Lamp brush chromosomes – Video

Video Link: https://www.youtube.com/watch?v=2jGMEcr2g_4

Lamp brush chromosomes
For more information, log on to- shomusbiology.weebly.com Download the study materials here- shomusbiology.weebly.com Lampbrush chromosomes (first seen by Flemming in 1882) are a special form of chromosomes that are found in the growing oocytes (immature eggs) of most animals, except mammals.[1] Lampbrush chromosomes of tailed and tailless amphibians, birds and insects are described best of all.[2][3][4] 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. Lampbrush chromosomes are clearly visible even in the light microscope, where they are seen to be organized into a series of chromomeres with large chromatin loops extended laterally. Amphibian and avian lampbrush chromosomes can be microsurgically isolated from oocyte nucleus (germinal vesicle) with either forceps or needles.[5][6] 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.[7][8][9] The majority of the DNA, however, is not in loops but remains highly condensed in the chromomeres on the axis, where genes are ...From:Suman BhattacharjeeViews:0 0ratingsTime:04:43More inEducation

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Lamp brush chromosomes - Video