What does inducible mean?
: capable of being induced: such as. a : formed by a cell in response to the presence of its substrate inducible enzymes. b : activated or undergoing expression only in the presence of a particular molecule an inducible promoter.
What is inducible ischemia?
Inducible ischemia was defined as the presence of new wall motion abnormalities at peak exercise that were not present at rest. Results from the stress echocardiogram were interpreted by a single expert cardiologist (N.B.S) who was blinded to the presence of self-reported angina.
What does inducible operon mean?
A gene system, often encoding a coordinated group of enzymes involved in a catabolic pathway, is inducible if an early metabolite in the pathway causes activation, usually by interaction with and inactivation of a repressor, of transcription of the genes encoding the enzymes.
What is meant by an inducible enzyme?
An adaptive enzyme or inducible enzyme is an enzyme that is expressed only under conditions in which it is clearly of adaptive value, as opposed to a constitutive enzyme which is produced all the time. The Inducible enzyme is used for the breaking-down of things in the cell.
What is a constitutive enzyme?
Constitutive enzyme: 1) An enzyme that is synthesized continually regardless of growth conditions. Inducible enzyme: 1) An enzyme that is synthesized *only* in the presence of the substrate that acts as an inducer.
What is an operon and what does it do?
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 is a Repressible enzyme?
n. An enzyme whose production is generally continuous but can be halted if a particular substance is present in concentrations greater than normal.
What is the benefit of the repressor being constitutively produced?
What is the benefit of the repressor being constitutively produced? – The bacteria does not want to expend energy creating lactose metabolizing enzymes if lactose is not available. The repressor negatively regulates the lac operon, preventing lactose metabolizing enzymes from being transcribed.
What happens to the lac operon in the absence of lactose?
When lactose is not available, the lac repressor binds tightly to the operator, preventing transcription by RNA polymerase. However, when lactose is present, the lac repressor loses its ability to bind DNA. When lactose is absent, the lac repressor binds tightly to the operator.
Is lac operon positive or negative?
The lac operon is a negatively controlled inducible operon, where the inducer molecule is allolactose. In negative repressible operons, transcription of the operon normally takes place. Repressor proteins are produced by a regulator gene, but they are unable to bind to the operator in their normal conformation.
Which is an example of negative regulator Mcq?
CRP-cAMP is a negative regulatory element while lac repressor is a positive regulatory element. Both CRP-cAMP and lac repressors are negative regulatory elements.
Why is the lac operon negative?
Explanation: The lac operon exhibits both systems. It is a negative control system because expression is typically blocked by an active repressor (the lac repressor) that turns off transcription. The lac repressor binds to the operator region and negatively controls (prevents) transcription.
Which is an example of negative regulation?
Repressor binding blocks RNA polymerase from binding with the promoter, thereby leading to repression of operon gene expression. A classic example of negative repressible regulation of gene expression involves the trp operon, which is regulated by a negative feedback loop.
What does negative regulation mean?
Negative Regulation. The binding of a specific protein (repressor) inhibits transcription from occurring. DNA bound repressors often act to prevent RNA polymerase from binding to the promoter, or by blocking the movement of RNA polymerase.
What is the difference between a negative regulator and a positive regulator?
In negative regulation a repressor protein binds to an operator to prevent a gene from being expressed. In positive regulation a transcription factor is required to bind at the promoter in order to enable RNA polymerase to initiate transcription.
What is the negative control?
Negative controls are particular samples included in the experiment that are treated the same as all the other samples but are not expected to change due to any variable in the experiment. The proper selection and use of controls ensures that experimental results are valid and saves valuable time.
What is the purpose of the negative control?
A negative control is a group in an experiment that does not receive any type of treatment and, therefore, should not show any change during the experiment. It is used to control unknown variables during the experiment and to give the scientist something to compare with the test group.
Why are negative controls used?
On the other hand, a negative control is an experiment in which the microbiologist knows that there will be a negative outcome. This helps the analyst compare the result to a new experiment against an already results that are already known. Negative controls are always used during microbiology testing.
Why do experiments have negative and positive controls?
For scientists, positive controls are very helpful because it allows us to be sure that our experimental set-up is working properly. For example, suppose we want to test how well a new drug works and we have designed a laboratory test to do this. The “negative-control” sets what we sometimes call the “baseline”.
Are controls always necessary?
A true experiment (a.k.a. a controlled experiment) always includes at least one control group that doesn’t receive the experimental treatment. Without a control group, it’s harder to be certain that the outcome was caused by the experimental treatment and not by other variables.
What is a positive vs negative control?
A negative control is a control group in an experiment that uses a treatment that isn’t expected to produce results. A positive control is a control group in an experiment that uses a treatment that is known to produce results.
Why is water a negative control?
Water is commonly used as a negative control in chemical tests, especially distilled water. The distilled water is devoid of any minerals or salts, unlike regular water (or tap water) and hence is not likely to participate in any chemical reaction.
Why does distilled water not boil?
Boiling point elevation occurs when there are dissolved minerals in the water. Distilled water usually has some of the mineral impurities removed and so you would expect it to boil at exactly 100 degrees C. Therefore, normal tap water should boil at a higher temperature than distilled water.
Is water a positive or negative charge?
There is no overall charge to a water molecule, but there is a slight positive charge on each hydrogen atom and a slight negative charge on the oxygen atom. Because of these charges, the slightly positive hydrogen atoms repel each other and form the unique shape seen in [link].
Can you drink distilled water?
Distilled water is safe to drink. But you’ll probably find it flat or bland. That’s because it’s stripped of important minerals like calcium, sodium, and magnesium that give tap water its familiar flavor. What’s left is just hydrogen and oxygen and nothing else.