12 Questions
What are the three main classes of maternal effect genes that control embryonic patterning in Drosophila?
The three main classes of maternal effect genes are: 1) Anterior specification (e.g. Bicoid), 2) Posterior specification (e.g. Nanos), and 3) Both ends specification (e.g. Torso).
How do maternal mRNAs specify the terminal regions of the embryo?
Maternal mRNAs such as Torso mRNA are laid down by the mother in a graded fashion, and these mRNAs specify the terminal regions of the embryo.
Describe the role of the Torso protein in terminal specification.
The Torso protein is a receptor tyrosine kinase that is ubiquitously expressed but only activated at the termini of the embryo, via its activator Torso-Like. Torso-Like protein controls the local secretion of Trunk, which acts as the ligand for Torso.
How do the maternal effect genes Bicoid and Nanos set up the anterior-posterior axis in Drosophila?
Bicoid and Nanos mRNAs are deposited at opposite ends of the embryo. They encode transcription factors that act via a gradient mechanism to set up the anterior-posterior axis, with Bicoid specifying the anterior and Nanos specifying the posterior.
Explain the combinatorial effect of the maternal effect genes Bicoid, Nanos, Caudal, and Hunchback in regulating target gene expression.
The combinatorial effect of different levels of Bicoid, Nanos, Caudal (maternal effect), and Hunchback (maternal effect and zygotic gap gene) along the length of the embryo dictates the expression domains of target genes (gap genes).
What are the phenotypes of Bicoid and Nanos mutants in Drosophila embryos?
Bicoid mutants result in embryos with no head region, while Nanos mutants result in embryos with no tail region.
What is the primary role of the Torso protein in the Drosophila embryo?
It is a receptor tyrosine kinase that is activated at the terminal ends of the embryo.
What is the primary function of the maternal effect genes Bicoid and Nanos in establishing the anterior-posterior axis in Drosophila?
They form opposing concentration gradients that specify the anterior and posterior regions of the embryo.
What is the primary role of the maternal effect gene Caudal in the Drosophila embryo?
It is involved in the repression of the Hunchback gene by Nanos.
What is the primary phenotype observed in Bicoid mutant Drosophila embryos?
They lack the head region and have no anterior structures.
What is the primary function of the maternal effect gene Torso-Like in the Drosophila embryo?
It controls the local activation of the Torso receptor tyrosine kinase at the terminal ends of the embryo.
How do the maternal effect genes Bicoid and Nanos regulate the expression of target genes in the Drosophila embryo?
They regulate the translation of target mRNAs by acting as either transcriptional repressors or activators.
Explore the roles of maternal effect genes such as Bicoid, Nanos, and Torso in specifying anterior, posterior, and terminal regions of the embryo. Understand how mRNA gradients established by the mother influence polarity and terminal specification in embryonic development.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
