Meiosis
Meiosis is the process in which one cell divides into 4 cells, called gametes, better know as sex cells. Each of the 4 gamete cells created has half of the normal amount of chromosomes (haploid) as the original cell (diploid) was divided 4 times. These sex cells (sperm or egg) are then joined to form offspring with their genetic material a mix of both parents. This process allows for genetic disorders, like hemochromatosis, to be passed on to offspring. If a parent has the hemochromatosis gene in their DNA, the haploid cells they produce will have it too, allowing the child to possibly inherit it. Learn more about the chances that a parent can give hemochromatosis to their children in the probability section. Meiosis is normally divided into multiple stages.
Interphase: Though not a true part of meiosis, interphase refers to the time period where the cell is growing and performing normal functions. During this time, the cell has 46 chromosomes.
Prophase I: The first stage of meiosis. During this phase, the cell duplicates its chromosome number to 92 (46 homologous pairs). This stage is also where crossing over occurs. Crossing over is when 2 chromosomes switch the bottom genetic material with one another. This process assures that each sex cell is unique. The 2 centrosomes inside the cell containing centrioles begin to create spindle or microtubules between one another which will be used in the later stages.
Metaphase I: This phase consists of all 92 chromosomes lining up in the middle of the cell end to end. Here, microtubules attach themselves to the centromeres of each of the homologous pairs of chromosomes.
Anaphase I: The homologous pairs of chromosomes are separated and are pulled to opposite poles within the cell while keeping the sister chromosomes together.
Telophase I: Microtubules disappear and cell division begins. Two nuclei form around the chromosome groupings.
Cytokinesis: A new membrane forms between the two groupings of chromosomes. This process produces 2 distinct and new cells.
Prophase II: New microtubules begin to form in each of the two new cells. Unlike prophase I, the chromosomes are not duplicated in this process.
Metaphase II: The 46 chromosomes in each cell line up at the equator end to end. Microtubules attach themselves to the middle of each chromosome.
Anaphase II: The sister chromatids are pulled to opposite ends of the cell because of the microtubule fibers. The separated chromatids are now individual chromosomes.
Telophase II: The chromosomes continue to move to the poles in each of the 2 cells. New nuclei form around each of the chromosome groupings.
Cytokinesis: Cells pinch the two nuclei apart and form new membranes. This process is done in each of the 2 cells, creating 4 cells total. These 4 cells are haploids containing 23 individual chromosome halves that need a sex cell from the other gender to form a complete diploid number and form offspring.
Meiosis Diagram:
Interphase: Though not a true part of meiosis, interphase refers to the time period where the cell is growing and performing normal functions. During this time, the cell has 46 chromosomes.
Prophase I: The first stage of meiosis. During this phase, the cell duplicates its chromosome number to 92 (46 homologous pairs). This stage is also where crossing over occurs. Crossing over is when 2 chromosomes switch the bottom genetic material with one another. This process assures that each sex cell is unique. The 2 centrosomes inside the cell containing centrioles begin to create spindle or microtubules between one another which will be used in the later stages.
Metaphase I: This phase consists of all 92 chromosomes lining up in the middle of the cell end to end. Here, microtubules attach themselves to the centromeres of each of the homologous pairs of chromosomes.
Anaphase I: The homologous pairs of chromosomes are separated and are pulled to opposite poles within the cell while keeping the sister chromosomes together.
Telophase I: Microtubules disappear and cell division begins. Two nuclei form around the chromosome groupings.
Cytokinesis: A new membrane forms between the two groupings of chromosomes. This process produces 2 distinct and new cells.
Prophase II: New microtubules begin to form in each of the two new cells. Unlike prophase I, the chromosomes are not duplicated in this process.
Metaphase II: The 46 chromosomes in each cell line up at the equator end to end. Microtubules attach themselves to the middle of each chromosome.
Anaphase II: The sister chromatids are pulled to opposite ends of the cell because of the microtubule fibers. The separated chromatids are now individual chromosomes.
Telophase II: The chromosomes continue to move to the poles in each of the 2 cells. New nuclei form around each of the chromosome groupings.
Cytokinesis: Cells pinch the two nuclei apart and form new membranes. This process is done in each of the 2 cells, creating 4 cells total. These 4 cells are haploids containing 23 individual chromosome halves that need a sex cell from the other gender to form a complete diploid number and form offspring.
Meiosis Diagram:
Mitosis
Once one single zygote is formed by the joining of two individual gamete cells, this zygote must copy itself to grow. Unlike meiosis which forms 4 unique haploid cells, mitosis will produce 2 identical diploid autosomal (body) cells. This ensures that the growing individual will have the same genetic information throughout its entire body. Cells must have the correct amount of chromosomes to copy itself as the process of growth or replacement never stops. Mitosis is the process in which an inherited hemochromatosis gene from a parent can be present throughout all of the cells within someone's body. The gene is replicated over and over to form new cells, a process that starts as a single zygote cell. New cells only can form from old ones which formed from the disorder ridden original zygote cell.
Interphase: Though not a true part of mitosis, interphase refers to the time period where the cell is growing and performing normal functions. In this time, the cell has 46 chromosomes.
Prophase I: The first stage of mitosis. During this phase, the cell duplicates its chromosome number to 92 (46 homologous pairs). Unlike meiosis, crossing over does not occur as the end goals is to have identical cells, not unique ones. The 2 centrosomes inside the cell containing centrioles begin to create spindle or microtubules between one another which will be used in the later stages.
Metaphase I: This phase consists of all 92 chromosomes lining up in the middle of the cell end to end. Microtubules attach themselves to the centromeres of each of the homologous pairs of chromosomes.
Anaphase I: The sister chromatids are separated and are pulled to opposite poles within the cell.
Telophase I: Microtubules disappear and cell division begins. Two nuclei form around the chromosome groupings.
Cytokinesis: A new membrane forms between the two groupings of chromosomes. This process produces 2 identical cells.
Mitosis Diagram:
Interphase: Though not a true part of mitosis, interphase refers to the time period where the cell is growing and performing normal functions. In this time, the cell has 46 chromosomes.
Prophase I: The first stage of mitosis. During this phase, the cell duplicates its chromosome number to 92 (46 homologous pairs). Unlike meiosis, crossing over does not occur as the end goals is to have identical cells, not unique ones. The 2 centrosomes inside the cell containing centrioles begin to create spindle or microtubules between one another which will be used in the later stages.
Metaphase I: This phase consists of all 92 chromosomes lining up in the middle of the cell end to end. Microtubules attach themselves to the centromeres of each of the homologous pairs of chromosomes.
Anaphase I: The sister chromatids are separated and are pulled to opposite poles within the cell.
Telophase I: Microtubules disappear and cell division begins. Two nuclei form around the chromosome groupings.
Cytokinesis: A new membrane forms between the two groupings of chromosomes. This process produces 2 identical cells.
Mitosis Diagram: