cell cycle, mitosis, and meiosis
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Cell Cycle, Mitosis, and Meiosis. Why do cells divide?. Most cells go through a series of changes in order to maintain homeostasis. Cells need to reproduce ( divide ) when their surface area can no longer supply the much larger volume with nutrients and get rid of wastes. Cell Division. - PowerPoint PPT PresentationTRANSCRIPT
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Cell Cycle, Mitosis, and Meiosis
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Why do cells divide?Most cells go through a series of changes in order
to maintain homeostasis.Cells need to reproduce (divide) when their surface area
can no longer supply the much larger volume with nutrients and get rid of wastes.
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Cell Division•The process by which a cell divides into
two new daughter cells
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Chromosomes•Made of DNA (carries the cell’s genetic
information) and proteins▫Every organism has a specific number of
chromosomes Humans have 46
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Chromosomes•Only visible during cell division•Each chromosome is copied before cell division
▫Each chromosome is made of two identical “sister” chromatids Each pair of chromatids is attached by a centromere
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The Cell Cycle•The series of events that cells go through
as they grow and divide
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The Cell Cycle•Interphase – the period of growth in
between cell divisions•Three phases of interphase
▫G1
▫S▫G2
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Interphase – G1 phase•Phase where cells do the most growing•Cells increase in size and make new
proteins and organelles
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Interphase – S phase•Chromosomes are replicated (copied)•Synthesis (making) of DNA molecules occurs
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Interphase – G2•Organelles and other molecules required for
cell division are produced.•Once completed, the cell will enter mitosis
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Mitosis•The division of the cell nucleus•Divided into four phases (PMAT):
▫Prophase▫Metaphase▫Anaphase▫Telophase
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Prophase•Chromosomes become visible•Nuclear envelope breaks down•Centrioles separate•Spindles form
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Metaphase•Chromosomes line up along the center of the cell
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Anaphase•Sister chromatids separate•Individual chromosomes are moved apart
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Telophase•Chromosomes gather at opposite ends of the cell•Two new nuclear envelopes form
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Cytokinesis•The cytoplasm pinches in two – two new
daughter cells are formed•In plants a cell plate divides the
cytoplasm before the cell wall forms
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Cancer Cells 1. Normal cells contain check points to regulate
the cell cycle, & stop at appropriate check points.2. Cancerous cells do not respond to check points
and continue rapidly through the cell cycle. This results in masses of undefined cells called tumors.
3. Cancer cells do not mature; they become more immature.
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Binary Fission•The asexual reproduction of a bacterial cell