Contrast telophase in plant and animal mitosis.
In this exercise, we need to compare telophase in plant and animal mitosis.
An interesting procedure has been applied for assessing the chromosomal balance of potential secondary oocytes for use in human in vitro fertilization. Using fluorescence in situ hybridization (FISH), Kuliev and Verlinsky (2004) were able to identify individual chromosomes in the first polar bodies and thereby infer the chromosomal makeup of “sister” oocytes.
(a) Assume that when examining a first polar body you saw that it had one copy (dyad) of each chromosome but two dyads of chromosome 21. What would you expect to be the chromosomal 21 complements in the secondary oocyte? What consequences are likely in the resulting zygote, if the secondary oocyte was fertilized?
(b) Assume that you were examining a first polar body and noted that it had one copy (dyad) of each chromosome except chromosome 21. Chromosome 21 was completely absent. What would you expect to be the chromosome 21 complement (only with respect to chromosome 21) in the secondary oocyte? What consequences are likely in the resulting zygote if the secondary oocyte was fertilized?
(c) Kuliev and Verlinsky state that there was a relatively high number of separation errors at meiosis I. In these cases, the centromere underwent a premature division, occurring at meiosis I rather than meiosis II. Regarding chromosome 21, what would you expect to be the chromosome 21 complement in the secondary oocyte in which you saw a single chromatid (monad) for chromosome 21 in the first polar body? If this secondary oocyte was involved in fertilization, what would be the expected consequences?