Flashcards in Lect. 10 - Dev. Genetics II Deck (21):
Hierarchy order of genes in drosophila development
Egg polarity genes (maternal effect genes), segmentation genes, homeotic genes
maternal effect genes aka egg polarity genes
important in the establishment of the dorsal-ventral and anterior posterior axes in the fruit fly
egg polarity genes that establish the ventral-dorsal axis include:
dorsal, cactus, toll
egg polarity genes that establish the anterior-posterior axis include:
bicoid, nanos, hunchback
why are egg polarity genes also called maternal effect genes?
even though their mRNAs migrate to the eggs and are translated after fertilization, they are transcribed into mRNAs in the ovary BEFORE fertilization
how do egg polarity genes work?
by setting up protein concentration gradients
a protein that varies in concentration and causes different developmental responses as a result of the concentration differences
Where are dorsal, cactus, and toll genes expressed?
in the ovary
binds dorsal protein and traps it in the cytoplasm
leads to the degradation of the cactus protein, allowing dorsal protein to move into the nuclei of the ventral cells
expressed in the ovary; regulates expression of genes responsible for posterior structures; inhibits translation of hunchback mRNA
express in ovary; regulates expression of genes responsible for anterior structures and stimulates hunchback
transcribed after fertilization; Gap genes, pair-rule genes, segment-polarity genes
what regulates the segmentation genes?
bicoid and nanos protein gradients
delete adjacent segments
delete sam part of patter in every other segment
afftect polarity of segment
determines the identity of individual segments; expressed after fertilzation; contain homeobox; antennapedia and bithorax complex
what activates the homeotic genes?
concentration of products of gap, pair-rule, and semgnet-polarity genes
affects development of head and thorax