Section 5-3

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Section 5-3 5-5Cancer Stem Cells

• Write everything that is underlined

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5.3 KEY CONCEPTCell cycle regulation is
necessary for healthy growth
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I. Cell Division1. Internal and external factors
regulate (control) cell division

• a. External factors include physical and chemical
  signals
• b. Growth factors are proteins that stimulate
  cell division
• Most mammal cells form a single layer in a
  culture dish and stop dividing once they touch
  other cells

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2. Apoptosis is programmed cell death

• a normal feature of healthy organisms
• caused by a cells production of self-destructive
  enzymes
• occurs indevelopmentof infants

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II. Cancer Cells 1. Cell division is
uncontrolled in cancer

• 2. Cancer cells form disorganized clumps called
  tumors

• Benign (good) tumors remain clustered and can be
  removed
• Malignant (bad) tumors metastasize, or break
  away, and can form more tumors

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normal cell
cancer cell
bloodstream
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• 3. Cancer cells do not carry out their necessary
  functions

4. Cancer cells come from normal cells with
damage to genes involved in cell-cycle regulation
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• 5. Carcinogens are substances known to cause
  cancer

6. Standard cancer treatments typically kill both
cancerous and healthy cells
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5.5 KEY CONCEPT Cells work together to carry out
complex functions
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I. Specialized Cells1. Specialized cells perform
specific functions.

• Cells develop into their mature forms through the
  process of cell differentiation
• 2. Cells are different because different
  combinations of genes are expressed
• A cells location in an embryo helps determine
  how it will differentiate

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II. Stem Cells1. Stem cells are unique body
cells.

• 2. Stem cells have the ability to
• divide and renew themselves
• remain undifferentiated in form
• develop into a variety of specialized cell types

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• Stem cells come from adults and embryos

• Adult stem cells can be hard to isolate and grow.
• The use of adult stem cells may prevent
  transplant rejection.
• The use of embryonicstem cells raisesethical
  issues
• Embryonic stem cellscan be grown indefinitelyin
  culture.