Tata 2 Flashcards
(106 cards)
Lecture 1
Gap Genes.
Which genes regulate segmentation of the embryo?
Kruppel; Knirps.
What is the Kruppel gene?
Zygotically active gap gene.
What is meant by gap gene?
Mutants of gap genes show defects/gaps in patterns.
What is the effect of mutation of Kruppel?
Lack of posterior segments.
What is the effect of mutation of Knirps?
Lack of anterior segments.
Describe how Kruppel is regulated.
Transcription activated by bcd and medium concentration of hb. Repressed by high hb concentration.
What are the effects of hb on Kr in terms of expression pattern in the embryo?
Kr is expressed within a concentration window of hb. Band of Kr in the middle of embryo.
What is meant by cross-regulation? Give examples of the drosophila embryo.
Regulation not within but between pathways. Kr is repressed by other gap proteins: hb protein at anterior boundary and Knirps/Tailless proteins at posterior boundary.
What is the evidence for Kr repression by Knirps at posterior boundary?
Knirps mutants show Kr expression extending towards the posterior.
What are gap proteins?
Transcription factors. Involved in cross-regulation including regulation of pair-rule gene expression.
What are pair rule genes? Give an example.
Group of zygotic genes with related phenotype. Even skipped and fushi tarazu genes.
What is the function of pair rule genes in drosophila embryo?
Definition of body segments.
What is the function of even-skipped gene?
Definition of odd numbered parasegments.
What is the function of the fushi tarazu gene?
Definition of even numbered parasegments.
Describe the structure of segments in terms of parasegments.
Each segment is made up of the anterior part of one parasegment and the posterior of another.
How many parasegments exist in the drosophila embryo?
14
Describe the expression regulation of eve leading to the formation of the 3rd parasegment (2nd stripe).
Each eve stripe is defined separately. DNA footprinting determined that low concentration of bcd and a high concentration of hb promote transcription of eve.Eve also regulated by dissection of sequence upstream of eve gene.Eve expression repressed in 4th parasegment (2nd stripe of ftz) by the giant and kruppel genes.
Lecture 2
Homeotic Genes.
What is the function of homeotic genes?
Regulation of genes involved in morphological organisation.
What regulates homeotic genes?
Gap genes; Pair-rule genes; Other homeotic proteins.
Give examples of 3 homeotic gene mutants in drosophila.
Antennapedia; Bithorax; Postbithorax.
Describe the Antennapedia mutant phenotype.
Change of appendage. Legs instead of antennae.
Describe the bithorax mutant phenotype.
Transformation of the anterior part of a haltere to a wing.