What is the lac operon used for?
The lac, or lactose, operon is found in E. coli and some other enteric bacteria. This operon contains genes coding for proteins in charge of transporting lactose into the cytosol and digesting it into glucose. This glucose is then used to make energy.
What are the three important features of the lac operon quizlet?
The lac operon contains an operator, promoter, and structural genes that are transcribed together and are under the control of the catabolite activator protein (CAP) or repressor….
- transformation.
- transduction.
- bacterial conjugation.
What is P in lac operon?
In addition to the three protein-coding genes, the lac operon contains short DNA sequences that do not encode proteins, but are instead binding sites for proteins involved in transcriptional regulation of the operon. In the lac operon, these sequences are called P (promoter), O (operator), and CBS (CAP-binding site).
What are the two types of operons?
Operons are of two types, inducible and repressible.
What type of proteins does the lac operon produce?
The lac operon consists of three structural genes: lacZ, which codes for β-galactosidase, which acts to cleave lactose into galactose and glucose; lacY, which codes for lac permease, which is a transmembrane protein necessary for lactose uptake; and lacA, which codes for a transacetylase that transfers an acetyl group …
What does operon mean?
Operon: A set of genes transcribed under the control of an operator gene. More specifically, an operon is a segment of DNA containing adjacent genes including structural genes, an operator gene, and a regulatory gene. An operon is thus a functional unit of transcription and genetic regulation.
What is operon and its function?
Operon, genetic regulatory system found in bacteria and their viruses in which genes coding for functionally related proteins are clustered along the DNA. This feature allows protein synthesis to be controlled coordinately in response to the needs of the cell.
What does an operon consist of?
An operon consists of an operator, promoter, regulator, and structural genes. The regulator gene codes for a repressor protein that binds to the operator, obstructing the promoter (thus, transcription) of the structural genes. The regulator does not have to be adjacent to other genes in the operon.
Why are there no operons in eukaryotes?
When an operon is transcribed, all of the genes on the operon are on the same mRNA. Operons occur in prokaryotes, but not eukaryotes. In eukaryotes, each gene is made on individual mRNAs and each gene has its own promoter. Cells can’t afford to waste energy making genes if they don’t need them.
Why are there no eukaryotes?
We lack operons because gene regulation is so complex that you could not possibly fit genes that code for regulation points close enough to the genes they regulate. Operons depend upon having the structural gene closely downstream, while Eukaryotic genes do not have this luxury due to these complex control mechanisms.
Why is attenuation not found in eukaryotes?
1). There is no coupling of transcription and translation in eukaryotic cells as in bacterial cells. Consequently, ribosome movement and arrest cannot modulate attenuation.
What is the process of attenuation?
Attenuation is a regulatory mechanism used in bacterial operons to ensure proper transcription and translation. In bacteria, transcription and translation are capable of proceeding simultaneously. The process of attenuation involves the presence of a stop signal that indicates premature termination.
How is attenuation regulated?
More trp operon regulation: Attenuation 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.
What does the medical term attenuation mean?
Medical Definition of attenuation : a decrease in the pathogenicity or vitality of a microorganism or in the severity of a disease. attenuation.
What is attenuation and why is it important?
Attenuation is the loss of signal strength in networking cables or connections. This typically is measured in decibels (dB) or voltage and can occur due to a variety of factors. It may cause signals to become distorted or indiscernible.
What can cause attenuation?
What Causes It?
- Noise. Extra noise on networks, like radio frequencies, electrical currents, and wire leakage, may interfere with the signal and cause attenuation.
- Physical surroundings. Physical surroundings like temperature, wall barriers, and improper wire installation may distort the transmission.
- Travel distance.
What does attenuation mean on CT scan?
The density of the tissue is in proportion to the attenuation of the x-rays which pass through. Tissues like air and water have little attenuation and are displayed as low densities (dark), whereas bone has high attenuation and is displayed as high density (bright) on CT.
What does low attenuation mean on CT scan?
Attenuation is a feature of CT, and low attenuation means that a particular area is less intense than the surrounding. All of the malignant nodules confirmed by biopsy have low attenuation, with the exception of two which have a mixture of high and low attenuation.
What does attenuation mean in radiology?
Attenuation is the reduction of the intensity of an x-ray beam as it traverses matter. The reduction may be caused by absorption or by deflection (scatter) of photons from the beam and can be affected by different factors such as beam energy and atomic number of the absorber.
What does fluid look like on CT?
Fluid on CT is relatively hypodense (dark). It can be compared to fluid in the gallbladder or stomach. Dense fluid may suggest hemoperitoneum, especially in the context of trauma.
Does ascites go away on its own?
Stopping all alcohol intake, maintaining a healthy weight, exercising, not smoking, and limiting salt intake can help prevent cirrhosis or cancer that may lead to ascites. Ascites can’t be cured but lifestyle changes and treatments may decrease complications.
Is free fluid in abdomen normal?
Ascites occurs when fluid accumulates in the abdomen. This buildup occurs between two membrane layers that together make up the peritoneum, a smooth sac that contains the body’s organs. It is usual to have a small amount of fluid in the peritoneum cavity.
How can you tell if its a CT or MRI?
A typical CT scan lasts 10 minutes whereas MRIs can take up to an hour or longer. Images: MRIs will produce sharper, more detailed results, especially of soft tissues and behind bones, which may block views on CT scans.
What has more radiation CT scan or MRI?
CT scans use radiation (X-rays), and MRIs do not. MRIs provide more detailed information about the inner organs (soft tissues) such as the brain, skeletal system, reproductive system and other organ systems than is provided by a CT scan. CT scans are quick, painless, and noninvasive.
What can an MRI detect that a CT scan Cannot?
Where MRI really excels is showing certain diseases that a CT scan cannot detect. Some cancers, such as prostate cancer, uterine cancer, and certain liver cancers, are pretty much invisible or very hard to detect on a CT scan. Metastases to the bone and brain also show up better on an MRI.