When referring to attenuation in regulation of the tryptophan operon it would be safe to say that when there are high levels of tryptophan available to the . the tryptophan operon is being transcribed at relatively high levels. b. translational termination is likely. c. transcriptional termination is likely. d. tryptophan is inactivating the repressor protein. e. ribosomes are stalling during translation of the attenuator region.

High levels of Tryptophan in a bacterial cell transcription termination is likely to occur

Explanation:

In a bacterial cell transcription and translation is coupled.

Tryptophan Operon consists of the these regions Promotor Operator Leader Attenuator and Structural genes.

The Leader and Regulator regulator region is divided in to the 4 strand. 1st, 2nd is complementary to each other and so can make mRNA secondary structures and so is for 3rd, 4th strand. While 2nd and 3rd is also complementary to each other. the secondary structures are like hair pin loops. These secondary structure during coupled process helps in regulation.

When tryp opron is expressed Leader and attenuator region are first transcribed and and the initial codon begun to translated to form peptide. 1st strand: Leader mRNA contain 2 individual codons for Tryptophan amino acid and attenuator region contain a series of UUU codons.

When Tryptophan level is high in a cell Ribosomes incorporate tryp amino acid and begun to move further to 2nd strand eventually facilitates the formation of 3 and 4 strand hair pin loop by this structure mRNA become heavy, gets detached from DNA and also halting the movement of RNA polymerase before the structural genes region and so termination of transcription occur.