Cell interactions and cell movements in development I Flashcards
(33 cards)
What is morphogenesis?
Generation of form–> development of an embryo from an egg cell
Key cellular properties involved in animal embryonic form?
Cell adhesion, cell motility, cell shape
What categories can cells in embryos be classified into?
Epithelial and mesenchymal
Epithelia?
A sheet of cells that sit on top of a specialised extracellular matrix
What is the extracellular matrix that the epithelium sits on top of?
Basal Lamina
Mesenchyme?
Composed of scattered cells surrounded by loose extracellular matrix
What is a cell junction?
A specialised site on a cell at which it is attached to another cell or the extracellular matrix
Which cell adhesion molecules do adherens and desmosomes use?
Cadherins
Accessory proteins for adherens junctions?
Alpha and beta catenin
Accessory proteins for desmosome junctions?
Plakoglobin, desmoplakin
Where on the cytoskeleton do adherens junctions link to?
Actin filaments
Where on the cytoskeleton do desmosome junctions link to?
Intermediate filaments
Which cell adhesion molecules do focal adhesions and and hemidesmosomes use?
Integrin
Where on the cytoskeleton do focal adhesions link to?
actin
Where on the cytoskeleton do hemidesmosome junctions link to?
intermediate filaments
What are cadherins reliant on?
Ca2+–> w/o it they won’t gold the cells together
What happens if some ectoderm and endoderm are taken from en embryo ans stuck together?
Over time they pull apart until only a strip of cells holds them together
Why do ectoderm and endoderm pull apart in vitro?
During development the endoderm and ectoderm are separated by the mesoderm, and so dont like to stick to one another
Effect of mixing mesoderm and ectoderm cells together?
Eventually they form a ball and self sort–> i.e. ectoderm clumps in the middle and the mesoderm is round the outside
Why do ectoderm cells go to the middle and mesoderm cells go to the outside of a ball when mixed?
They differentially express cell adhesion molecules that given them different affinities for one another
What drives cleavages in embryonic cells?
Actin filaments forming a contractile ring around the cell, splitting the cell into two
Outcome of apical constriction?
Causes the cell to become wedge shaped
How do cells change shape when migrating?
Cell sends out processes/lamellipodia
Actin filaments form to push the edge of the cell out
What does cell motility require?
Changes in adhesiveness/shape
