Mitis Research Paper
MITOSIS
What is Mitosis?
There are various structures within the cell, but many are too difficult to see. For example, within the nucleus lie the chromosomes. These are important for heredity and reproduction. When a cell splits and becomes two, certain processes occur within the nucleus first. One of these processes involves the splitting of the chromosomes. This process is called Mitosis and there are four distinct stages.
Mitosis takes place in Regular Body Cells or Somatic Cell. It keeps Cells Living and Growing.
Events during Mitosis | | Interphase: Cells may appear inactive during this stage, but they are quite the opposite. This is the longest period of the complete cell cycle during which DNA replicates, the centrioles …show more content…
divide, and proteins are actively produced. | | Prophase: During this first mitotic stage, the nucleolus fades and chromatin (replicated DNA and associated proteins) condenses into chromosomes.
Each replicated chromosome comprises two chromatids, both with the same genetic information. Microtubules of the cytoskeleton, responsible for cell shape, motility and attachment to other cells during interphase, disassemble. And the building blocks of these microtubules are used to grow the mitotic spindle from the region of the centrosomes. | | Prometaphase: In this stage the nuclear envelope breaks down so there is no longer a recognizable nucleus. Some mitotic spindle fibers elongate from the centrosomes and attach to kinetochores, protein bundles at the centromere region on the chromosomes where sister chromatids are joined. Other spindle fibers elongate but instead of attaching to chromosomes, overlap each other at the cell center. …show more content…
| | Metaphase: Tension applied by the spindle fibers aligns all chromosomes in one plane at the center of the cell. | | Anaphase: Spindle fibers shorten, the kinetochores separate, and the chromatids (daughter chromosomes) are pulled apart and begin moving to the cell poles. | | Telophase: The daughter chromosomes arrive at the poles and the spindle fibers that have pulled them apart disappear. | | Cytokinesis: The spindle fibers not attached to chromosomes begin breaking down until only that portion of overlap is left. It is in this region that a contractile ring cleaves the cell into two daughter cells. Microtubules then reorganize into a new cytoskeleton for the return to interphase. |
Mitosis Plants vs. Animals
While the main purpose of mitosis remains the same in plants and animals, the process contains similarities and differences between these two types of eukaryotic cells.
Similarities
* During Prophase, chromosomes condense * In Prometaphase, the nuclear envelope breaks down, the chromosomes move towards the metaphase plate, and the spindle grabs the chromosomes * In Metaphase, the chromosomes align at the equator * In Anaphase, they move towards opposite poles * In Telophase, the nuclear envelope appears again, chromosomes de-condense, and the spindle breaks down.
Differences
* In Prophase, animal cells have centrioles that organize spindles while plant cells don't. Plants also have a pre-prophase band, which consists of actin and microtubules, that forms in the place where the cell wall will appear * During Prometaphase, the pre-prophase band of plant cells disappears. * During Telophase, animal cells have a contractile ring, which is made of actin and myosin, that forms halfway between the two nuclei in the dividing cell. In Plant cells, a phragmoplast, which is made of actin, myosin, and microtubules, forms in the center of the cell where the cell wall will appear * In Cytokinesis, the contractile ring in animal cells contracts and pinches the cell into 2 daughter cells.
In plants, the phragmoplast extends and forms the cell wall. * In plants, mitosis occurs only in the meristem tissues. They are located at the tips of roots, shoots, and in the stem, between the xylem and phloem.
Why mitosis? 1. Growth. The number of cells within an organism increases by mitosis and this is the basis of growth in multicellular organisms. 2. Cell Replacement. Cells are constantly sloughed off, dying and being replaced by new ones in the skin and digestive tract. When damaged tissues are repaired, the new cells must be exact copies of the cells being replaced so as to retain normal function of cells. 3. Regeneration. Some animals can regenerate parts of the body, and production of new cells are achieved by mitosis. 4. Asexual Reproduction. Some plants produce offspring which are genetically similar to themselves. These offspring are called clones. a) Binary Fission – Single celled organism (e.g. amoeba) reproduce simply by splitting into two new cells b) Budding – bud on parent organism (e.g. yeast) develops into new organism through repeated cell
division c) Vegetative Reproduction – Plants send out stolons (above ground) or rhizomes (underground) which become new individuals e.g. strawberries, Bermuda grass, and ferns.
