Devpt Of Multicell Organisms 1 Flashcards
What does it mean for cells to have a memory?
They retain record of signals their ancestors received during embryonic development.
Ectoderm
Precursor of the nervous system and the epidermis
Endoderm
Precursor of gut, lung and liver
Mesoderm
Precursor of muscles and connective tissue
Gastrulation
Transformation of a hollow sphere of cells into a structure w/ a gut
What are the two classes of proteins most important for development?
Cell adhesion/ cell signaling proteins and Gene regulatory proteins
Where are the instructions for producing a multicellular animal contained?
In the non-coding regulatory DNA associated a/ each gene
In DNA, what serves as the biding sites for gene regulatory proteins?
Regulatory elements within the DNA; regulatory DNA defines the sequential program for development
What makes one organism different from another and provides uniqueness?
Non-coding sequences
When do cells make developmental decisions?
Long before they show any outward sign of differentiation
Define “determined”
Cells that are fated to develop into a specialized cell type despite changes in environment
Define “completely undetermined”
Cells that can change rapidly due to alterations in environment
Define “committed”
Cells that have some attributes of a particular cell type but can change with environment
What does it mean for cells to be regionally determined?
Before acquiring a particular fate, they express genes that are markers of their location. The position specific character of a cell is called positional value
What are the most important environmental cues?
Signals from neighboring cells
Define inductive signaling
Induction of a different developmental program in select cells in a homogeneous group leading to altered character
Positive feedback
System starts homogeneous and symmetrical then the environment imposes weak asymmetry. Positive feedback amplifies this effect. Broken asymmetry is all or none and irreversible
What does positive feedback provide the cells with?
Memory
What is a morphogen?
A long range inductive signal that imposes a pattern on a field of cells
What is the gradient formed by in morphogens?
- Localized production of an inducer that diffuses away from its source and 2. Localized production of an inhibitor that diffuses away from its source and blocks the action of a uniformly distributed inducer
Signaling pathways
Handful of conserved family of proteins; ultimately result of inductive events is change in DNA transcription. Some genes turned on, other turned off. The response depends on spatial and temporal expression of different sets of genes.
Signaling pathway: RTK. What are the ligands?
EGF; FGF (Branchless); Ephrins
Signaling pathway: TGF-beta superfamily. Ligand family?
TGFbeta; BMP(Dpp); Nodal
Signaling pathway: Wnt. Ligand family?
Wnt (wingless)
Signaling pathway: Hedgehog. Ligand family?
Hedgehog
Signaling pathway: Notch. Ligand family?
Delta
What controls development?
Gene expression
