What is an Endocycle?
The endocycle is a common cell cycle variant in which cells successively duplicate genomic DNA without segregating their chromosomes during mitosis.
What are polyploid giant cancer cells?
Those large and danger cells are recognized as polyploid giant cancer cells (PGCCs). Such cells are under suspicion of being highly related to tumor recurrence and metastasis after treatment and can bring new targets for cancer therapy.
Are humans polyploidy?
Humans. True polyploidy rarely occurs in humans, although polyploid cells occur in highly differentiated tissue, such as liver parenchyma, heart muscle, placenta and in bone marrow. Aneuploidy is more common.
What human cells are polyploid?
In humans, polyploid cells are found in critical tissues, such as liver and placenta. A general term often used to describe the generation of polyploid cells is endoreplication, which refers to multiple genome duplications without intervening division/cytokinesis.
How does endoreduplication work?
Endoreplication occurs when a cell exits the mitotic cell cycle in G2 phase and undergoes multiple S phases without entering mitosis and undergoing cytokinesis. The result is a giant cell with a single, enlarged, polyploid nucleus.
What is the role of endoreduplication?
Endoreduplication is the major source of endopolyploidy in higher plants. The process of endoreduplication results from the ability of cells to modify their classical cell cycle into a partial cell cycle where DNA synthesis occurs independently from mitosis.
Is polyploidy fatal?
Interestingly, polyploidy is lethal regardless of the sexual phenotype of the embryo (e.g., triploid XXX humans, which develop as females, die, as do triploid ZZZ chickens, which develop as males), and polyploidy causes much more severe defects than trisomy involving the sex chromosomes (diploids with an extra X or Y …
What are the benefits of being polyploid?
There are three obvious advantages of becoming polyploid: heterosis, gene redundancy (a result of gene duplication) and asexual reproduction. Heterosis causes polyploids to be more vigorous than their diploid progenitors, whereas gene redundancy shields polyploids from the deleterious effect of mutations.
Is polyploidy lethal in humans?
What is polyploidy what cause it?
Polyploids arise when a rare mitotic or meiotic catastrophe, such as nondisjunction, causes the formation of gametes that have a complete set of duplicate chromosomes. Diploid gametes are frequently formed in this way.
What causes endoreduplication?
Endoreplication, in a broad sense, is a consequence of a cell division block in the presence of an active cell cycle, and it typically occurs as cells differentiate terminally to fulfill a specialised function.
What is produced by endoreduplication?
Endoreduplication occurs when a cell undergoes extra rounds of DNA synthesis (S-phase) without any mitosis or cytokinesis to produce an endopolyploid cell. This produces multiple chromatids of each chromosome.