Topic E1 Flashcards
What is pattern formation:
- The process in which there is a complex organisation of cell fates in space and time.
What 2 things does pattern formation require?
- Differential gene expression
2. Signalling between cells (signalling molecules)
What is cell fate?
- The developmental destination of a cell if left undisturbed in the embryo
What are the two main processes in determining cell fate?
- Cell fate commitment
a. specification
b. determination - Differentiation
What is cell fate restriction?
- When the fate of the cell becomes restricted
Describe the two factors within cell fate commitment:
a. Specification: the fate of the cell is biased but not irreversible. The cell is capable of differentiating autonomously into its specified form in a dish only- if the cell is transplanted to another part of the embryo it can change fate (as it is exposed to different factors)
b. Determination: the fate of the cell cannot be reversed. The cell will differentiate autonomously according to its determined cell fate both in a dish and if placed in another region of the organism.
What is the process of differentiation?
- The expression of developmental fate in which the cell adopts its final phenotype
- Differentiated cells express genes to form proteins to allow them to carry out their function and other exit the cell cycle
- Differentiated is usually a irreversible process (unless forced e.g. iPS cells)
What is cell fate restriction governed by?
- The cells genome (gene expression)
- The cell’s history (the factors it has been exposed to- chromatin marks)
- Interaction with its neighbouring cells
What is the difference between epithelial and mesenchymal cells?
Epithelial cells: are tightly connected to eachother in sheets/tubes, sit on a basement membrane, cannot move independently, are polarised and display epithelial marker genes e.g. cytokeratin
Mesenchymal cells: are not joined to other cells and are free to move independently around the ECM. They are not poalrised and they express mesenchymal marker genes e.g. Vimettin
What is a fate map?
- A diagram that maps adult tissues or structures to the regions of the embryo that gave rise to that tissue/structure
What are the advantages and disadvantages of invertebrate models?
Advantages:
- Easy to keep
- Rapid life cycle
- Fate of most/all cells known
Disadvantages:
- many aspects of development and anatomy are not conserved with humans
What are the advantages and disadvantages of lower vertebrate models? e.g. zebrafish
Advantages:
- Easy to keep
- Easy to manipulate and access (embryo develops outside maternal body)
Disadvantages:
- Distant from humans- some features not shared
What are the advantages and disadvantages of avian models? e.g. chickens
Advantages:
- A higher vertebrate (closer to humans)
- Easy to obtain and study (embryo develops in ovo)
Disadvantages:
- longer life cycle
- transgenic strategies lag behind those in mice
What are the advantages and disadvantages of mouse models?
Advantages:
- Mouse is a mammal- many of the same organ systems and diseases as humans
- Advanced transgenics available
Disadvantages:
- Embryos develop in utero (access is difficult)
- models can sometimes have different phenotypes as humans to disease
Describe the difference between descriptive studies and manipulative studies:
Descriptive studies:
- Observe and study the development of an organism e.g. fate mapping, histology studies etc.
Manipulative studies:
- Altering a system and observing the effects
