Regulation of the trp Operon

The video tutorial explains the regulation of the trp operon in E. coli, focusing on the concept of attenuation. It describes how the presence or absence of tryptophan affects the transcription of genes responsible for its biosynthesis. The trp operon consists of regulatory and structural genes, with transcription regulated by the formation of stem-loop structures in the leader mRNA. The video details how the ribosome's position and tryptophan levels influence these structures, ultimately controlling gene expression.

What happens to the operon when amino acids are present in the nutritional medium?

• The operon is activated to produce enzymes.

• The operon produces more amino acids.

• The operon is unaffected by amino acids.

• The operon is repressed, stopping enzyme synthesis.

Which of the following is a component of the trp operon?

• Promoter/operator region

• Mitochondrial DNA

• Ribosomal RNA

• Lipid bilayer

What is the function of the polycistronic mRNA in the trp operon?

• It encodes multiple polypeptides for tryptophan production.

• It regulates the cell cycle.

• It transports tryptophan across the cell membrane.

• It degrades excess tryptophan.

What is the role of the leader mRNA in the trp operon?

• It encodes for structural proteins.

• It forms stem-loop structures for regulation.

• It transports amino acids.

• It degrades unnecessary proteins.

What signal is produced when regions 2 and 3 pair in the leader mRNA?

• A start signal

• An antitermination signal

• A termination signal

• A degradation signal

Why is the position of the ribosome on the leader mRNA important?

• It regulates transcription by forming specific structures.

• It influences the folding of proteins.

• It determines the speed of translation.

• It affects the stability of mRNA.

What happens when the ribosome reaches the two Trp codons and tryptophan is scarce?

• The ribosome continues translation.

• The ribosome stops, preventing leader peptide completion.

• The ribosome synthesizes a different protein.

• The ribosome detaches from the mRNA.

What is the result of region 3 pairing with region 4 in the leader mRNA?

• The ribosome stalls.

• A termination signal is generated.

• A new operon is activated.

• Transcription continues.

How does the concentration of Trp-tRNA affect the trp operon?

• It changes the cell's membrane structure.

• It affects the cell's energy production.

• It signals whether transcription should continue or terminate.

• It determines the rate of DNA replication.

What happens if Trp and Trp-tRNA are abundant in the cell?

• A long mRNA transcript is synthesized.

• Transcription is terminated, stopping enzyme production.

• The operon is activated to produce more tryptophan.

• The cell enters a dormant state.