Cell Cycle Cell Division
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? - Somatic Cells 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 – 3 Parts Interphase – cell growth takes place Inter = enter Mitosis – division of DNA(chromosomes) mito = strong, powerful sis = 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
What is the 2nd part of the cell cycle? Mitosis Prophase Metaphase Anaphase Telophase
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? Gain-of-function mutations (oncogenes) Loss of function mutations (“tumor suppressor” genes) proteins involved in regulating cell division events no longer appropriately drive progression from one cell cycle stage to the next Example: Cancer is uncontrolled cell division or inappropriate cell proliferation
Independent Activity In ten minutes, you will be able to write 6 sentences using the following words: Interphase Prophase Metaphase Anaphase Telophase Cytokinesis