meiosis is not at all optimized to create new gene combinations, as Holliday junctions can be resolved with and without cross-over. The frequencies of non-crossovers were shown to be higher than those of cross-overs, but only the latter create new gene combinations in flanking regions, which ...
Bellou et al. show that acrocentric chromosomes, such as chromosome 21, are more prone to aneuploidy in oocytes due to their unique architecture and lower cohesion levels, which lead to inefficient alignment and increased mis-segregation during meiosis. ...
A type of cell division, occurring in two phases, that reduces the number of chromosomes in reproductive cells to half the original number. It results in the production of reproductive cells (called gametes) in animals and the formation of spores in plants, fungi, and most algae. The first ...
In budding yeast, a complex known as monopolin was identified, which ensures the monopolar attachment of kinetochores during meiosis I. The existence of two consecutive chromosome-segregation events during meiosis, without an intervening S phase, requires specialization of cell-cycle controls to execute...
The process by which the two copies of a given gene are distributed into separate gametes is referred to as segregation. Thus, if an individual is heterozygous at the A gene for two different alleles, A and a, his or her gametes will be equally likely to carry the A allele or the a ...
This not only results in the shuffling of genetic material, but also plays a key role in ensuring proper chromosome segregation. Following recombination, the recombined non-sister chromatids remain linked through structures known as chiasmata. These structures hold the homologs together until anaphase...
synapsis and proper chromosome segregation, and also results in the redistribution of genetic materials, thereby leading to distinct genetic makeup between parents and offsprings and among individual progeny. Plants have many advantages to study meiosis genetically such as ease of access to meiotic cell...
The prerequisite for this segregation of haploid sets is the exact longitudinal pairing between two homologous chromosomes which takes place during early phases of first meiosis. Furthermore, peculiar behavior of the centromere at first meiotic anaphase is required for this segregation. In ordinary ...
In budding yeast, a complex known as monopolin was identified, which ensures the monopolar attachment of kinetochores during meiosis I. The existence of two consecutive chromosome-segregation events during meiosis, without an intervening S phase, requires specialization of cell-cycle controls to execute...
3. Crossing over in foetal oocytes 3.1. Introduction to meiotic recombination Meiotic recombination takes place during foetal stages of oocyte development, and is a key process in enabling the balanced metaphase I segregation of homologous chromosomes in adults. Recombination is initiated by the activity...