CellDivision.pptx

Cell Cycle  The cyclical process of growth and mitosis.  It consists of interphase and mitosis. CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 1 1  INTERPHASE  It is the stage...

Cell Cycle  The cyclical process of growth and mitosis.  It consists of interphase and mitosis. CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 1 1  INTERPHASE  It is the stage between cell division.  It occupies about 90% of the total cell cycle.  It is the period during which the normal activities of the cell take place.  The nucleus is clearly visible with one or more distinct nucleoli.  The chromosomes appear as irregular - granular form. http://www.phschool.com/science/biology_place/labbench/lab3/interphs.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 2 2  INTERPHASE  It is divided into: 1. G1 period  Represents the early growth phase of the cell.  The cell grows in volume as it produces tRNA, mRNA, ribosomes, enzymes, and other cell components. 2. S period  Growth continues, but this phase also involves DNA replication. 3. G2 period  Prepares the cell for division.  It includes replication of the mitochondria and other organelles.  Synthesis of microtubules and protein that will make up the mitotic spindle fibers.  Chromosome condensation CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 3 3  Mitosis Produces two daughter cells with the same quantity and quality of chromosomes as the parent cell Also called duplication division Refers to the division of the nucleus (karyokinesis). Quickly followed by the division of the cytoplasm (cytokinesis) Consists of four phases: Prophase Metaphase Anaphase telophase CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 4 4  PROPHASE  The chromatin condenses into chromosomes.  Each chromosomes consists of two chromatids joined at the centromere.  The centrioles move to the opposite ends of the cell.  The nucleolus and the nuclear envelope disappear.  Mitotic apparatus are nearly formed. (asters and spindle fibers in animal cell) http://www.phschool.com/science/biology_place/labbench/lab3/prophase.htm l CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 5 5  METAPHASE  Mitotic spindle is now fully formed.  The chromosomes align in the center of the cell in association with the spindle fibers. http://www.phschool.com/science/biology_place/labbench/lab3/metaphase.ht ml CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 6 6  ANAPHASE  The phase of migration.  The chromatids separate to form two sets of identical chromosomes.  The chromosomes assisted by the spindle fibers, move toward the centrioles at each end of the cell.  Cytokinesis begins: plant – cell plate formation, animals – formation of cleavage furrow. http://www.phschool.com/science/biology_place/labbench/lab3/anaphase.ht ml CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 7 7  TELOPHASE  The phase of reconstruction.  It begins when the two groups of chromosomes have reached opposite ends of the cell.  Chromosomes uncoil.  Centrioles are replicated.  Nucleolus re appears.  Nuclear membranes form.  Spindle disappears.  Cytokinesis completed resulting into two daughter cells with the same quantity and quality of chromosomes as the parent cell. http://www.phschool.com/science/biology_place/labbench/lab3/telophas.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 8 8  CYTOKINESIS Source: General Biology 1 (Revised Edition), 2017, Jo-es Publishing CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 9 9  Meiosis Produces four daughter cell with haploid number of chromosomes as the parent cell Also called reduction division Involves two successive divisions – meiosis I and meiosis II Meiosis I Results in reducing the number of chromosomes Accompanied by cytokinesis CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 10 10  PROPHASE I  It occupies the longest duration of meiosis.  As the chromosomes coil up, special proteins cause the homologous chromosomes to stick together in pairs.  The resulting structure has four chromatids.  Within each set, chromatids of the homologous chromosomes exchange corresponding segments - they “cross over”.  As prophase I continues: - the chromosomes coil up further, - spindle forms, and - homologous pairs are moved toward the center of the cell. http://www.phschool.com/science/biology_place/biocoach/meiosis/proi.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 11 11  METAPHASE I  The homologous pairs are aligned in the middle of the cell.  The sister chromatids of each chromosome are still attached at their centromeres, where they are anchored to spindle microtubules http://www.phschool.com/science/biology_place/biocoach/meiosis/metai.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 12 12  ANAPHASE I  The attachment between the homologous chromosomes of each pair breaks.  The chromosomes now migrate toward the poles of the cell.  The sister chromatids migrate as a pair instead of splitting up.  The sister chromatids are separated not from each other but from their homologous partners. http://www.phschool.com/science/biology_place/biocoach/meiosis/anai.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 13 13  TELOPHASE I  The chromosomes arrive at the poles of the cell.  Each pole has a haploid chromosome set.  Each chromosome is still in duplicate form.  New nuclear membranes may form.  New nucleolus may form.  Cytokinesis occurs, with two haploid daughter cells are formed. http://www.phschool.com/science/biology_place/biocoach/meiosis/teloi.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 14 14  Meiosis Meiosis II  Similar to the events of mitosis  Follows interkinesis  No chromosomes replication between meiosis I and meiosis II INTERKINESIS or INTERPHASE II  A period of rest that cells enter during meiosis.  No DNA replication occurs during this stage of meiosis. CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 15 15  PROPHASE II  A spindle forms and moves the chromosomes toward the middle of the cell. http://www.phschool.com/science/biology_place/biocoach/meiosis/proii.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 16 16  METAPHASE II  The chromosomes align along the center of the cell. http://www.phschool.com/science/biology_place/biocoach/meiosis/metaii.htm l CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 17 17  ANAPHASE II  The centromeres of sister chromatids separate.  The sister chromatids of each pair move toward opposite poles of the cell. http://www.phschool.com/science/biology_place/biocoach/meiosis/anaii.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 18 18  TELOPHASE II  Nuclei forms at the cell poles.  Cytokinesis occurs at the same time.  The results will be four haploid daughter cell, each with single chromosomes. http://www.phschool.com/science/biology_place/biocoach/meiosis/teloii.html CENTRO CENTRO ESCOLAR UNIVERSITY ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 19 19 Rosario C. Salazar CENTRO ESCOLAR UNIVERSITY 20 CENTRO ESCOLAR UNIVERSITY FOR INTERNAL CIRCULATION 2019 20