Molecular Patterning during development Flashcards
What is meant by the “generative program” in cell diffrentiation?
It refers to the developmental rules that guide how cells change identity and form different tissues during development.
How do regulatory proteins act in cell differentiation?
Regulatory proteins function together like a committee to control gene expression, influencing cell fate.
How can many cell types arise from few regulatory proteins?
Through combinations of a small number of proteins working together in different ways — known as combinatorial control.
Define ‘cell fate’ in developmental biology.
The final differentiated state a cell is expected to reach under normal conditions.
What does ‘potency’ refer to in cell biology?
The range of different cell types a particular cell can give rise to.
What is ‘differentiation’?
A process where cells become specialized, adopting specific functions and characteristics.
How do differentiation, fate, and potency relate?
Potency describes potential, fate is what will happen, and differentiation is the actual process of becoming that fate.
What is stable differentiation?
Terminally differentiated cells maintain their identity permanently (e.g., neurons, muscle cells).
What is a common example of stable differentiation?
Muscle cells and neurons which do not revert to other types once differentiated.
Can cells de-differentiate?
Some cells can de-differentiate in certain species (like amphibians), but most human cells cannot under normal conditions.
What is the first stage of commitment called?
Specification – the cell is biased toward a specific fate but still reversible.
What is the second stage of commitment?
Determination – the cell’s fate is fixed, even if placed in a different environment.
How do specification and determination differ?
Specification is flexible and reversible; determination is rigid and irreversible.
What are intrinsic mechanisms of cell specification?
Internal cues, such as inherited transcription factors or cytoplasmic determinants.
What are extrinsic mechanisms of cell specification?
External signals like cell-cell interactions or secreted morphogens that guide fate.
Give an example of extrinsic cell specification.
Morphogens like Sonic Hedgehog (Shh) influencing limb development.
Why is gene expression central to differentiation?
Different cell types express different sets of genes, resulting in unique functions and forms.
What determines which genes are expressed in a cell?
Combinations of transcription factors and epigenetic regulation (like histone modifications).
What is combinatorial gene regulation?
The use of various combinations of transcription factors to activate specific gene sets.
What is bivalent chromatin?
A state where both activating and repressive histone marks exist at a gene’s promoter.
Why is bivalent chromatin important in stem cells?
It keeps genes “poised” to be either activated or silenced depending on the differentiation signal.
What does bivalent chromatin allow in development?
Flexibility for stem cells to commit to multiple potential lineages.
What are the two main processes of bone formation?
Intramembranous ossification (flat bones) and endochondral ossification (long bones).
What happens in endochondral ossification?
Cartilage is formed first and then replaced by bone tissue.
