Taylor Lectures
Terms
- Symmetric Cell Division
- Daughter cells are initially identical to each other and their mother cell. They become distinct from each other through exposure to different environmental conditions.
- Asymmetric Cell Division
- Daughter cells are initially different from parent cell, usually due to the asymmetric localization of regulatory molecules.
- Stem cells give rise to...
- ...both; more stem cells (to maintain stem cell population) and stem cells with limited developmental ability that will eventually become progenitor cells.
- How are tissues maintain?
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By associated population of stem cells.
For example:
The cells of the intestinal epithelium continually regenerate from a stem cell population located in the crypts
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All cells of the mammalian 8-cell embryo are identical and each can give rise to a new animal.
However, at the 64 cell stage, two cell types have formed.What are they?
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Trophectoderm - forms the extraembryonic tissues
Inner cell mass - forms the embryo
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The inner cell mass forms three germ layers.
What are they and what do they form?
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Ectoderm – neural and epidermal cells
Mesoderm – muscle and connective tissue
Endoderm – gut epithelia
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What are Heterochronic mutants?
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Result from a developmental event typical of one stage of development that occurs too early (precocious development) or too late (retarded development)
For Example: Premature occurrence of a division cycle that yields one cell that differentiates
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How could you screen for myogenic genes?
- By treating C3H10T firbroblasts with 5-aza-deoxycytadinem,subsuquently extracting total mRNA, and reverse transcribing to labeled cDNA. Next hybridize this labeled cDNA with the mRNA from untreated cell and discard all ds Hybrids. This will leave you with
- Name the steps and the required Muscle Regulatory Factors/Muscle Enhancing Factors necessary in the myogenic pathway.
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Somite --> Myoblast
(MyoD &/or Myf5)
Myboblast --> Myotube
(Myogenin & MEFs)
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What are Trophic Factors?
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Intercellular survival signals that cells require to stay alive.
In their absences cell's activate a suicide program.
- Name 3 general classes of proteins involved in controlling cell death and describe their functions.
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Killer Proteins are required to initiate the apoptotic pathway
Destruction Proteins break down the components for the dying cell
Engulfment Proteins allow phagocytosis of the dying cell by
- How does Apoptosis differ from Necrorsis?
- Apoptosis is a highly orchesrated form of cell death where cells commit suicide and their membrane packaged bits are phagocytosed. Necrosis is the process where cells swell and burst, releasing their contents which can da
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What factors influence the number and survival of motor neurons that innervate a particular target tissue?
- The size of the muscle target field. By removing the limb of a growing embryo researchers observed that the number of motor neurons decreased. In contrast when extra tissue was grafted on a much larger number of motor neurons grew there.
- What is NGF?
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Nerve Growth Factor
A neuron specific trophic factor (neurotrophin) that exists as a homodimer and binds to tyrosine receptor kinases, promoting neuron survival.
Each neurotrophin is responsible for survival of a spec
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Describe the regulatory relationship between the three ced apoptotics genes.
- ced-4 binds to the ced-3 protease to activate it, which will then initiate apoptosis unless ced-9 binds to ced-4 and prevents it from activating ced-3.
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What would be the result of a LOF mutation of ced-3?
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Cells fated to die would survive and differentiate.
- What would be the result of a LOF mutation of ced-4?
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Cells fated to die would survive and differentiate.
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What is the human homolog of ced-9 and what is its function?
- Bcl-2 is an anti-apoptic protein. Like ced-9, it contains a single transmembrane protein and is located in the outer membrane of mitochondria, nucleus and the endoplasmic reticulum; and act as sensors and regulate the apoptotic pathway in
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Describe Caspases and their role in apoptosis.
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Caspases are cysteine aspartases and use a cystein monomer to cleave proteins at a specific aspartate residue.
When Cytochrome-C binds to the Apaf-1 adapter protein the caspase cascade is initiated and leads
- Describe events leading to apoptotis
- In the absence of trophic factor a proapoptotic protein binds to Bcl-2 in the mitochondrial membrane an ion channel opens allowing an influx of ions into mitochondria. This releases Cytochrome C which will bind to the Apaf-1 adapter protein, which initiat
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What is Heterochronic Mutant?
- A heterochronic mutant results if a cell divides too early or too late during embryogenesis. The result of this will be that one of the newly formed daughter cells will die and the cell lineage or tissue that daughter cell would have given rise to will ne