Drosophilia: Hox genes (L16) Flashcards
Do drosophilia have a fixed number of segments, with each segment having a defined regional identity?
YES
What makes up the head section of a drosophilia?
- Mandibular
- Labial
- Maxillary
What makes up the thorax section of a drosophilia?
T1, leg 1, no wing
T2, leg 2, wing
T3, leg 3, haltere
What makes up the abdomen section of a drosophilia?
A1-A8
What do adult ectodermal structures develop from?
Imaginal discs
What are imaginal discs?
Pad of undifferentiated cells in larva, each has its own fate and fate map.
What is meant by trans-determination?
Discs can be subdivided and implanted into host embryos and will usually develop according to type but occasionally give rise to unexpected structures.
Mutant flied observed in the 1890’s showed what?
Inappropriate appendages on certain segments; HOMEOTIC MUTANTS.
- ‘antennapedia’- antennae converted to legs
- ‘bithroax’ anterior compartment of haltere transformed into anterior wind
Homeotic mutations mapped by Ed Lewis showed existence of what..
clusters of related genes on a chromosome.
Hox gene clusters thought to have arisen by tandem gene duplication.
What is co-linearity?
The linear sequence of genes on chromosome is the same as the order of expression in the fly
Sequencing of the Hox gene revealed a what…
homeobox
What is a homeotic gene?
A gene which defines a region or position in the embryo.
What is a homeobox?
A region of DNA in homeotic genes that encodes a DNA-binding domain called the homeodomain.
What is a hox gene?
a family of the homeobox- containing genes that are also part of homeotic gene complex
What is the Hom-C complex?
The collective name of the antennapedia and bithroax gene clusters?
What is the structure of the homeobox?
180 base pairs encoding for the homeodomain, 60 amino acid sequence includes a helix-turn-helix motif.
Distal-less does what?
activates gene pathway for limb formation, regulated by ULTRABITHROAX.
Decapentaplegic does what?
triggers cell shape changes in the gut, is regulated by ULTRABITHORAX
Reaper does what?
Apoptosis, regulated by DEFORMED
Dapentaplegic does what?
Prevents cell changes in posterior positions, regulated by adominal-B
