All of the following are true of operons EXCEPT: A. they contain several genes t

Question

All of the following are true of operons EXCEPT: A. they contain several genes that are transcribed together B. each gene in the operon has a start codon and a stop codon C. a separate mRNA is made for each gene In the operon D. Each gene in an operon would be translated by a separate ribosome A bacterium is in an environment that is rich in tryptophan. Which of the following would happen? A. The tryptophan would bind to the trp repressor. The result would be that the repressor can no longer bind the trp operator. B. The tryptophan would bind to the trp repressor. The result would be that RNA polymerse can't transcribe the operon C. The tryptophan would bind to the trp repressor. The result would be that the trp operon becomes active. D. The tryptophan would bind to the trp repressor. The result would be that the cell would make enzymes that break down tryptophan.

Explanation / Answer

Ans 1(C) a separate mRNA is made for each gene in the operon.

A single mRNA is transcibed in operon which is translated into different proteins.

Ans2. (A,B) The operon is regulated so that when tryptophan is present in the environment, the genes for tryptophan synthesis are not expressed.

The tryptophan (Trp) operon is inhibited by tryptophan. Within the operon's regulatory sequence, the operator is blocked by the repressor protein in the presence of tryptophan (thereby preventing transcription).

Trp bind to inactive repressor protein-------> Active repressor bind to operator---------> Inhibit function of RNA polymerase---------> No trp synthesis

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