BIO 448
MOLECULAR BIOLOGY OF
DIFFERENTIATION
Cascade effect…
• Drosophila development is the result of a series of transcriptionally controlled events
Bicoid and nanos protein gradients provide positional information
• The concentration of bicoid protein is highest at the anterior end of the embryo
• While bicoid protein affects transcription;
nanos affects translation.
• hunchback gene
• krüppel gene
• The interactions of the proteins encoded by the gap genes determine the regions of the larval body in Drosophila.
• The hunchback and Krüppel proteins overlap and form a border between the two regions.
• Homeotic genes give different segments with different structural and functional features.
Each homeotic gene is expressed in a characteristic part of the embryo.
• Homeotic mutations cause large-scale effects
• During normal development, homeotic genes show their effects later than segmentation
genes and give each segment its distinctive character: called as selector genes.
• Homeobox-containing genes encode transcription factors
