The actual division occurs during the S phase bur the G phases are mainly for the purpose of growing. Starting with the G1 phase the cell grows in preparation for certain intracellular components and DNA replication. This phase makes sure the cell is prepared for the process of DNA replication. It reviews the size and environment to ensure that is it ready to go, and cannot leave the G1 until it is complete. But what happens to a cell when it is not complete and cannot exit out of the phase?
This helps to create genetic diversity. Anaphase 1 is where the bivalents separate and the homologous chromosomes move to opposite poles of the cell. Telophase 1 is where the nuclear envelope reforms after disintegrating in prophase 1. Then cytokinesis is where the cell divides to create two new cells which are haploid (GENIE, 2010). The next main stage is meiosis 2 and this is where each chromosome is split into 2 sister chromatids.
To replicate, the cell goes through cell division. That is also known as mitosis. That is when one parent cell produces two daughter cells. Imagine, what would Earth be without DNA?
Reece, J.B., Urry, L.A., Cain, M.L., Wasserman, S.A., Minorsky, P.V., & Jackson, R.B. (2011). Campbell biology (9th ed.). San Francisco, CA: Pearson Education , Inc. Sharp, D. J., Rogers, G.C., & Scholey, J. M. (2000). Microtubule motors in mitosis.
The G1, G2, and S phase together is known as interphase. Interphase takes place between one mitotic phase and the next. In M phase, the cell divides its copied dna and cytoplasm to make two new cells. It involves two distinct division related processes. Mitosis and cytokinesis.
When development is complete cell division continues as it is essential to survival. In order for cell division to be productive the genetic material and the nucleus must be twinned accurately and one copy must be distributed to each daughter cell. The copying of the cells genetic information is called DNA replication, nuclear division is called mitosis. Throughout the mitotic(M) phase the cell must undergo mitosis, a process that separates the duplicated chromosomes of a cell into two identical nuclei. It then divides to form two new respective cells during cytokinesis.
Nature Education 1(1) Accessed: 02/11/2013 www.nature.com/scitable/topicpage/regulation-of-transcription-and-gene-expression-in-1086 Hartl Daniel L. 2009 Genetics Analysis of Genes and Genomes Added to Library: 18 Nov 2013Last Updated: 18 Nov 2013 View group membership for this record View file attachments View figure attachment Russel Peter J. 2010 iGenetics A molecular approach
c. The creation of genetic variety by crossing over between homologous chromosomes During prophase 1 of meiosis, equal portions of homologous chromosomes may be swapped. In this way new genetic combinations are made and linked genes separated. The variety which meiosis brings vital for to the process of evolution. By providing a varied stock of individuals it allows the natural selection of those best suited to the existing conditions and makes sure that species constantly change and adapt when these conditions change. This is the main biological significance of meiosis.
AG Scientific. AG Scientific. [Online]. ; 2014 [cited 2014 April 19. Available from: www.agscientific.com/molecular-biology/molecular-biology.html.
The last phase of mitosis is telophase. In this final stage, the cells begin to separate and prepare for cytokinesis. The chromosomes return to their original stringy form that they were in interphase and the beginning of prophase and the daughter cells begin to form. Another thing that happens is that two nuclei form on each side of the cell and the chromosomes begin to uncoil.The last step of the cell cycle is cytokinesis. This process is very similar to what happens in telophase.