AP Biology: The Cell Cycle and Mitosis Latest Update Already Passed

AP Biology: The Cell Cycle and Mitosis Latest Update Already Passed Sister Chromatids Consists of two duplicated chromosomes held together at the centromeres. Where does mitosis occur? in eukaryotes What does mitosis produce? It produces cells with nearly identical genetic makeup. Purposes of Mitosis 1. It is used for the purpose of organismal reproduction in single-celled organisms. 2. It is used for the purposes of development and cell replacement in the normal growth and maintenance of the bodies of multicellular organisms. Prokaryotes generally reproduce by a process called ____. binary fission What are the two main phases of the cell cycle? interphase and cell division Where do cells spend most of their time? interphase Phases of Interphase G1 phase, S phase, G2 phase, and G0 phase. G1 Phase The new cell grows to mature size and may begin to carry out its specific function. S Phase If the cell is going to divide again, it duplicates its chromosomes during this phase by the process of DNA replication. G2 Phase Once the DNA is replicated, the cell enters this phase during which is prepares for cell division. G0 Phase Some cells do not divide, or they delay division; these cells enter this phase sometime during G1. What is the second main phase of the cell cycle? Cell division, which includes mitosis and cytokinesis. What is mitosis? It is the division of the nucleus, which leads to the separation of the chromosomes to produce two chromatids that are attached at their centromeres. Prophase of Mitosis 1. The chromatids condense. 2. The nuclear membrane breaks down and disappears. 3. A cytoskeletal structure called the *mitotic spindle* forms, and is used to pull the chromatids apart to either pole of the cell. - Two centromeres are synthesized. - In animal cells, the centrosomes contain small cylindrical bodies called *centrioles*. - The centrosomes move to opposite sides of the cell. - Spindle fibers, made up of microtubules, radiate outward from the centrosomes and some, called *kinetochore fibers*, attach to each chromosome at its centromere. Metaphase of Mitosis The chromatids line up across the center of the cell called the *metaphase plate*. Anaphase of Mitosis 1. Chromatids separate from one another during anaphase, at which point each chromatid is now considered to be an individual chromosome. - The centromeres of the chromatids split. - The kinetochore fibers pull one copy of each chromosome to one pole and the rest to the other side of the cell. Telophase of Mitosis 1. The last stage of mitosis. - The mitotic spindle disassembles. - The chromosomes unwind from the highly compacted state. - A new nuclear membrane forms and surrounds each new complete set of chromosomes. What is cytokinesis? It is the division of the cytoplasm following mitosis whereby the two newly formed nuclei become incorporated into separate cells. Cytokinesis in Animal Cells A special collect of microfilaments of the cytoskeleton form a *cleavage furrow* in the center of the cell, which causes the cell to be pinched into two cells. Cytokinesis in Plant Cells Vesicles from the Golgi apparatus form a *cell plate* in the center of the cell along which new cell wall material is deposited between the two newly forming plasma membrane. Why is the cell cycle regulated? In order to help prevent the production of abnormal cells that could eventually become cancerous. What are the ways that the cell cycle is regulated? Checkpoints, G0 Phase, Growth Factor, Density-dependent Inhibition, and Anchorage Dependence. Checkpoints Essential *points* during the cell cycle that regulate the process of passing from one stage to the next. G0 Phase A non-dividing stage of the cell cycle that halts the cycle from proceeding. Growth Factor Protein/hormone that promotes the division of cells. Density-dependent Inhibition Process in which cells stop dividing when they are in contact with each other. Anchorage Dependence Cells must be attached to something in order to divide properly. When does regulation of the cell cycle not work? Cancer Cell, Tumor, Benign Tumor, Malignant Tumor, and Metastasis. Cancer Cell Cells that are said to be "transformed" from normal cells to cancer cells and do not exhibit density-dependent inhibition. Have uncontrolled growth pattern. Tumor A pocket of abnormal cells among normal cells. Benign Tumor Non-spreading of abnormal cells. Malignant Tumor Abnormal cells that invade and impact the normal function of an organ. Metastasis Spreading of malignant tumor to other parts of the body.