Term
| What are the 5 types of induction and describe each |
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Definition
1. Inductive signaling - cell releases signaling proteins that bind to neighbor cells
2. Gradient signaling - different cellular processes are stimulated based on concentration of a signal molecule released by a cell (concentration is higher closer to the releasing cell)
3. Antagonistic - One cell releases a signaling promoting a cellular process and another releases one counteracting this. The concentration of the pro vs. con molecules determine what a receptor cell will do
5. Cascade - One cell induces another, which induces another, which induces another, etc.
6. Combinatorial - Cells releasing multiple signal compounds combine to induce cellular processes |
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Term
| Explain the segmentation process of embryos and how the characteristics of each segment are determined in flies |
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Definition
1. Division into smaller and smaller regions within the embryo by different subfamilies of genes, segmenting the embryo along its cranial-caudal axis.
2. A family of genes called homeotic genes (ex. Hox, Pax) are expressed and the spatial and temporal expression defines the characteristics of each embryo segment (differentiation into body parts) |
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Term
| Explain the function of homeotic genes in human development and how they accomplish body part differentiation |
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Definition
| Homeotic genes are expressed throughout the body in segments ( ex. Pax1 from the head down, Pax2 from right below Pax1 down, Pax3 from right below Pax2 down, etc.). The gene immediately downstream is antagonistic of the one upstream (ex. Pax2 deactivates Pax1, Pax7 deactivates Pax6). This leads to expression of specific homeotic genes in specific portions of the embryo, which serve as transcription factors which lead to differentiation of body parts along the cranial-caudal axis |
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Term
| What are the 5 common steps in signaling pathways? |
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Definition
1. Reception (binding)
2. Transmission (from outside to inside of cell, usually through phosphorylation)
3. Amplification (multiple transmission cycles)
4. Outcome (usually gene expression)
5. Termination of signal (some form of feedback) |
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Term
| What are the major steps in the growth factor signaling pathway? |
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Definition
1. Binding of signal to recptors
2. Activation of Ras (via phorphorylation)
3. Activation of MAP-kinases (uses ATP)
4. Change in gene expression and protein activity |
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Term
| What are the major steps involved in the TGF-beta signaling pathway? |
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Definition
1. Binding to surface receptor
2. Binding of Smad4 to Smad2/3 complex
3. Migration of complex to the nuclues
4. Activation of gene expression |
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Term
| Give 2 examples of diffusible morphogens that regulate cell behavior |
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Definition
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Term
| Describe the major events in the Wnt signal pathway |
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Definition
1. Bind to surface receptor
2. Activation of Dishevelled
3. Stabilization of catenin
4. Expression of genes |
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Term
| What is lateral inhibition and what cell surface molecule helps initiate it? |
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Definition
A cell that has differentiated into a certain fate prevents its neighboring cells from doing the same.
Notch. |
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Term
| Describe the process of left-right asymmetry and how it leads to the development of particular organs in particular places in the body |
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Definition
| Beating of cilia in the primitive node drive a current of extracellular fluid. This drives the asymmetric expression of Nodal on the left side of the body, which drives the formation of organs on the left side (lungs, heart, gut, stomach, spleen) |
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