Chapter 9 pt 2 Flashcards
How were the classes of segmentation genes named?
- _______: lacked large regions (several segments)
- _______: lacked portions of every other segment
- _______: showed defects in every segment (inversions/duplications/reversals)
identified by characterizing mutants disrupting body plan
- gap genes
- pair-rule genes
- segment polarity genes
Gap genes are activated and repressed by _______
maternal effects genes
Expression of gap genes occurs _______
before cellularization
Gap genes:
Stabilization of expression patterns occurs through repressive interactions between the gap gene products and themselves
- What are the 2 pairs of mutual repressors?
1) Knirps & Hunchback
2) Kruppel & Giant
Expression of pair-rule genes begins _______
@ 13th division
- right before cellularization
What are the 3 primary pair-rule genes?
1) hairy
2) even-skipped
3) runt
What are the 5 secondary pair-rule genes?
1) Fushi tarazu
2) odd-paired
3) odd-skipped
4) sloppy-paired
5) paired
(FOOSP)
Segment polarity genes mediate interactions between cells _______ cellularization
after
Segment polarity genes involve the production and reception of ligands in the _____ and _______ transduction pathways
Wnt
Hedgehog
Segment polarity genes contain complicated Cell-cell interactions and reciprocal signaling to establish and permanently lock-in _______
cell fates
Homeotic selector genes:
Specify the _______ of each segment now that its fate has been fully determined
characteristic structures
Homeotic selector genes:
Transcriptionally regulated by interactions with _______ and _______ proteins
- located in two regions on chromosome 3 = _______
gap proteins
pair-rule proteins
Homeotic complex (Hom-C)
Homeotic selector genes:
Appear to act as executive decision-makers that then activate as a series of _______ genes, which then directly form the tissues and organs of each segment
Realisator
Mutations in homeotic selector genes lead to bizarre phenotypes:
1) double-winged - lacks haltares - _______
2) legs where antenna should be - _______
1) ultrabithorax
2) antennapedia
When is the dorsal and ventral axis specified?
right after A/P axis
- before fertilization
explain axis formation in dorsal cells (3)
1) oocyte moves along dorsal microtubules to the anterior (-) end
2) Gurken protein moves along with it and binds to torpedo receptors on adjacent follicle cells
3) Gurken signals follicle cells to become dorsal follicle cells by inhibiting the synthesis of pipe protein
As the oocyte begins to enlarge, the nucleus is moved along the _______ microtubules towards the _______ end
dorsal
anterior (-)
_______ protein surrounding the nucleus moves along with it
gurken
Gurken binds to _______ on adjacent follicle cells signaling them to become the _______ follicle cells
torpedo
dorsal
reception of gurken by torpedo in follicle cells inhibits the synthesis of _______ protein forming dorsal cells
pipe
explain axis formation in ventral cells (10)
1) Pipe is translated
2) Pipe signal sulfates ventral vitelline protein
3) sulfated vitelline proteins bind gastrulation-defective (GD)
4) GD cleaves snake (activating it)
5) GD, snake, and uncleaved easter form complex
6) Easter is cleaved and binds to uncleaved spatzle
7) spatzle is cleaved and binds to Toll
8) Toll activation activates Tube and Pelle which phosphorylate cactus
9) cactus gets degraded and releases dorsal
10) dorsal enters the nucleus and ventralizes the cell
What is the main protein that causes the dorsal and ventral pathways to differ?
pipe
Pipe signal sulfates ventral _______ protein
vitelline
Sulfated ventral vitelline protein binds to _______
gastrulation-defective (GD)
Gastrulation-defective cleaves and activates _______
Snake
GD, Snake, and uncleaved _______ form a complex which will then cleave and activate it
Easter
Activated easter will bind to uncleaved _______ which will then cleave and activate it
Spatzle
Activated spatzle will bind to ______ receptor
Toll
The Toll receptor activates _______ and _______
Tube
Pelle
Tube and Pelle phosphorylate _______ causing it to degrade and release _______
cactus
dorsal
_______ is the actual D/V morphogen
Dorsal
- found throughout the embryo but only enters nucleus of ventral cells cuz of pathway
Dorsal mRNA is put into the oocyte by _______ cells
nurse
in Drosophila there are L/R axis asymmetries in _______ and _______ (what organs)
hindgut and gonads
