User:ManjunathaSanka/Sandbox

--ManjunathaSanka (talk) 06:20, 19 September 2014 (UTC)manjunathaStages of Prophase-1 of Meiosis-I
 * Leptotene
 * Zygotene
 * Pachytene
 * Diplotene
 * Diakinesis

Leptotene 1. Chromosomes are thin, long & uncoiled. 2. Each is a doublr chromosomes consisits of two chromatids. 3. each chromosome appear as a string of beads.

Zygotene 1. Homologous chromosomes undergo pairing., this is called Synapsis. 2. The paired Homologous chromosomes are called Bivalents. 3. Each bivalent has 4 chromatids, so they are Tetrads.

Pachytene 1. Here pairing is complete. 2. Coiling takes place b/w non-sister chromatids of tetrad & segments are Exchanged. this process is called as Genetic crossing over. 3. Recombination of genes takesplace. 4. Crossing over takes place by breakage and reunion of Chromatid segments. 5. The point of interchange are X-shaped & are called Chiasmata.

Diplotene 1. Chromosomes show high degree of condensation 2. The attraction b/w homologous chromosomes dissapears & repulsion starts. 3. Each tetrad now appears in different shapes i.e., X, 8, O shaped 4. Repulsion results in Terminalistaion of Chiasmata.

Diakinesis 1. The chiasmata dissapears slowly as paired chromosome begin to separate. 2. The nucleolus breakdown and dissapear. 3. Spindle fibre appears. 4. Nuclear membrane breaks down & chromosomes are released into cytoplasm.

Followed By Metaphase-I, Anaphase-I, Telophase-I