Name Class Date
10.3 Regulating the Cell Cycle
Lesson Objectives
Describe how the cell cycle is regulated.
Explain how cancer cells are different from other cells.
Lesson Summary
Controls on Cell Division Dozens of proteins regulate the cell cycle.
Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells.
Regulatory proteins work both inside and outside of the cell.
Internal regulators allow the cell cycle to proceed when certain events have occurred
within a cell.
External regulators called growth factors stimulate the cell cycle. Other external
regulators cause the cell cycle to slow down or stop.
Apoptosis is programmed cell death that plays a key role in the development of tissues
and organs.
Cancer: Uncontrolled Cell Growth Cancer is a disorder in which cells divide
uncontrollably, forming a mass of cells called a tumor.
Cancers are caused by defects in genes that regulate cell growth.
Treatments for cancer include:
removal of cancerous tumors.
radiation, which interferes with the copying of DNA in multiplying cancer cells.
chemotherapy, which is the use of chemicals to kill cancer cells.
Controls on Cell Division
For Questions 1–6, write True if the statement is true. If the statement is false,
change the underlined word or words to make the statement true.
1. Cells tend to continue dividing when they come into contact with other
cells.
2. Cell division speeds up when the healing process nears completion.
3. Proteins called growth factors regulate the timing of the cell cycle in
eukaryotic cells.
4. If chromosomes have not attached to spindle fibers during metaphase,
an internal regulatory protein will prevent the cell from entering
anaphase.
5. Growth factors are external regulatory proteins that slow down the cell
cycle.
6. Once apoptosis is triggered, a cell proceeds to self-destruct.
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