KEY CONCEPT Cells divide during mitosis and cytokinesis.
One half of a duplicated chromosome is a chromatid. One long continuous thread of DNA coiled around histones (proteins) is called chromatin. chromatid centromere telomere Condensed, duplicated chromosome One half of a duplicated chromosome is a chromatid. Sister chromatids are held together at the centromere. Telomeres protect DNA and do not include genes.
Chromosomes condense at the start of mitosis. DNA wraps around proteins (histones) that condense it. DNA double helix DNA and histones Chromatin Supercoiled DNA
1.Interphase prepares the cell to divide. B. Mitotic Phase- Mitosis and cytokinesis produce two genetically identical daughter cells. Parent cell centrioles spindle fibers centrosome nucleus with DNA 1.Interphase prepares the cell to divide. DNA is duplicated.
Cell structures and mitosis Centrosomes-organelle that is the main microtubule organizing center. Aster-cellular star shaped structure that forms around the centrosome-made of microtubules Equator-mid section of the dividing cell Cleavage furrow - indentation that begins the formation of the new cell membrane Cell plate- the new cell wall Kinetorchore fibers- attachment points on the centromere where the chromosomes are held together to make an X Spindle- fibers that separate the chromosomes Microtubules-hollow, protein fibers and rods. Cytokinesis-division of the cytoplasm results two daughter cells.
2.During prophase, chromosomes condense, nuclear membrane, nucleus, and nucleolus disappear, spindle fibers form, centrioles make spindle fibers
3.During metaphase- spindle fibers randomly align sister chromatids in the middle of the cell (equator)
4.During anaphase- spindle fibers retract and pull the sister chromatids opposite sides of the cell (poles)
5.During telophase- chromosomes uncoil, nuclear membrane reforms, nucleolus reforms.
6.Cytokinesis-division of the cytoplasm In animal cells, the membrane pinches closed at a point called cleavage furrow. In plant cells-vacuoles join together and form a cell plate. Result-2 identical daughter cells with identical copies of genetic material-DNA