What Happens to Genetic Material During Cell Division?
The genetic material in cells is called DNA (deoxyribonucleic acid). A DNA molecule contains the information that determines the traits that a living thing inherits and needs to live. It contains instructions for an organism's growth, development, and activities. In eukaryotes, DNA is found in the nucleus.
During most of a cell's life cycle, DNA, along with proteins, is a mass of loose strands called chromatin (KROH-muh-tin). Before cell divion, DNA is duplicated, or copied. Then, in an early stage of cell division, the chromatin is compacted into visible structures called chromosomes (KROH-muh-sohmz). A duplicated chromosomes consists of two identical structures called chromatid (KROH-muh-tidz). The chromatids are held together by a centromere (SEN-truh-mir).
During most of a cell's life cycle, DNA, along with proteins, is a mass of loose strands called chromatin (KROH-muh-tin). Before cell divion, DNA is duplicated, or copied. Then, in an early stage of cell division, the chromatin is compacted into visible structures called chromosomes (KROH-muh-sohmz). A duplicated chromosomes consists of two identical structures called chromatid (KROH-muh-tidz). The chromatids are held together by a centromere (SEN-truh-mir).
Why is cell division important?
All living things are made up of cells. Many organisms start as one cell. The cell divides and becomes two cells, two cells become four, four become eight, and so on. Through the process of cell division, the organism grows. Cell division is still important after an organism stops growing. For example, every day billions of your red blood cells wear out and are replace through cell division. During the time it takes you to read this sentence, your bone marrow produced about six million red blood cells. Cell division is the way a one-celled organism, a unicellular organism, makes another organism of its kind. When a one-celled organisms reaches a certain size, it reproduces by dividing into two cells.
The Cell Cycle And Cell Cycle Stages
Every living organism has a life cycle. The life cycle of an organism includes birth, growth, reproduction, and death. The life cycle of a eukaryote cell, called the cell cycle, can be divided into three states: interphase, mitosis, and cytokinesis.
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Interphase
The part of the cell cycle during which the cell is not dividing is called interphase (IN-ter-fayz). A lot of activity takes place in this stage of the cell's life. The cell grows to about twice the size it was when it was first produced. It also produces various organelles. The cell engages in normal life activities, such as transporting materials into the cell and getting of wastes.
Changes that occur during interphase prepare a cell for division. Before a cell can divide, DNA must be duplicated. This ensures that after cell division, each new cell gets an exact copy of the genetic material in the original cell.
Changes that occur during interphase prepare a cell for division. Before a cell can divide, DNA must be duplicated. This ensures that after cell division, each new cell gets an exact copy of the genetic material in the original cell.
Mitosis
In eukaryotic cells, mitosis (my-TOH-sis) is the part of the cell cycle during which the nucleus divides. Prokaryotes do not undergo mitosis because they do not have a nucleus. Mitosis results in two nuclei that are identical to the original nucleus. So, the two new cells formed after cell division have the same genetic material. During mitosis, chromosomes condense from chromatin. When viewed with a microscope, chromosomes are visible inside the nucleus. At the end of mitosis, the cell has two identical sets of chromosomes in two separate nuclei.
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Cytokinesis
Cytokinesis (sy-toh-kuh-NEE-sis) is the division of the parent cell's cytoplasm. Cytokinesis begins during the last step of mitosis. During cytokinesis, the cell membrane pinches inward between the new nuclei. Eventually, it pinches all the way, forming two complete cells called daughter cells.
In a cell that has a cell wall, such as a plant cell, a cell plate forms. The cell plate becomes cell membranes that separate the new cells. New cell walls form where the plate was. |
What are the phases of mitosis?
Mitosis has four phases: prophase (PROH-fayz), metaphase (MET-uh-fayz), anaphase (AN-uh-fayz), and telosphase (TEE-lo-fayz). I have heard telophase pronounced tel-o-phase, too.) By the end of these phases, the cell will have two identical nuclei and cytokinesis will begin.
Prophase
During prophase, the chromatin in the nucleus of a cell condenses and becomes visible under a microscope. Each chromosome consists of two chromatids held together by a centromere. The membrane around the nucleus breaks down.
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METAPHASE
During metaphase, chromosomes line up in the middle of the cell. Centromeres of the chromosomes are the same distance from each side of the cell.
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ANAPHASE
During anaphase, the chromatids separate. They are pulled to opposite sides of the cell. Each side of the cell ends up with a complete set of chromosomes.
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Telophase
The last phase of mitosis is telophase. A new nuclear membrance forms around each group of chromosomes. So, the cell now has two identical nuclei. The chromosomes unwind into chromatin and mitosis ENDS. Cytokinesis, which is part of the cell cycle, begins during this phase.
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