Cell Cycle Regulation
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What are the three main checkpoints in the cell cycle?
G1, G2, M
What are two types of regulatory proteins found in the cell cycle?
• Cyclins 2. Cyclin-Dependent Kinases (Cdks)
Activity of Cdk rising and falling is dependent on what?
Concentration of cyclin
What is the role of Cdks?
Phosphorylation
What is the role of MPF?
Triggers cell past G2 checkpoint and into the M phase
What is the role of the G1 checkpoint?
Push the cell through rest of cell cycle, check for growth, and DNA damage
Where is a cell sent if it is not ready for cell division?
G0 phase (most cells in the body are at this stage)
What is the role of the G2 checkpoint?
Checks to make sure that the cell is ready for division and that there are no errors in the DNA replication
What is the role of the M chekcpoint?
Make sure all the chromosomes are attached to the kinetochore microtubules
What are growth factors?
Released by certain cells and stimulate other cells to divide (ex. Platelet-derived growth factor)
What are two effects fo external signals at the checkpoints?
• Anchorage dependence (cells require a surface for division) • Density-dependence inhibition (crowded cells stop dividing and form a single layer)
What is lost in cancer cells?
Control of the cell cycle
What are some effects of the loss of control of the cell cycle in cancer cells? (2)
• Do not respond normally to body’s control mechanisms • Do not need growth factors to grow and divide: a. They make their own growth factor b. They may convey a growth factor’s signal without the presence of growth factor c. They may have abnormal cell cycle control system
What is transformation?
Process where cells that acquire the ability to divide indefinitely
What system in the body will try to eliminate cancer cells?
Immune system
What are the two types of tumors? Define each
• Benign- abnormal cells remain only at original site 2. Malignant- invade surrounding tissues and can undergo metastasis
What is metastasis?
Spread of cancer cells to other parts of the body
How does a localized tumor be treated?
Radiation
How does a metastatic tumor be treated?
Chemotherapy
What can cause cancer?
Mutations to genes that normally regulate cell growth and division
What kind of mutations can occur? (2)
• Spontaneous mutations 2. Environmental influences such as mutagens and some viruses
What are oncogenes?
Cancer-causing genes
What are proto-oncogenes?
Corresponding normal cellular genes responsible for normal cell growth/division, usually genes that promote cell division
Cancer caused by viruses make up ______% of all human cancers
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