Description of types of zygotic genes Flashcards
(15 cards)
How many groups of zygotic genes are there?
Three groups based on their mutant phenotypes - Gap genes, pair-rule genes and zygotic segmentation genes.
What is the phenotype for mutant gap genes?
Mutants lack large regions of the body
Name some of the gap genes.
Hunchback, kruppel, knirps, giant, tailless
Where are the gap genes expressed?
Expressed in broad domains along the AP axis (2-4 future segments)
What to the gap genes code for?
Nuclear transcription factors of the zinc-finger class
What group of zygotic genes do gap genes regulate?
Pair-rule genes
What is the phenotype for mutant pair-rule genes?
Mutants lacked portions of every other segment
Name some of the pair-rule genes
Even-skipped, odd-skipped, hairy, fushi-tarazu, paired
Where are the pair-rule genes expressed?
Activated in every other segment - 7 separate stripes
What do the pair-rule genes code for?
Mostly encode transcription factors of the homeodomain variety (60aa helix-turn-helix DNA binding domain)
What group of zygotic genes do pair-rule genes regulate?
Segment polarity genes
What is the phenotype for mutant segment-polarity genes?
Mutants show defects in every segment
Name some of the segment polarity genes
Engrailed, hedgehog, wingless
Where are the segment-polarity genes expressed?
Expressed in every segment - 14
What do the segment polarity genes code for?
- Engrailed - TF that controls expression of hh
- Hedgehog - secreted protein which regulates Wg expression in neighbouring cell
Wingless - Secreted protein that regulates gene expression in surrounding cells
Hh and Wg act as morphogens that control cell fate AP within each parasegment.
