LEQ: How do cells become committed to specialized functions in bodies?

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LEQ How do cells become committed to specialized
functions in bodies?

• Key terms stem cell, cell determination,
• Reading 28.1, 5.5, 8.6 (eukaryotic gene
  regulation)
• Lab due 5/3
• Test/note cards Friday 5/4

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• Activator
• Complete epigenome survey

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Stem cells add new cells to a body when they
divide

• Stem cells have the ability to
• divide and renew themselves via mitosis
• Stochastic (top)
• Asymmetric (bottom)
• Daughter cells can specialize in biological tasks

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Specialized cells of the body develop from stem
cells
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A stem cell divides and forms specialized
populations of cells

• Cell Determination is committing to become one
  cell type.
• Factors affecting determination
• Cell position in the body
• Signaling
• Gene expression

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Determination gives rise to related cell
populations in a body
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• The use of stem cells has biomedical applications

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Summary

• What are the characteristics of stem cells?
• Explain how a stem cells fate is determined,
  what factors influence the future jobs these
  cells will perform?
• Discuss the potential to use stem cells in
  medical therapy
• Is using human embryos essential for medical
  therapy? Why or why not?

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Chromosomes are imprinted with epigenetic marks

• The epigenome is a pattern of chemical
  modifications on chromatin that control gene
  expression
• Imprinting involves placing epigenetic marks on
  chromosomes
• Sex cell formation
• Goal single gene expression for certain genes
  that direct development metabolism
• Male vs. female
• Diploidy is essential

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Changes to the epigenome alter how cells use
their DNA

• Histone modifications chemically modify tails
• DNA methylation CpG islands CG rich DNA

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Epigenetic marks impart a genetic memory on cells
determining their fate

• Genes can be switched on or off permanently

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Changes in epigenetics can result in disease

• (A) previously unmethylated tumor suppressor gene
  such as p53 becomes methylated suppressing gene
  expression
• (B) A protooncogene is demethylated, allowing TFs
  express the protein product.

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Epigenetic marks can change over time

• Development
• Cell differentiation
• Imprinting
• Chromosomes can be permanently tagged
• Reversible
• Age correlation
• Disease correlation

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Summary

• A cell has undergone determination to become an
  endocrine gland cell. If it is transplanted to a
  leg muscle, what do you think will happen to this
  cell?