concepts and terminology Flashcards
what causes a change in cell fate?
changes in cell fate is a consequence of the molecular character of particular cells
how are these changes controlled?
Mosaic development - information inherited by parent cell to tell it what to become
regulative development - the cell is influenced by it’s surroundings, or position, within the embryo - a cell does not know what it will become until it has received a particular type of information or arrived at a particular location which determines its future
explain Roux’s experiment
Roux has destroyed one cell of a 2 cell frog embryo but did not remove it resulting in the development of only one half of the embryo. this was to represent mosaic development however it can be perceived as regulative development as its environment affected it. The choice of development can be determined by how you do or interpret the experiment
what is robustness?
a cell/ particular group of cells is damaged during development and the cell is able to detect/ sense that and compensate for it
What does Driesch’s separation of sea urchin blastomeres demonstrate?
Driesch’s separation of sea urchin blastomeres demonstrates regulative development
What is fate?
fate is what will normally happen to a cell during development
What does commitment comprise of?
Specification - what tissues will develop in an autonomous (neutral) environment
Determination - an irreversible change in potential
what is differentiation?
A restriction of potential with molecular/ biochemical changes - term often used for mature cell types
What is potential or potency?
the range of tissues which a cell can give rise to
what is totipotent?
can give rise to all tissues (a fertilised zygote up to an 8 cell stage)
What is pluripotent?
Can give rise to many tissues
What is orthotopic graft?
Transplantation of a tissue or organ into its normal anatomic position
What is heterotopic graft?
Transplantation of a tissue or organ into a position that it normally does not occupy
During an experiment using a labeled donor:
What will happen if you graft the labeled donor cells onto an embryo via orthotopic graft?
It will end up in its normal fate
During an experiment using a labeled donor:
What will happen if you isolate the tissue?
You can find its specification
During an experiment using a labeled donor:
What will happen if you heterotropically graft the labeled donor cells onto an embryo at its early stage?
it will lead to no determination as the early tissue isn’t committed
During an experiment using a labeled donor:
What about at a later stage?
Determination will occur as the early tissue is committed
What is induction?
Process by which cells and tissues in embryos direct the development of adjacent cells
What does restriction in potential depend on?
Restriction in potential often depends on inductive interactions from neighbouring cells
What is competence?
competence is the ability to respond to an inductive signal
What does Spermann and Mangold’s classic 1924 experiment define?
Spermann and Mangold’s classic 1924 experiment defined an inducing tissue with organiser activity
What does permissive induction create?
Permissive induction would create the environment where other factors can act to cause a tissue to be induced
What are the two types of instructive induction?
Appositional - where the instructions is passed by the close apposition or bringing together of 2 different tissue types
Morphogen gradient - localised signal of morphogen which is diffusible from its localised source. as a result of this diffusion, there are different concentrations of morphogen across the embryo
What is a morphogen?
A diffusible molecule that triggers different cell fates at different concentrations
What can morphogens provide?
positional information within the embryo
What do homeotic/ hox genes confer?
Hox genes confer positional identity
What does the drosophila antennapedia have instead?
Has legs instead of antennae
What do homeotic genes do?
Regulate the development of anatomical structures
What do Turing’s reaction - diffusible model propose?
This proposes a diffusible activator that activates a diffusible inhibitor itself
What are Turing’s patterns?
If the activator diffuses, it induces an inhibitor that also is diffusible. This inhibitor inhibits the activator. As there’s no activator now there’s no need for an inhibitor so it disappears.
What are the steps to form a protein?
Regulatory region assembles RNA polymerase to generate RNA. RNA is transcribed and produces hnRNA containing both introns and exons. RNA is spliced leaving exons with a 3’ A tails and 5’ cap. RNA is translated then into a protein.
What are the changes in cell fate reflected by?
Changes in cell fate are reflected by changes in gene expression
What secretions allow cells to communicate?
secreted factors and other signals allow cells to communicate
What other levels does additional control occur at other than gene expression?
Additional control at level of translation, post translation, epigenetic changes
