Describe the chromosomal events during Leptotene and Zygotene stage of Meiosis prophase-I.
Answers
Explanation:
The leptotene stage, also known as the leptonema, is the first of five substages of prophase I in meiosis. The term leptonema derives from Greek words meaning "thin threads".[1]:27 A cell destined to become a gamete enters the leptotene stage after its chromosomes are duplicated during interphase. During the leptotene stage those duplicated chromosomes—each consisting of two sister chromatids—condense from diffuse chromatin into long, thin strands that are more visible within the nucleoplasm. The next stage of prophase I in meiosis is the zygotene stage.[1]:27[2]:353
During this stage, the chromosomes attach themselves by their ends (telomeres) to the inner membrane of the nuclear envelope. At the transition to the zygotene stage the telomeres usually aggregate at a nuclear envelope sector, thereby forming a meiotic bouquet.[3] Lateral (axial) elements of the synaptonemal complex are also formed. It is the first stage of Prophase 1 in Meiosis 1.
1 ) Leptotene – The chromosomes begin to condense and attain a compact structure during leptotene.
2 ) Zygotene – In zygotene, the pairing of homologous chromosomes starts a process known as chromosomal synapsis, accompanied by the formation of a complex structure called synaptonemal complex. A pair of synapsed homologous chromosome forms a complex known as bivalent or tetrad.