Basic Stuff Lecture Flashcards
How genome of single cell turned into multiple functions of many cell types in whole organism
Regulation of gene transcription
Post trans modification
Introns exons
Splicing
mRNA
Translation
Regulated though
Whether or not transcribed by RNA pol II
TFs bind enhancer/silencer elements - dictated y or n transcription to diff genes
Urchin zygote onwards
Zygote
Divisions
4 cell
8 cell
At 8 cell some cells are smaller than neighbours / something about them must be different
These cells push into centre of hollow (invaginate) forming layers
Echinoderm so has all 3
Deuterostome so anus develops from the blastopore this forms
Invertebrate (drosophila) development basic
Egg laid after mating
Embryo begins to develop feeding on yolk
Has larval forms 1, 2, 3, instar
Then pupates
Suddenly hatched in adult form
Holometsbolois insect as is dipteran
Asymmetric cell division
Two diff Markers in mother cell
One marker in each daughter - inherit diff markers
This distinct protein inherited confers cell type
Establishing spatial pattern of gene expression nematode development
PAR-2 protein in fertilised egg
Localised info in posterior end
Single division along plane
2 daughters don’t appear different but stain for diff proteins
Only one daughter will inherit PAR-2 as it was only on one side of the mother cell
Has consequences in subsequent divisions
Par-2 alters how the spindle MTs form in the posterior daughter altering the plane of division
Causes the par2 cells to shift orientation and ends up with more different cues they can use
Cell differentiation by interaction with environment
With other cells
And with secreted molecules
Causes change in gene expressuon
Called INDUCTION
Have two diff cell
Blue gives rise to blue
Red to red
Put r and b together get yellow
Only in presence of 2 distinct cell types does the 3rd arise
B have induced r to become Y
Induction in nematode development
Consequences of the orientation change by asymmetric Par-2 inheritance
End up with certain orientation of cells
Rightmost (P) cell induces topmost cell to be different to its neighbours
Inheritance of one protein par2 will set off cascade of cell events causing diff differentiation events
In C elegant cell lineage is invariant
Complete lineage history of each cell can be traced back to zygote
But induction is also occurring
How do these reconcile?
As long as cell lineage doesn’t change after it is determined even if determined by induction the lineage history remains intact
Even if lineage is not pre determined
Fate mapping/lineage tracing
Inject heritable dye at early stage where cells are indistinct
And can trace what cells contain this dye when they look distinct
Can see what cell types this one gave rise to
The fates/lineages arising from this cell
Cell transplantation/grafting
Labile = susceptible to change
Find out if certain cell type is pre determined to become another and always will
Or if it is susceptible to change
Take cell from eye primordium of yonder donor
And graft it to belly primordium of host neurula
These donor cells can become belly epidermis
But take eye primordium from older donor
Will not become belly epidermis and will come ectopic eye
Was not determined yet in rounder donor
But was already determined into eye lineage in Older one
Would have to graft eye primordium to to other parts with similar lineages to see if it completely determined yet
Transplanting from one part of developing limb to another
Take part from one part of limb
To another with later stage signals present
Will change to match that later part of the limb
HENCE commitment/determination is progressive