What is Mitosis?
There are various structures within the cell, but many are too difficult to see. For example, within the nucleus lie the chromosomes. These are important for heredity and reproduction. When a cell splits and becomes two, certain processes occur within the nucleus first. One of these processes involves the splitting of the chromosomes. This process is called Mitosis and there are four distinct stages.
Mitosis takes place in Regular Body Cells or Somatic Cell. It keeps Cells Living and Growing.
Events during Mitosis | | Interphase: Cells may appear inactive during this stage, but they are quite the opposite. This is the longest period of the complete cell cycle during which DNA replicates, the centrioles …show more content…
divide, and proteins are actively produced. | | Prophase: During this first mitotic stage, the nucleolus fades and chromatin (replicated DNA and associated proteins) condenses into chromosomes.
Each replicated chromosome comprises two chromatids, both with the same genetic information. Microtubules of the cytoskeleton, responsible for cell shape, motility and attachment to other cells during interphase, disassemble. And the building blocks of these microtubules are used to grow the mitotic spindle from the region of the centrosomes. | | Prometaphase: In this stage the nuclear envelope breaks down so there is no longer a recognizable nucleus. Some mitotic spindle fibers elongate from the centrosomes and attach to kinetochores, protein bundles at the centromere region on the chromosomes where sister chromatids are joined. Other spindle fibers elongate but instead of attaching to chromosomes, overlap each other at the cell center. …show more content…
| | Metaphase: Tension applied by the spindle fibers aligns all chromosomes in one plane at the center of the cell. | | Anaphase: Spindle fibers shorten, the kinetochores separate, and the chromatids (daughter chromosomes) are pulled apart and begin moving to the cell poles. | | Telophase: The daughter chromosomes arrive at the poles and the spindle fibers that have pulled them apart disappear. | | Cytokinesis: The spindle fibers not attached to chromosomes begin breaking down until only that portion of overlap is left. It is in this region that a contractile ring cleaves the cell into two daughter cells. Microtubules then reorganize into a new cytoskeleton for the return to interphase. |
Mitosis Plants vs. Animals
While the main purpose of mitosis remains the same in plants and animals, the process contains similarities and differences between these two types of eukaryotic cells.
Similarities
* During Prophase, chromosomes condense * In Prometaphase, the nuclear envelope breaks down, the chromosomes move towards the metaphase plate, and the spindle grabs the chromosomes * In Metaphase, the chromosomes align at the equator * In Anaphase, they move towards opposite poles * In Telophase, the nuclear envelope appears again, chromosomes de-condense, and the spindle breaks down.
Differences
* In Prophase, animal cells have centrioles that organize spindles while plant cells don't. Plants also have a pre-prophase band, which consists of actin and microtubules, that forms in the place where the cell wall will appear * During Prometaphase, the pre-prophase band of plant cells disappears. * During Telophase, animal cells have a contractile ring, which is made of actin and myosin, that forms halfway between the two nuclei in the dividing cell. In Plant cells, a phragmoplast, which is made of actin, myosin, and microtubules, forms in the center of the cell where the cell wall will appear * In Cytokinesis, the contractile ring in animal cells contracts and pinches the cell into 2 daughter cells.
In plants, the phragmoplast extends and forms the cell wall. * In plants, mitosis occurs only in the meristem tissues. They are located at the tips of roots, shoots, and in the stem, between the xylem and phloem.
Why mitosis? 1. Growth. The number of cells within an organism increases by mitosis and this is the basis of growth in multicellular organisms. 2. Cell Replacement. Cells are constantly sloughed off, dying and being replaced by new ones in the skin and digestive tract. When damaged tissues are repaired, the new cells must be exact copies of the cells being replaced so as to retain normal function of cells. 3. Regeneration. Some animals can regenerate parts of the body, and production of new cells are achieved by mitosis. 4. Asexual Reproduction. Some plants produce offspring which are genetically similar to themselves. These offspring are called clones. a) Binary Fission – Single celled organism (e.g. amoeba) reproduce simply by splitting into two new cells b) Budding – bud on parent organism (e.g. yeast) develops into new organism through repeated cell
division c) Vegetative Reproduction – Plants send out stolons (above ground) or rhizomes (underground) which become new individuals e.g. strawberries, Bermuda grass, and ferns.