Question

a) A cell requires the ability to sense and respond to its environment on a transcriptional level. List a mechanism as to how this might be achieved and an example process where this would be important?

b) Proteases are enzymes that degrade other proteins. Many proteases inside the cell are in the lysosome. Why do you think this is so and what properties, if any, of the lysosome contribute to regulation of protease activity inside the cell?

Answer 1

A) transcription factors activity in response to environmental signal is the primary response at the transcriptional level or gene expression level. Environmental signals activates transcription factors that binds with either enhancer of a gene loci to upregulate some genes or with repressor region to downregulate the expression of some genes. Combination of transcription factors are involved in the regulation in the transcriptional level. Once environemental signal sensed by the cells receptor it activates cascade of reactions to activate transcription factors that enter into the nucleus to upregulate or downregulate the gene expression

For example in lac operon of bacteria, the lactose source is identified and CRP levels gets high that activates the lac operon to synthesize lac genes.

B) lysosome are organs composed of more than 40 enzymes including proteases, lipase and nuclease to degrade or breakdown specific to each cellular components . Lysosomal proteases composed of aspartic protease, serine/cystein protease and each specific for different kind of proteins upon recognition