Question

1. We’ve now discussed instances at different times in development when the same signaling pathway is activated, but its activation results in different outcomes in terms of cell fate (i.e. gene expression) at these different times. How do you imagine this is possible?

2. We talked about lin-4 miRNA-mediated translational repression as a mechanism for temporal control of lin-14 protein expression. What components would be needed, and how would they be expressed, to achieve the same via transcriptional control? Do you see an advantage of miRNA-mediated control over transcriptional control in this case?

please respond around 4 to 6 sentences for each question

Answer 1

answer a) The signalling and expression of gene is highly regulated process. Not every signalling lead to expression of every gene neither expression of every gene lead same amount of gene product. This all happen because of specific regulation for every gene. There are chromatin remodeling complexes , promoters , enhancers insulators at transcription level controlling the differential gene expression. miRNA, SiRNA and various spliceosome action also been associated with regulation of gene expression thus ultimate leading to different cell outcome.

answer b) miRNA biogenesis starts with the processing of RNA polymerase II/III transcripts post- or co-transcriptionally. miRNA gene transcribe into pri miRNA forming hairpin structure which is cleave by DROSHA forming pre miRNA. now this is exported to the cytoplasm from nucleus where it is cleave by DICER and get loaded into RISC (RNA INDUCING SILENCING COMPLEX). ADVANTAGE: miRNA mediated control is more or less specific to the gene transcripts does not require more inputs compare to transcriptional Control where input of Transcriptional factors and other various element is high for a specific gene.