Search results
Results from the WOW.Com Content Network
Prophase II of meiosis is very similar to prophase of mitosis. The most noticeable difference is that prophase II occurs with a haploid number of chromosomes as opposed to the diploid number in mitotic prophase. [12] [10] In both animal and plant cells chromosomes may de-condense during telophase I requiring them to re-condense in prophase II.
Four phases of mitosis: prophase, metaphase, anaphase, and telophase: Prophase: Chromatin into chromosomes, the nuclear envelope breaks down, chromosomes attach to spindle fibers by their centromeres. Metaphase: Chromosomes line up along the metaphase plate (center of the cell). Anaphase: Sister chromatids are pulled to opposite poles of the cell.
The first stage of prophase I is the leptotene stage, also known as leptonema, from Greek words meaning "thin threads". [18]: 27 In this stage of prophase I, individual chromosomes—each consisting of two replicated sister chromatids—become "individualized" to form visible strands within the nucleus.
Meiotic sex chromosome inactivation only happens in male, which may partially be the reason why only Spo11 mutant spermatocytes but not oocytes fail to transition from prophase I to metaphase I. [3] [8] However the asynapsis does not happen only within sex chromosomes, and such transcription regulation was suspended until it was further ...
Using different types of genetic studies, it has been established that diverse kinds of defects are able to activate the SAC: spindle depolymerization, [8] [9] the presence of dicentric chromosomes (with two centromeres), [10] centromeres segregating in an aberrant way, [11] defects in the spindle pole bodies in S. cerevisiae, [12] defects in ...
These chromosomes (paired chromatids) then pair with the homologous chromosome (also paired chromatids) present in the same nucleus (see prophase I in the meiosis diagram). The process of alignment of paired homologous chromosomes is called synapsis (see Synapsis). During synapsis, genetic recombination usually occurs.
During the leptotene stage, the duplicated chromosomes - each consisting of two sister chromatids - condense from diffuse chromatin into long, thin strands that are more visible within the nucleoplasm (nucleus contents). The chromosomes become visible as thin threadlike structures known as leptonema under a light microscope. [1]: 27 [2]: 353
The pachytene stage (/ˈpækɪtiːn/ PAK-i-teen; from Greek words meaning "thick threads". [1]: 27 ), also known as pachynema, is the third stage of prophase I during meiosis, the specialized cell division that reduces chromosome number by half to produce haploid gametes.