Regulation of Cell Cycle

Controls of Cell Division When cells are placed in a Petri dish with nutrient broth, they will grow until they form a thin layer covering the bottom. Growth stops when cells touch each other. If cell are removed from the center, cells grow to replace them.

Injury If you cut skin or break bone, cells at the edge of the injury divide rapidly. Healing: produce new cells When healing is complete, rate of cell division slows and returns to normal.

Cell Cycle Regulator Cyclin – protein regulating the timing of the cell cycle in eukaryotic cells. Internal Regulators respond to events inside the cell cells don’t enter mitosis until all chromosomes have been replicated External Regulators speed up or slow down the cell cycle Growth Factors: embryonic development & wound healing

Uncontrolled Cell Growth Cancer – cells do not respond to the signals that regulate growth Result: divide uncontrollably Form tumors, masses of cells Tumors break loose and spread throughout the body Causes: radiation exposure, viral infections, genetics Defect in gene p53: regulates cell growth

Brain Tumor