Ad
related to: cells that replicate dna and chromosomes occur in different parts
Search results
Results From The WOW.Com Content Network
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
Eukaryotes initiate DNA replication at multiple points in the chromosome, so replication forks meet and terminate at many points in the chromosome. Because eukaryotes have linear chromosomes, DNA replication is unable to reach the very end of the chromosomes. Due to this problem, DNA is lost in each replication cycle from the end of the chromosome.
During the S-phase of each cell cycle (Figure 1), all of the DNA in a cell is duplicated in order to provide one copy to each of the daughter cells after the next cell division. The process of duplicating DNA is called DNA replication, and it takes place by first unwinding the duplex DNA molecule, starting at many locations called DNA ...
The terminal cell elongates more than the deeper cells; then the production of a lateral bisector takes place in the inner fluid, which tends to divide the cell into two parts, of which the deeper one remains stationary, while the terminal part elongates again, forms a new inner partition, and so on.
This results in polyploid cells or, if the chromosomes duplicates repeatedly, polytene chromosomes. [68] [70] Endoreduplication is found in many species and appears to be a normal part of development. [70] Endomitosis is a variant of endoreduplication in which cells replicate their chromosomes during S phase and enter, but prematurely terminate ...
If the cell is not to divide again, it will enter G 0. [3] Synthesis (S), in which the cell synthesizes its DNA and the amount of DNA is doubled but the number of chromosomes remains constant (via semiconservative replication). G 2 (Gap 2), in which the cell resumes its growth in preparation for division. The cell continues to grow until ...
Following chromosomal DNA replication, the blue chromosome is composed of two identical sister chromatids and the pink chromosome is composed of two identical sister chromatids. In mitosis, the sister chromatids separate into the daughter cells, but are now referred to as chromosomes (rather than chromatids) much in the way that one child is ...
Eukaryotic DNA replication requires precise coordination of all DNA polymerases and associated proteins to replicate the entire genome each time a cell divides. This process is achieved through a series of steps of protein assemblies at origins of replication, mainly focusing the regulation of DNA replication on the association of the MCM ...