Upload
ira-mccoy
View
212
Download
0
Embed Size (px)
Citation preview
CONTROL OF CELL DIVISION:MITOSIS GONE WRONGMrs. Stewart
Central Magnet School
Honors Biology
WHAT TRIGGERS A CELL TO BEGIN MITOSIS?
Proteins regulate the progress of cell division A system of checkpoints occurs
Certain feedback signals from the cell can trigger the proteins to initiate the next phase of the cell cycle
3 CHECKPOINTS FOR MITOSIS
G1 – cell growth checkpoint G2 – DNA synthesis checkpoint Mitosis checkpoint
G1 – CELL GROWTH CHECKPOINT
If the cell is healthy and the cell has grown to a suitable size proteins initiate S phase (DNA replication)
If DNA replication is not favorable in the cell’s current condition/environment, cell cycle stops here (G0)
Or if cell needs rest (G0)** Cells that enter G0 will likely never divide again
G2 – DNA SYNTHESIS CHECKPOINT
After DNA has replicated itself DNA repair enzymes are triggered to check
the results of DNA replication for errors If this checkpoint is passed, proteins signal
the cell to begin mitosis
MITOSIS CHECKPOINT
If a cell passes this checkpoint, proteins signal the cell to exit mitosis and enter G1 phases once again
THINK – PAIR – SHARE
What could be a complication of cells dividing too many times / too rapidly?
WHEN CONTROL IS LOST:
The proteins that control the process of cell division are coded for by genes
If there is a mutation, those proteins are created incorrectly
If a protein is shaped wrong, it cannot function correctly
uncontrolled cell growth
CANCER
Tumors - a collection of cells dividing out of control
They require more resources than surrounding cells because they are more active
Starve all surrounding cells Can break off and travel through bloodstream to
spread