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Cell Division Mitosis and Cytokinesis Cell Reproduction • Interphase – Cell growth, DNA synthesis, Growth and Preparation • Mitosis (Division) – dividing the nucleus into two daughter nuclei • Cytokinesis (Division) – separating the organelles and the cytoplasm Mitosis • Mitosis is a continuous process that can be observed in four stages: – Prophase – Metaphase – Anaphase – Telophase Prophase 1 • Chromosomes begin to condense • The nuclear membrane breaks down. • Spindle which is made up of several spindle fibers form. – run at a right angle to the cell’s equator. • An organelle called the centrosome helps assemble the spindle. – animal cells includes a pair of centrioles – centrosomes move to opposite poles of the cell Metaphase • Chromosomes are packaged into their most condensed form. • Nuclear membrane is fully dissolved • Chromosomes move to the center of the cell • Spindle fibers form a link between the poles and the centromere of each chromosome. Anaphase • Spindle fibers shorten • Sister chromatids move toward opposite poles as the spindle fibers shorten. • Each pole now has a full set of chromosomes. Telophase • A nuclear envelope forms around the chromosomes at each pole of the cell. • Chromosomes now uncoil. • The spindle dissolves. • Mitosis is complete. Cytokinesis • The cytoplasm is separated • Two daughter cells are formed – Have half of the parent’s cytoplasm and organelles – Genetically identical diploid cells • After cytokinesis, each cell enters the G1 stage of interphase. • Summary The life of a eukaryotic cell cycles through; – Growth, DNA replication – preparation for cell division – division of the nucleus and cytoplasm • Mitosis is a continuous process that includes four stages: – – – – Prophase Metaphase Anaphase Telophase • Cytokinesis – the cell membrane grows into the center of the cell and divides it into two daughter cells – each daughter cell has about half of the parent’s cytoplasm and organelles