What does attenuation mean in genetics?
premature termination of transcription
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.
How does attenuation regulate gene expression?
Like regulation by the trp repressor, attenuation is a mechanism for reducing expression of the trp operon when levels of tryptophan are high. However, rather than blocking initiation of transcription, attenuation prevents completion of transcription.
How does attenuation work biology?
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 attenuation mean in microbiology?
The response of the synthesis of bacterial mRNA to the nutritional state of the organism, e.g. the decrease in transcription of the trp operon in the presence of tryptophan, which is due to the incomplete transcription of a leader mRNA sequence coded for by the attenuator sequence.
What does attenuate mean in medical terms?
Listen to pronunciation. (uh-TEN-yoo-way-ted) Weakened or thinned. Attenuated strains of disease-causing bacteria and viruses are often used as vaccines.
What is attenuation in ultrasound?
The amplitude and intensity of ultrasound waves decrease as they travel through tissue, a phenomenon known as attenuation. Given a fixed propagation distance, attenuation affects high frequency ultrasound waves to a greater degree than lower frequency waves.
What causes attenuation?
Attenuation is the reduction in power of the light signal as it is transmitted. Attenuation is caused by passive media components such as cables, cable splices, and connectors.
What does attenuation mean in ultrasound?
What causes ultrasound attenuation?
Attenuation of ultrasound waves traversing a medium is not only a result of absorption and scattering within a given tissue, but also of coherent scattering, including diffraction, refraction, and reflection of the acoustic wave at tissue boundaries.
What is attenuation and how was it discovered?
Attenuation was first observed by Charles Yanofsky in the trp operon of E. coli. The first observation was linked to two separate scientific facts. Mutations which knocked out the trp R (repressor) gene still showed some regulation of the trp operon (these mutants were not fully induced/repressed by tryptophan).
What does attenuator mean?
Attenuator (genetics) Attenuation (in genetics) 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. Attenuation involves a provisional stop signal (attenuator),…
What is the function of the attenuator in transcription?
Depending on the metabolic conditions, the attenuator either stops transcription at that point or allows read-through to the structural gene part of the mRNA and synthesis of the appropriate protein. Attenuation is a regulatory feature found throughout Archaea and Bacteria causing premature termination of transcription.
Where is the attenuator sequence located on the mRNA?
The attenuator sequence, which is located between the mRNA leader sequence (5′ UTR) and trp operon gene sequence, contains four domains, where domain 3 can pair with domain 2 or domain 4. The attenuator sequence at domain 1 contains instruction for peptide synthesis that requires tryptophans.