Is attenuation possible in eukaryotes?

Is attenuation possible in eukaryotes?

Prokaryotes commonly use attenuation as a mechanism to control gene expression, but eukaryotes do not.

What is Antitermination in molecular biology?

Antitermination is the prokaryotic cell’s aid to fix premature termination of RNA synthesis during the transcription of RNA. It occurs when the RNA polymerase ignores the termination signal and continues elongating its transcript until a second signal is reached.

Why does attenuation not occur eukaryotes?

So eukaryotic cells does not undergo attenuation because the process of the transcription and translation occurs at different time and location time and location.

What is Antitermination trp operon?

Antitermination by a stalled ribosome In the E. coli trp operon, a small leader peptide contains two tandem Trp codons (FIG. 3b). When the levels of Trp and charged tRNATrp are high, the ribosome completes the synthesis of the leader peptide, the terminator forms and RNAP is released.

Why is attenuation possible for prokaryotes and not eukaryotes?

Attenuation is possible because the genetic material of prokaryotes in in the cell’s cytoplasm with its ribosomes. In prokaryotes, it is possible for ribosomes to begin translating the mRNA while RNA polymerase is still transcribing the DNA sequence, allowing translation to have an effect on transcription.

Why can’t eukaryotic cells regulate transcription by attenuation?

(In eukaryotes, there is no exact equivalent of attenuation, because transcription occurs in the nucleus and translation occurs in the cytoplasm, making this sort of coordinated effect impossible.)

What happens when trp is present?

When tryptophan is present in the cell, two tryptophan molecules bind to the trp repressor, which changes shape to bind to the trp operator. Binding of the tryptophan–repressor complex at the operator physically prevents the RNA polymerase from binding and transcribing the downstream genes.

What is the function of the trp operon?

Tryptophan (Trp) Operon. The tryptophan operon is responsible for the production of the amino acid tryptophan, whose synthesis occurs in five steps, each requiring a particular enzyme. In E. coli, these enzymes are translated from a single polycistronic mRNA.

How attenuation regulates protein synthesis in prokaryotic cells?

Attenuation occurs by a mechanism by which rapid translation of the nascent transcript causes the termination of transcription. As the transcript is being produced, if ribosomes attach and rapidly translate the transcript, a secondary structure is generated in the mRNA that is a termination signal for RNA polymerase.

How is transcription regulated in eukaryotes?

As in bacteria, transcription in eukaryotic cells is controlled by proteins that bind to specific regulatory sequences and modulate the activity of RNA polymerase.

What is the purpose of a trp operon?

Is trp usually on or off?

The trp operon is an example of a repressible system, meaning that the operon is automatically turned on unless a repressor becomes active and turns it off.

What is the difference between lac operon and trp operon?

What is the difference between Lac operon and Trp operon? Lac operon is involved with the catabolic process of a sugar, but Trp operon is involved in the anabolic process of an amino acid. Lac operon gets activated in the presence of lactose, but Trp operon gets deactivated in the presence of tryptophan.

Why does attenuation only happen in prokaryotes?

Attenuation is made possible by the fact that in prokaryotes (which have no nucleus), the ribosomes begin translating the mRNA while RNA polymerase is still transcribing the DNA sequence. This allows the process of translation to directly affect transcription of the operon.

What is the attenuation process?

The process of attenuation involves the presence of a stop signal that indicates premature termination. The stop signal, referred to as the attenuator, prevents the proper function of the ribosomal complex, stopping the process.

What does transcription in eukaryotes require?

Like prokaryotic cells, the transcription of genes in eukaryotes requires the action of an RNA polymerase to bind to a DNA sequence upstream of a gene in order to initiate transcription.