Question

c)   Identify which carbon source(s) is/are inducer(s) and repressor(s) (3 m)

The carbon source that is an inducer is maltose and carbon sources that are repressors are glucose and 2-deoxy-D-glucose.

d) Discuss how do inducer(s) and repressor(s) in answer (c), control the transcription and expression of alpha-glucosidase. (10 m). Hint: You may want to support your answers with reference to articles or books.

Please answer D with reference to articles or books.

Answer 1

Thanks for asking the question.

c)

Basically Maltose and isomaltose are the disaccharides which are the products at the end of starch digestion. The maltose as a transporter is responsible for the second process of regulation which is referred to as the ‘inducer exclusion’, which again is a part of the global carbon regulation bacteria. In this, the presence of the preferred carbon source which is glucose, that is responsible for the transport of inducer molecules to alternate metabolic pathways is prevented. This entire process is a result of the inhibition of the respective transport systems through a channel component of the glucose transporter, the dephosphorylated enzyme of the phosphoenolpyruvate phosphotransferase system. Next to answer the second part of the question Glucose and the other related sugars repress the process of transcription of genes that encode enzymes needed for the utilization of alternative carbon sources. Apart from that, some of these genes are also repressed by sugars such as galactose, and this process is referred to as catabolite repression.

The above-mentioned genes are not controlled by one set of regulatory proteins, but other different circuits of repression for a different set of genes.

D) The end or by-products of the combination of amylomaltase, and maltodextrin glucosidase and maltodextrin phosphorylases are glucose and alpha-glucose-1-phosphate. Hence, to channel these end products of the maltose enzymes into general metabolism, the cells depend on glucokinase for the phosphorylation of glucose to glucose-6-phosphate for the transformation of alpha-glucose-1-phosphate to glucose-6-phosphate, which enters the process of glycolysis

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