In genetics, attenuation is a proposed mechanism of control in some bacterial operons which results in premature termination of transcription and is based on the fact that, in bacteria, transcription and translation proceed simultaneously.
Where does attenuation occur?
Classically, attenuation occurs when the transcribed RNA upstream of an operon has the ability to fold into two mutually-exclusive RNA-fold structures, one which is termed an antiterminator and the other a terminator. If the terminator hairpin loop is allowed to fold, transcription is ultimately halted.
What is the role of attenuation?
Attenuation is an important factor limiting the transmission of a digital signal across large distances. Thus, much research has gone into both limiting the attenuation and maximizing the amplification of the optical signal.
What is attenuation control of transcription?
Transcriptional attenuation is a regulatory mechanism that causes premature termination of transcription under certain conditions, thereby preventing the expression of the mRNA required for expression of the corresponding gene products.
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 attenuator mean?
Definition of attenuator
: a device for attenuating especially : one for reducing the amplitude of an electrical signal without appreciable distortion.
What causes attenuation in E. coli?
When levels of tryptophan are high, attenuation causes RNA polymerase to stop prematurely when it’s transcribing the trp operon.
How do you calculate attenuation?
The amount of attenuation in a given network is determined by the ratio of: Output/Input. For example, if the input voltage to a circuit is 1 volt (1V) and the output voltage is 1 milli-volt (1mV) then the amount of attenuation is 1mV/1V which is equal to 0.001 or a reduction of 1,000th.
What are the two types of attenuation?
The different types of attenuation are deliberate, automatic, and environmental. Deliberate type mainly occurs where the volume control is required to reduce the level of sound on electronic devices.
What is the difference between attenuation and absorption?
In Physics, the main difference between attenuation and absorption is that attenuation is the gradual reduction in the intensity of a signal or a beam of waves which is propagating through a material medium whereas the absorption is the way in which the energy of a photon is taken up by matter.
What causes attenuation?
Attenuation is caused by passive media components such as cables, cable splices, and connectors. Although attenuation is significantly lower for optical fiber than for other media, it still occurs in both multimode and single-mode transmission.
How does attenuation regulate trp operon?
When tryptophan is low, RNA polymerase (blue) reads through the attenuator and genes are transcribed. Attenuation of the trp operon of E. coli. When tryptophan is high, the attenuator causes premature termination of transcription, so the genes that produce more tryptophan are not transcribed.
What is Monocistronic and Polycistronic?
The monocistronic transcription unit contains a structural gene coding for only one polypeptide (mostly in eukaryotic cells), whereas the polycistronic transcription unit contains structural genes coding for more than one polypeptides (mostly in prokaryotic cells).
Does lac operon have attenuation?
Attenuation depends on an interaction between transcription and translation in a “leader sequence” at the beginning of the operon. Attenuation is common in other operons that synthesize amino acids.
What is lac operon in biology?
The lac operon is an operon, or group of genes with a single promoter (transcribed as a single mRNA). The genes in the operon encode proteins that allow the bacteria to use lactose as an energy source.
What is immunology attenuation?
function in immunization
Weakened, or attenuated, vaccines consist of microorganisms that have lost the ability to cause serious illness but retain the ability to stimulate immunity. They may produce a mild or subclinical form of the disease.
