How would transcription of the E. coli trp operon be affected by the following manipulations of the leader region of the trp mRNA? (a) Increasing the distance (number of bases) between the leaden peptide gene and sequence 2 (b) Increasing the distance between sequences 2 and 3 (c) Removing sequence 4 (d) Changing the two trp codons r peptide gene to in the his codons (e) Eliminating the ribosome-binding site for the gene that encodes the leader peptide (f) Changing several nucleotides in sequence 3 so that it can base pair with sequence 4 but not with sequence 2

Answer

The manipulations of the leader region of the trp mRNA would affect the transcription of the E. coli trp operon in various ways, including reducing the efficiency of translational coupling, reducing the efficiency of transcription termination, and disrupting the normal structure of the leader transcript. These effects could lead to reduced production of the tryptophan biosynthetic enzymes, and lower levels of tryptophan in the cell.

Q:What is transcription and the trp operon? A:Transcription is the process by which DNA is copied into RNA, and the trp operon is a group of genes involved in the production of the amino acid tryptophan in E. coli bacteria.
Q:What is the leader region of the trp mRNA? A:The leader region of the trp mRNA is the sequence of nucleotides at the beginning of the mRNA transcript, which includes several segments that are important for regulating the production of the trp operon.
Q:How would transcription of the E. coli trp operon be affected by (a) increasing the distance between the leader peptide gene and sequence 2? A:Increasing the distance between the leader peptide gene and sequence 2 would likely reduce the efficiency of translational coupling, which is the process by which the translation of the leader peptide is coupled to the translation of the structural genes in the trp operon. This could lead to reduced production of the tryptophan biosynthetic enzymes, and lower levels of tryptophan in the cell.
Q:How would transcription of the E. coli trp operon be affected by (b) increasing the distance between sequences 2 and 3? A:Increasing the distance between sequences 2 and 3 would likely have little effect on transcription or translation of the trp operon, since these sequences are not directly involved in regulating gene expression.
Q:How would transcription of the E. coli trp operon be affected by (c) removing sequence 4? A:Removing sequence 4 would likely reduce the efficiency of transcription termination at the end of the operon, leading to longer transcripts and potentially reduced production of the tryptophan biosynthetic enzymes.
Q:How would transcription of the E. coli trp operon be affected by (d) changing the two trp codons in the leader peptide gene to his codons? A:Changing the trp codons in the leader peptide gene to his codons would likely have little effect on transcription or translation of the trp operon, since the leader peptide is not directly involved in the regulation of gene expression.
Q:How would transcription of the E. coli trp operon be affected by (e) eliminating the ribosome-binding site for the gene that encodes the leader peptide? A:Eliminating the ribosome-binding site for the gene that encodes the leader peptide would likely reduce the efficiency of translational coupling, which is the process by which the translation of the leader peptide is coupled to the translation of the structural genes in the trp operon. This could lead to reduced production of the tryptophan biosynthetic enzymes, and lower levels of tryptophan in the cell.
Q:How would transcription of the E. coli trp operon be affected by (f) changing several nucleotides in sequence 3 so that it can base pair with sequence 4 but not with sequence 2? A:Changing several nucleotides in sequence 3 would likely disrupt the normal structure of the leader transcript, which could lead to reduced translational efficiency and potentially lower production of the tryptophan biosynthetic enzymes.