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Transcript
Cell Division 10-2 Cell Division In Section 10-2 we will talk about cell division of both prokaryotic and eukaryotic cells Even though prokaryotic cells do not have a nucleus they can still go through cell division They simply make a copy of the genetic material and split the total contents of the cell in two Eukaryotes have a much more complex Chromosomes In Eukaryotic cells, the genetic information that is passed on is contained in chromosomes Chromosomes are made up of DNA and proteins, as you should recall Chromosomes Chromosomes are not visible in most cells except during cell division Well before cell division, chromosomes must replicate This makes pairs of “sister chromatids” Chromosomes Each pair of “sister chromatids” is bound together near the center by a centromere In a human cell there are 46 chromosomes, each of which consist of a pair of chromatids The Cell Cycle The life cycle of a cell is known as the cell cycle This cycle represents what happens to a cell during cell division and between cell divisions The Cell Cycle The “in between” phases are grouped together to be called interphase Interphase consists of three individual phases G1 Phase, S Phase, G2 Phase G1 Phase The G1 phase is a period of cell growth During this phase the cell will get slightly larger and more mature S Phase The S Phase is the period of DNA replication During this phase DNA is replicated so that when division occurs, there is a complete set of DNA for each daughter cell G2 Phase The G2 Phase is a preparation for Mitosis During this phase many of the organelles needed to assist in replication are produced Mitosis Mitosis Biologists divide the events of mitosis into four phases Prophase Metaphase Anaphase Telophase Prophase Prophase is the first and longest phase of mitosis It takes up approximately 4060% of the total time of mitosis Prophase During prophase chromatin condenses into chromosomes Centrioles, two tiny structures located in the cytoplasm near the nuclear envelope, separate and take up positions on Prophase The spindle, a fanlike microtubule that helps separate the chromosomes later, forms during prophase as well The spindle will become attached to centromeres by fibers Prophase The last thing to occur in prophase is the breaking down of the nuclear membrane Metaphase Metaphase is the second phase of mitosis The chromosomes line up across the center of the cell during metaphase Anaphase Anaphase is the third phase of mitosis The sister chromatids separate into individual chromosomes and are pulled apart Telophase Telophase is the fourth and final phase of mitosis The chromosomes will gather at opposite ends of the cell and start to unwind back into chromatin The two new nuclear envelops Cytokinesis There is one step that must occur after mitosis for division to be complete Cytokinesis is the splitting of the cytoplasm into two equal halves This creates the