Chapter 2 Flashcards
What is the difference between specification, determination, and differentiation?
Specification is a reversible commitment of a cell in which a different environment or different signals can cause it to differentiate along a different path, determination is irreversible commitment regardless of signals or environment because the cell is of a certain type biochemically and functionally, and differentiation is the development of a cell into its specialized type
What causes a decrease in cell potency?
A cell’s journey through the stages of specification, determination, and differentiation
How is cell specificity tested?
By placing an embryonic cell into a neutral environment and seeing if they develop into a specific cell type. If they do, it’s specified.
However, if a cell is placed in an environment that encourages its development into a different cell type such as being surrounded by cells of other types and yet it still develops into the same type of cell, then it is determined.
What is the difference between autonomous and conditional specification? Can embryos have both or only one type?
In autonomous specification, blastomeres acquire determination from egg cytoplasm. In conditional specification, they acquire determination from neighboring cells. An embryo can have a mix of autonomous and conditional cells.
What is a fate map?
The mapping of an embryo based on statistical likelihoods into which of its cells will form which germ layers and structures.
What is the difference between the outcomes of autonomous specification of blastomeres and conditional specification of blastomeres?
Autonomous: Mosaic development. isolated blastomeres only produce part of the organism
Conditional: Regulative development, if split in two each will produce a complete embryo
Where do autonomous and conditional specification predominate?
In invertebrates and vertebrates respectively, though conditional specification occurs in a few invertebrates.
What is syncytial specification? Where does it predominate?
The division of nuclei into many many copies without cell membranes until later. Cycle 14 makes cell membranes. It predominates in insects.
What is a morphogen?
A long-range signalling molecule, it forms a concentration gradient in the embryo and affects cell differentiation/specification depending on the concentration. Ex: bicoid/caudal in drosophila
What is a determinant? Why can’t transcription factors in humans serve as morphogens?
A determinant influences cell fate in the cell it is produced in.
TFs in humans cannot serve as morphogens because they cannot diffuse out of the cell membrane to form the gradient seen with morphogens.
