs Syndrome.
Therefore the option is D. The Anaphase promoting complex would be inappropriately activated and chromatids might not attach to the spindle apparatus resulting in nondisjunction.
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