What is meiosis? What is a cell? What is a stem cell? How helpful was this page? What's the main reason for your rating? Which of these best describes your occupation? What is the first part of your school's postcode? How has the site influenced you or others? After meiosis, the sperm and egg cells can join to create a new organism.
Meiosis is why we have genetic diversity in all sexually reproducing organisms. During meiosis, a small portion of each chromosome breaks off and reattaches to another chromosome. This process is called "crossing over" or "genetic recombination.
The end result of meiosis is four haploid daughter cells that each contain different genetic information from each other and the parent cell. Click for more detail. Meiosis I halves the number of chromosomes and is also when crossing over happens. Meiosis II halves the amount of genetic information in each chromosome of each cell. The end result is four daughter cells called haploid cells.
Haploid cells only have one set of chromosomes - half the number of chromosomes as the parent cell. Before meiosis I starts, the cell goes through interphase. Just like in mitosis, the parent cell uses this time to prepare for cell division by gathering nutrients and energy and making a copy of its DNA.
During the next stages of meiosis, this DNA will be switched around during genetic recombination and then divided between four haploid cells. An estimation of the number of cells in the human body. Original animal cell and E. Coli cell video from National Institute of Genetics via Wikimedia. Shyamala Iyer. Cell Division. Bacterial Cell. Fungal Cell. Plant Cell. By volunteering, or simply sending us feedback on the site. Scientists, teachers, writers, illustrators, and translators are all important to the program.
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When mitosis is not regulated correctly, health problems such as cancer can result. The other type of cell division, meiosis, ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half—from 46 to 23—to form sperm and egg cells.
When the sperm and egg cells unite at conception, each contributes 23 chromosomes so the resulting embryo will have the usual Meiosis also allows genetic variation through a process of gene shuffling while the cells are dividing. Other chapters in Help Me Understand Genetics.
Why is meiosis important? More about meiosis. Genes are packaged differently in mitosis and meiosis — but what is the effect of this difference? What else can go wrong with chromosomes in meiosis? Meiosis is important because it ensures that all organisms produced via sexual reproduction contain the correct number of chromosomes. Meiosis also produces genetic variation by way of the process of recombination. Later, this variation is increased even further when two gametes unite during fertilization, thereby creating offspring with unique combinations of DNA.
This constant mixing of parental DNA in sexual reproduction helps fuel the incredible diversity of life on Earth. Watch this video for a summary of meiosis. Key Questions How did sexual reproduction evolve? What happens when meiosis goes wrong? Key Concepts chromosome meiosis haploid diploid recombination.
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