Regulating the Cell Cycle
Some cells divide every few hours (skin and digestive tract cells)
Some cells never divide (muscle and nerve cells)
How do cells know when to divide?
Internal Vs. External Regulators
Internal Regulators- responds to events occurring inside the cell (have chromosomes duplicated yet?)
External Regulators- responds to events outside the cell; should a division increase or decrease?
Apoptosis
Cells can die two ways- on accident, or on purpose (“apoptosis”)
Important during tissue development
Cancer
When the cell cycle is unregulated
Tumor: a mass of cells that divide uncontrollably
Malignant tumor: when tumor cells enter and destroy surrounding healthy tissue
Benign tumor: tumor cells do not destroy surrounding healthy cells
Cancer in the US
• 2nd leading cause of death in adults, second to heart disease
• 2nd leading cause of death in children, second to accidents
Let’s look at some cancer statistics. Count off in 6’s
Causes
• Defects in genes• Chewing/smoking
tobacco• Radiation exposure• Viral infections• UV exposure
Types of Cancers
What are the most common types of Cancers?
Men• Lung Cancer• Colorectal Cancer• Prostate Cancer
Women• Lung Cancer• Breast Cancer • Colorectal Cancer
Children and Young Adults•Leukemia•Brain and Central Nervous system tumors•Melanoma•Bone Cancer
Treatments
• Surgery• Radiation (target and
destroy cancer cells)• Chemotherapy (can
interfere with other quickly dividing cells)
• Don’t use tobacco in any form• Maintain a healthy lifestyle• Use sunscreen (UVA/UVB broad spectrum) when
outdoors• Understand your risks and get screened
Cell Differentiation
What are different types of cells we have in our bodies?
Differentiation
“The process in which a cell becomes specialized”
Occurs during the develop of the organism (the cells of an embryo have the ability to become every different cell in the body)
Stem Cells
Embryonic• Found in embryos• Can become almost all the
cells in the body
Adult• Found in adults• Used to renew and replace
cells• Can become many different
cells in the body (much more limited than embryonic)
Stem Cell Research
• Stem cells can be collected from amniotic fluid, embryos, and adults
• Helps with understanding cell differentiation
• Test new drugs • Grow tissues and organs to
replace old and failing ones to treat spinal cord injury, stroke, burns, heart disease, diabetes, and arthritis
Embryonic Stem Cells
• Collected from in vitro fertilized embryos donated for research
• Can easily be grown in laboratory cultures
Adult Stem Cells
• Collected from adult tissues
• Very few in the body, and collecting them lessens their ability to divide
• More difficult to grow in labs
• Used for bone marrow transplants
Controversy
• There are controversies regarding the ethics of using a human embryo to acquire stem cells
• Retrieving the stem cells destroys the embryo
• When does life begin?
What are some arguments?
Pro Stem Cell Research Against Stem Cell Research
What do you want to learn more about?
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