In your effort to understand what may be wrong with individuals carrying a mutan
ID: 257686 • Letter: I
Question
In your effort to understand what may be wrong with individuals carrying a mutant pretendin gene, you decide to try a little bioinformatics.
With the help of a computer program that allows you to compare a protein sequence to all other known protein sequences to find regions of high similarity between them, you find that pretendin is very similar to another protein called madeupin, which binds to kinetochores in mitotic chromosomes. Furthermore, you discover that the now famous L>E pretendin mutation that you've been investigating so far happens within an amino acid sequence of pretendin that is almost identical to a region of madeupin known to be critical for its ability to bind kinetochores and facilitate the latching of spindle microtubules to chromosomes.
In 150 words or fewer, formulate a hypothesis addressing the following points:
-Where do you think we might see normal pretendinmolecules if we probed for them in cells that are in the G1, metaphase and anaphase phases of the cell cycle? How could the distribution of mutant pretendin be different from that of normal pretendin?
-What could happen to the chromosomes of cells with mutant pretendin during mitosis?
Explanation / Answer
Hypothesis: Pretendin protein is important for the kinetochores microtubules to efficiently bind to the chromosomes during the chromosome division in the G1 phase. These pretendin molecules would be found in the metaphase stage when the chromsomes are condensed into sister chromatids near the spindle equator and during the anaphase these sister chromatids are separated and pulled to the poles. Pretendin molecules help in the tethering and separation of the sister chromatids. When cells expressing the mutant Pretendin protein, during the mitosis process the sister chromatids would remain at the equator during the anaphase.