Question

two separate questions and I need two separate answers please...

1-Separation of the fly embryo into segments and separation of neuroblasts into different types are both dependent on transcriptional cascades. What is a transcriptional cascade (1 sentence)? Explain what is different (conceptually) in the transcriptional cascades in the two developmental scenarios (1 sentence).

2) In your opinion, is lateral inhibition similar or different from induction? State and support your argument in 1-2 sentences.

Answer 1

What is a transcriptional cascade (1 sentence)?.

The initial signal induces the expression of the gene of the transcription factor, this transcription factor induces the expression of other transcription factors and this ultimately results in tight control and expression of the target gene. This multistep process is known as a transcriptional cascade.

The difference in a transcriptional cascade of embryo segmentation and separation of neuroblast:

In fly embryo segmentation: The transcriptional cascade is initiated by pre-existing transcript (maternally provided during fertilization) like caudal(cad), hunchback(hb), nanos(nan), bicoid(bcd), etc

Transcriptional cascade in neuroblast: This is not initiated by the maternally provided transcript. it is sequentially expressed four transcription factors: Hunchback (Ikaros class) —> Krüppel (zinc finger class) —> Pdm (Pou/homeodomain class) —> Castor (zinc finger class).

Is lateral inhibition similar or different from induction?

Both are different

Explanation:  In Lateral inhibition process Notch signaling inhibits neighbors in a pool of initially equivalent cells where Lateral induction is a process by which Notch signaling induces neighbors in a pool of initially equivalent cells to adopt a common fate.