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Mrs. Gilbert Identify the phases of the cell cycle Discuss the activities of each phase of mitosis Compare the genetic makeup of cells before and after mitosis Compare reproduction in eukaryotic and prokaryotic cells Cell cycle Centromere Cleavage furrow Cytokinesis Deoxyribonucleic acid (DNA) Interphase Metaphase Mitosis Sister chromatid Spindle fibers Defined- a course or series of events or operations that repeats One pattern seen in different parts of life Saying life runs in cycles means that many of life’s activities repeat themselves. It also means that many actions start at one point. These actions go through different steps to return to that same point. Upon returning to that point, they then begin the cycle all over again. All cells are produced from other cells. But how? 3 Stages: (1) Interphase (3) Cytokinesis (2) Mitosis During interphase: the cell grows makes a copy of its DNA (DNA Replication) Deoxyribonucleic The code that controls all of the cell’s activities DNA Acid Structure = “double helix” Handrails (outside)= structural support Bases (inside) = genetic code DNA is stored in the nucleus as chromosomes DNA Replication: DNA unzips and the 2 sides separate New bases attach to the 2 old strands, creating 2 identical copies of the original DNA A cell spends most of its life in interphase Nuclear membrane & nucleolus are clearly visible Chromosomes are NOT visible During mitosis: the cell’s nucleus divides into 2 since 2 copies of DNA were made during interphase, each nucleus gets 1 complete copy Steps of Mitosis 1. Prophase Chromosomes become visible Nucleolus & nuclear membrane break down & disappear Steps of Mitosis 1. Prophase Centrioles move to opposite ends of the cell (poles) Spindle fibers appear Steps of Mitosis 2. Metaphase Chromosomes line up Centromeres attach to spindle fibers Steps of Mitosis 3. Anaphase Centromeres split 2 strands of chromosomes separate & move to opposite ends of the cell Steps of Mitosis 4. Telophase Centrioles & spindle fibers disappear Chromosomes become harder to see Steps of Mitosis 4. Telophase Nuclear membrane & nucleolus reform Plant Cell Mitosis Animal Cell Mitosis During cytokinesis: The cell’s cytoplasm divides to create 2 new, identical cells 2 copies of DNA are made (1) Interphase (2) Mitosis nucleus divides in 2 cytoplasm divides to create 2 identical cells (3) Cytokinesis Some organisms reproduce by mitosis Asexual reproduction: A new organism is produced from a single parent offspring are genetically identical to the parent 3 types: binary fission budding regeneration Budding—a new organism grows from the body of the parent organism Example: hydra Regeneration—a new organism can develop from a piece of the old organism Example: starfish www.sciencespot.net Biology: Cycles of life. Circle Pines: MN. AGS Publishing. (pp.3, 246-250)