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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.
The function or significance of mitosis, is the maintenance of the chromosomal set; each formed cell receives chromosomes that are alike in composition and equal in number to the chromosomes of the parent cell. Mitosis occurs in the following circumstances: Development and growth: The number of cells within an organism increases by mitosis.
Interphase is the process through which a cell must go before mitosis, meiosis, and cytokinesis. [15] Interphase consists of three main phases: G 1, S, and G 2. G 1 is a time of growth for the cell where specialized cellular functions occur in order to prepare the cell for DNA replication. [16]
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.
Mitosis divides the chromosomes in a cell nucleus. During mitosis chromosome segregation occurs routinely as a step in cell division (see mitosis diagram). As indicated in the mitosis diagram, mitosis is preceded by a round of DNA replication, so that each chromosome forms two copies called chromatids.
Preprophase is an additional phase during mitosis in plant cells that does not occur in other eukaryotes such as animals or fungi. It precedes prophase and is characterized by two distinct events: The formation of the preprophase band, a dense microtubule ring underneath the plasma membrane. The initiation of microtubule nucleation at the ...
Crossing over occurs between prophase I and metaphase I and is the process where two homologous non-sister chromatids pair up with each other and exchange different segments of genetic material to form two recombinant chromosome sister chromatids. It can also happen during mitotic division, [1] which may result in loss of heterozygosity.
The G1/S transition occurs late in G1 and the absence or improper application of this highly regulated checkpoint can lead to cellular transformation and disease states such as cancer. [ 4 ] [ 1 ] During this transition, G1 cyclin D -Cdk4/6 dimer phosphorylates retinoblastoma releasing transcription factor E2F , which then drives the transition ...