Identifying Mitosis
Consider what happens in mitosis. Mitosis is the process of creating diploid cells. Without mitotic replication, your body would not be able to heal itself, or even grow. When mitosis happens, your DNA replicates itself. During mitosis, your cells divide and they also exhibit clear phases, which are called interphase, prophase, metaphase, anaphase, and telophase. The basic process of mitosis is as follows: First, the DNA condenses into chromosomes and the chromosomes align. Then, the daughter chromosomes are pulled apart and they move to the cell poles (the edges of the cell). Last, the cell splits in 2 separate cells, which is also known as cytokinesis.
Count the number of divisions. In mitosis, the cells will only divide once. These post-division cells are called daughter cells. Most human cells divide by splitting into 2 new cells. Check the number of daughter cells. In mitosis, there should only be 2. The parent cell will be gone after mitosis has occurred.
Make sure there is a complete set of chromosomes. The 2 daughter cells will have the same amount and type of chromosomes as the parent nucleus. If the cell does not have a complete set of chromosomes, then it has not completed mitosis, or it has been damaged. Each healthy human somatic cell should have a complete set of chromosomes. The cells that have too few or too many chromosomes will not function well, such as by dying or becoming cancerous.
Identifying Meiosis
Consider how gametes are produced in meiosis. Meiotic replication is responsible for an organism’s ability to reproduce half the number of cells as the daughter cells have, also known as haploid cells. When an organism reproduces, it makes gametes. These cells do not have complete sets of DNA. They have half the number of chromosomes as cells produced in mitotic replication. For example, the meiotic sperm and egg cells each bring half a full set of chromosomes. Pollen is a gamete. Like human gametes, it carries half the number of chromosomes as other plant cells.
Watch for synapsis. Synapsis describes the process that 2 chromosomal pairs use to share and exchange DNA. This process is a part of meiosis, but not a part of mitosis, so it should help you to distinguish the 2 processes. Synapsis is when 2 ends of chromosomes meet and share genetic information with each other. After the cells separate, the genetic information will be mingled in 2 of the 4 cells. This happens during prophase 1 of meiosis. This process is not the same as chromosomal crossover, where homologous chromosomes exchange genetic material.
Count the number of divisions in meiosis. In meiosis, the cell divides more than it does in mitosis. This is crucial to the production of gametes. Because gametes need to have half the number of chromosomes as normal cells, cells divide twice in meiotic reproduction, which is known as Meiosis I and Meiosis II. This means that each phase 1 might find in mitosis is found twice in meiosis: First, the DNA replicates, just like it does in mitosis. Then, 1 cell divides into 2 cells, which also looks the same as it does with mitosis. The homologous pairs divide in the first round of cell divisions (Meiosis I). Then, the sister chromatids divide again in the second round (Meiosis II). Last, the 2 cells divide again. This third cell division is not present in mitosis, so it should help you to tell the difference between mitosis and meiosis.
Check the number of daughter cells. With meiotic cell division, there will be 4, final daughter cells. This number is required to create cells that have half the number of chromosomes that the parent cells did. Without these chromosomes, the gametes would not be able to perform sexual reproduction. For example, when the sperm and egg (haploid cells) meet, they form a complete diploid cell.
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