Lecture 5: Tissue Patterning Flashcards
(18 cards)
after assuming a shape how do multicellular organisms continue to divide and become specialized cells with different functions
through a process of differentiation where specialized cells are acquired through genome expression. Simply saying, different cells acquire different fates
how is cell fate acquired
- Asymmetric division (child cells are born with different fates)
- Symmetric division (child cells are the same but acquire different fates through perception of a signal)
how does asymmetric division contribute to specialized cell fate?
when cells form and begin to divide, some cell fate markers are unevenly distributed and one daughter cell will inherent more of the cell fate markers for a specific type of cell
how does symmetric division contribute to specialized cell fate
- lateral inhibition
- induction by diffusible signals
lateral inhibition
this is where tiny or short lived differences between daughter cells are amplified leading to specialized cells
Example of lateral inhibition
in flies, notch signaling is when some cells develop into sensory bristles.
take two identical daughter cells, delta some type of receptor signal. it will inherently activate notch on cell b and notch will eventually inhibit delta of cell b. inactive delta will activate notch on cell a and notch will inhibit delta on cell A.
The two cells will enter a competition where one specialized cell will be inhibited and the other cell will become a specialized cell.
in what scenario in notch signaling will one cell continue to develop into a specialized cell and the other will be inhibited.
where active notch will lead to an inactive notch of the second cell. The cell with the inactive notch will proceed further to become the specialized cell
induction by diffusible signals
this is when organizer cells secrete a signal (morphogens) and nearby cells will react to it by taking it on new fates
Do all cells react the same to the same morphogens.
no different cells can turn into different things from the same morphogens depending on its concentrations
totipotent
cells that become any type of cell
pluripotent
cells can be become any adult cells
multipotent
cells can become multiple cell types
looking at a living organism how can we get different cell segments?
through differential signaling where the same morphogen can affect two cells differently
what is the essential process that allows the body to be divided into smaller parts
Segmentation
describe the regulatory hierarchy of segmentation
- first differentiation is posterior/anterior
- definition of the is head, thorax, and abdomen
- Further specification and segmentation of the head, thorax, and abdomen
4.polarity of the segments - body parts develop from the segments
in flies, which genes determine which body parts will develop from which segments
hox genes
how many copies of the hox complex do humans have
4
what do hox genes encode
transcription factors
