Developmental Biology and Cell Fate Specification
Building Multicellular Form
Patterning principles
Development transforms a single cell into a patterned multicellular organism through regulated proliferation, differentiation, migration, and morphogenesis. Positional information is commonly encoded by morphogen gradients, mechanical cues, and cell-cell interactions. Gene regulatory networks convert graded inputs into discrete cell fates via threshold responses, feedback, and chromatin stabilization.
What is a morphogen?
Morphogens form gradients whose concentration helps determine cell identity.
Correct answer: A signaling molecule that specifies distinct cell fates in concentration-dependent fashion
Why is developmental robustness important?
Robust systems preserve reliable patterning under perturbation.
Correct answer: Because organisms must produce correct structures despite genetic variation, environmental fluctuation, and stochastic noise.
Stem Cells and Differentiation
Pluripotency and lineage commitment
Stem cells balance self-renewal with differentiation through transcriptional circuitry and epigenetic state control. Pluripotent cells possess broad developmental potential, while adult stem cells maintain tissue homeostasis and repair. Differentiation involves progressive restriction of fate potential, often accompanied by irreversible chromatin remodeling and altered signaling competence.
Which statement best describes cell fate commitment?
Commitment generally becomes more stable as regulatory and epigenetic constraints accumulate.
Correct answer: Lineage restrictions become increasingly stable over time
What is one reason cell-cell signaling is essential in development?
Development relies on communication across tissues to establish axes and boundaries.
Correct answer: It coordinates spatial patterning so neighboring cells adopt compatible and organized identities.