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The best characterized point centromeres are those of the budding yeast, Saccharomyces cerevisiae. "Regional centromeres" is the term coined to describe most centromeres, which typically form on regions of preferred DNA sequence, but which can form on other DNA sequences as well.
If the chromosome is a submetacentric chromosome (One arm big and the other arm small) then the centromere divides each chromosome into two regions: the smaller one, which is the p region, and the bigger one, the q region. The sister chromatids will be distributed to each daughter cell at the end of the cell division.
The result is the production of four haploid cells (n chromosomes; 23 in humans) from the two haploid cells (with n chromosomes, each consisting of two sister chromatids) [clarification needed] produced in meiosis I. The four main steps of meiosis II are: prophase II, metaphase II, anaphase II, and telophase II.
Three types of cell division: binary fission (taking place in prokaryotes), mitosis and meiosis (taking place in eukaryotes).. When cells are ready to divide, because cell size is big enough or because they receive the appropriate stimulus, [20] they activate the mechanism to enter into the cell cycle, and they duplicate most organelles during S (synthesis) phase, including their centrosome.
A karyogram or idiogram is a graphical depiction of a karyotype, wherein chromosomes are generally organized in pairs, ordered by size and position of centromere for chromosomes of the same size. Karyotyping generally combines light microscopy and photography in the metaphase of the cell cycle , and results in a photomicrographic (or simply ...
Meiosis only occurs in cells of the sex organs, and serves the purpose of generating haploid gametes such as sperm, eggs, or spores, which are later fused during fertilization. The two meiotic divisions, known as Meiosis I and Meiosis II, may also include various genetic recombination events between homologous chromosomes. meiotic spindle
The anchorage of the cytoskeleton to the chromosomes takes place at the centromere thanks to a protein complex called kinetochore. This tension results in the alignment of the bivalent at the center of the cell, the chiasmata and the distal cohesion of the sister chromatids being the anchor point sustaining the force exerted on the whole structure.
(4) Long (q) arm In genetics , a locus ( pl. : loci ) is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. [ 1 ] Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of protein-coding genes in a complete haploid set of 23 ...