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Cell Cycle Notes. 4 Reasons why cells divide. Efficiency DNA Overload Growth Replace Cells. http://www.animationlibrary.com. Cell Division in Prokaryotes. Called Binary Fission DNA is copied & cell divides. Cell Division in Eukaryotes. Called Mitosis
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4 Reasons why cells divide • Efficiency • DNA Overload • Growth • Replace Cells http://www.animationlibrary.com
Cell Division in Prokaryotes • Called Binary Fission • DNA is copied & cell divides
Cell Division in Eukaryotes • Called Mitosis • Cell Grows & Copies its DNA then divides
The series of events that cells go through as they grow & divide ~ The Cell Cycle
2 Phases of the Cell Cycle • Interphase • “M” Phase • Includes Mitosis & Cytokinesis
Interphase: a growth period • G1 (Growth/Gap 1) - Cell grows in size, makes new organelles & performs assigned function; DNA is relaxed in chromatin and is not visible • S phase (Synthesis) - duplicates DNA to prepare for mitosis • G2 (Growth/Gap 2) – cell prepares for mitosis
Vocab Terms • Chromatin DNA “scrunched up” in the nucleus & is not visible
Vocab Terms • Chromatin DNA “scrunched up” in the nucleus & is not visible • Chromosomecell structure that carries the genetic material; visible during mitosis
Vocab Terms • Sister chromatidsidentical halves of the duplicated parent chromosome • Centromerecell structure that joins the two sister chromatids of a chromosome
Prophase • DNA organizes • chromatin condense into visible chromosomes (of two sister chromatids held together as a pair by a centromere. • Nuclear membrane & nucleolus disappear. • Spindle fibers form between the pairs of centrioles
Metaphase • Chromosomes line up in the middle of the cell. • Each chromatid is attached to a separate spindle fiber by its centromere.
Anaphase • Sister chromatids are pulled apart to opposite poles of the cell.
Telophase • 2 identical daughter cells are formed. • Cytokinesis occurs (the division of the cytoplasm) as the plasma membrane pinches in along the equator. • Nucleolus and nuclear membrane reappear, chromosomes begin to uncoil & relax back into chromatin
Microscope video of the cell cycleMicroscope video of the cell cycle 2Embryonic development video
Picture of cytokinesis *Image courtesy Indigo Instruments. Visit indigo.com for more original content like this. Reprint permission is granted with this footer included.*
Plants in cytokinesis • Because plant cells have a cell wall, a cell plate forms across the cell’s equator instead of pinching in.
Finally… • After mitosis is complete, each new daughter cell is an identical copy of the parent cell.
Cell Cycle Pneumonic • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis • I • Put • My • Apples • To • Cook
Cell Cycle Video Lingering Questions…. • How long does the cell spend in each phase? • What is the life span of human cells? • What happens when the cell is NOT growing or dividing? • Does the cell continue in the cell cycle indefinitely?
Think-Pair-Share:Explain why damage to heart muscle cells are permanent Explain why spinal cord injuries are irreversible
What happens when the cell is not growing or dividing? Cell is resting
When cells are damaged and need repair or need to be replaced, cell will re-enter the cell cycle
Talk to a Partner: Do Cells Grow Indefinitely? Section 10-3 If center cells are removed, cells near the space will start to grow again until they touch or can’t absorb nutrients. SHOWS: Cell division genes can be turned on and off Cells grow until they touch other cells
Cancer • Some cells do not respond to the signals that regulate the growth (skip G0) • Result ~ uncontrolled cell growth: cancer • Causes of cancer: • cigarette & tobacco use • radiation exposure (X-ray & UV light) • genetics • some viruses
Stem Cells • Stem cells - unspecialized cells • Through cell differentiation – stem cells become specialized in structure and function • Two Types: Embryonic and Adult Stem Cells