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CELL CYCLECell Division
cancer
https://science.education.nih.gov/supplements/nih1/cancer/activities/activity2_animations.htm
Strawberry Division!
Why do cells need to divide? Growth – so organisms can increase in
size (natural selection theory) Development – for cells to become
specialized (e.g. create organs) Repair – for cells to replace removed or
dead cells (e.g skin cells)
Which cells divide the most? Skin cells are dividing all day, everyday. We lose around 30,000 to 40,000 skin cells a
minute! That’s 50 million skin cells lost in one day!
Cell Cycle – Somatic Cells
Interphase – cell growth takes placeInter = enter
Mitosis – division of DNA(chromosomes)mito = strong, powerfulsis = process
Cytokinesis – division of cytoplasm cyto = cell
kinesis = movement
What is the 1st part of the cell cycle?
Interphase G1 (growth stage one) : cell is
growing & developing and making proteins
S (synthesis): DNA replication process
G2 (growth stage two): cell is making final preparations for cell division
Cell Cycle
Closer look at “S phase”
What is the 2nd part of the cell cycle?
MitosisProphaseMetaphaseAnaphaseTelophase/Cytokinesis
Mitosis
Prophase-chromatin begins to coil into think, visible chromosomes
Mitosis
Metaphase-spindles fibers line up chromosomes in the “middle”
Mitosis
Anaphase-spindle fibers move chromosomes “apart”
Mitosis
Telophase-chromosomes reach opposite ends-centromere
Cytokinesis
Animal Cell Plant Cell
Cytokinesis: Which cell is pictured?
What happens if the cycle is disrupted?
Cancer is uncontrolled cell division or inappropriate cell proliferation
Cascade of chemical reactions that relay a cell from one stage to the next
Set of checkpoints that monitor completion of critical events and delay progression to thenext stage, if necessary
Genetic alterations shown to contribute to cancer development
Gain-of-function mutations (oncogenes) Loss of function mutations (“tumor suppressor” genes)
Independent Activity
In ten minutes, you will be able to write 6 sentences using the following words:
Interphase Prophase Metaphase Anaphase Telophase Cytokinesis