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Question
Lampbrush chromosomes in shark oocytes occur during which of the following stage?
Lampbrush chromosomes in shark oocytes occur during which of the following stage?
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Solution
The correct option is D Diplotene
Lampbrush chromosomes are a special form of chromosome found in the growing oocytes (immature eggs) of most animals, except mammals. They were first described by Walther Flemming in 1882. Lampbrush chromosomes of tailed and tailless amphibians, birds and insects are described best of all. Chromosomes transform into the lampbrush form during the diplotene stage of meiotic prophase I due to an active transcription of many genes. They are highly extended meiotic half-bivalents, each consisting of 2 sister chromatids.
A given loop always contains the same DNA sequence, and it remains extended in the same manner as the oocytes grows. These chromosomes are producing large amounts of RNA for the oocyte, and most of the genes present in the DNA loops are being actively expressed. Each lateral loop contains one or several transcription units with polarized RNP-matrix coating the DNA axis of the loop. The majority of the DNA, however, is not in loops but remains highly condensed in the chromomeres on the axis, where genes are generally not expressed.
Lampbrush chromosomes are a special form of chromosome found in the growing oocytes (immature eggs) of most animals, except mammals. They were first described by Walther Flemming in 1882. Lampbrush chromosomes of tailed and tailless amphibians, birds and insects are described best of all. Chromosomes transform into the lampbrush form during the diplotene stage of meiotic prophase I due to an active transcription of many genes. They are highly extended meiotic half-bivalents, each consisting of 2 sister chromatids.
A given loop always contains the same DNA sequence, and it remains extended in the same manner as the oocytes grows. These chromosomes are producing large amounts of RNA for the oocyte, and most of the genes present in the DNA loops are being actively expressed. Each lateral loop contains one or several transcription units with polarized RNP-matrix coating the DNA axis of the loop. The majority of the DNA, however, is not in loops but remains highly condensed in the chromomeres on the axis, where genes are generally not expressed.
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