The lacI gene regulates transcription of the structural genes by producing a repressor molecule that is...

The lacI gene regulates transcription of the structural genes by producing a repressor molecule that is allosteric, meaning that

		it interacts irreversibly with a gene, causing both a conformational change in three-dimensional shape and a change in chemical activity of the enzyme
		it interacts reversibly with a gene, causing both a conformational change in three-dimensional shape and a change the protein it codes for
		it interacts irreversibly with another molecule, causing both a conformational change in three-dimensional shape and a change in chemical activity
		it can break down polysaccharides into small subunits.
		it interacts reversibly with another molecule, causing both a conformational change in three-dimensional shape and a change in chemical activity

Expert Solution

The lacI gene regulates transcription of the structural genes by producing a repressor molecule that is allosteric, meaning that

it interacts reversibly with another molecule, causing both a conformational change in three-dimensional shape and a change in chemical activity

Explaination:

Allosteric regulation of a protein is the regulation where a regulatory ligand bind with protein at place other than its active site, causing the change in conformation and activity of that protein.
lacI repressor regulates the transcription of Lac Operon.
lacI repressor bind to the Operator region of the gene thus NOT allowing RNA polynerase to bind with gene. Therefore transcription of gene is inhibitted
When lactose is present, lactose bind to lacI repressor. This cause the change in three-dimensional shape of repressor. So that it can NOT bind to the opertaor. These means the activity of lacI is changed/altered.
Therefore there is change in three-dimensional shape and activity of protein lacI after binding of a ligand as lactose. So this is an example of allosteric regulation
BInding between lacI and lactose is revesible, because in absence of lactose, lacI bind again to operator, supressing the transcription.

gladiator answered 2 years ago

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