Is 5-bromouracil carcinogenic?

Laboratory chemical used as a mutagen in many mutagenesis experiments. 5-bromouracil is a mutagen (causes mutations) and a carcinogen.

What is 5-bromouracil an example of?

Examples of base analogues include 5-bromouracil, 2-aminopurine, 6-mercaptopurine, and acycloguanosine (Figure 21.9). Since 5-bromouracil can pair with either adenine or guanine, it also affects base pairing during DNA replication, which leads to mutations.

How do base analogs cause mutations?

Once in place, these analogs have pairing properties unlike those of the normal bases; thus, they can produce mutations by causing incorrect nucleotides to be inserted opposite them in replication.

Which nucleobase pairs best with 5-bromouracil?

5-Bromouracil, an analog of thymine, normally pairs with adenine.

What is the purpose of the Ames test?

The Ames test is used world-wide as an initial screen to determine the mutagenic potential of new chemicals and drugs. The test is also used for submission of data to regulatory agencies for registration or acceptance of many chemicals, including drugs and biocides.

How is Ames test performed?

The Ames Test combines a bacterial revertant mutation assay with a simulation of mammalian metabolism to produce a highly sensitive test for mutagenic chemicals in the environment. A rat liver homogenate is prepared to produce a metabolically active extract (S9).

What kind mutation can 5 Bromouracil induce?

5-Bromouracil (BrU) is a base analogue of thymine (T) which can be incorporated into DNA. It is a well-known mutagen, causing transition mutations by mispairing with guanine (G) rather than pairing with adenine (A) during replication.

Which base is generated by the deamination of 5 methylcytosine?

While spontaneous deamination of cytosine forms uracil, which is recognized and removed by DNA repair enzymes, deamination of 5-methylcytosine forms thymine. This conversion of a DNA base from cytosine (C) to thymine (T) can result in a transition mutation.

How does an intercalating agent introduce a mutation?

Intercalating agents are another type of chemical mutagen. They tend to be flat, planar molecules like benzo[a]pyrene, a component of wood and tobacco smoke, and induce mutations by inserting between the stacked bases at the center of the DNA helix.

What are base analogs examples?

Examples of base analogues include 5-bromouracil, 2-aminopurine, 6-mercaptopurine, and acycloguanosine (Figure 21.9). Since 5-bromouracil can pair with either adenine or guanine, it also affects base pairing during DNA replication, which leads to mutations.

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What is base analog mutation?

Base analogs are molecules which have a very similar structure to one of the four nitrogenous bases which are used in DNA (adenine, guanine, cytosine or thymine). … This means if used as a template strand during replication, they will pair with a different base and cause a base change mutation.

Are base analogs mutagens?

Base analogs are derivatives of the normal DNA bases, which may mimic to varying extents the properties of the normal bases. As such, they have the ability to interfere with normal nucleotide metabolism and exert a variety of toxic and mutagenic effects.

What happens when adenine pairs with cytosine?

Guanine always bonds with cytosine, which makes them a pair of complementary bases. Adenine always bonds with thymine, making them DNA’s other pair of complementary bases. These pairs form the “rungs” of the DNA ladder.

What does uracil pair with?

adenine During the synthesis of an RNA strand from a DNA template (transcription), uracil pairs only with adenine, and guanine pairs only with cytosine.

What happens if a nitrogen base is paired wrong?

When there is a mistake in the copying of the genetic message that is permanent, a mutation has occurred. … Two of the bases in DNA (Cytosine and Thymine) are the most vulnerable, and when this happens, they may pair with each other or themselves and the message is changed.

What is Ames toxicity?

Models and Methods for In Vitro Toxicity Ames test devised by a scientist “Bruce Ames” is used to assess the potential carcinogenic effect of chemicals by using the bacterial strain Salmonella typhimurium. This strain is mutant for the biosynthesis of histidine amino acid.

Which organism is used in Ames test?

Test organism: Ames test uses several strains of bacteria (Salmonella, E.coli) that carry mutation. Eg A particular strain of Salmonella Typhimurium carry mutation in gene that encodes histidine.

Which organism is normally used in the Ames test?

The Ames test uses several strains of the bacterium Salmonella typhimurium that carry mutations in genes involved in histidine synthesis. These strains are auxotrophic mutants, i.e. they require histidine for growth, but cannot produce it.

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Is Ames test in vivo?

bacterial point mutation test (the Ames test), a chromosomal aberrations test in mammalian cells in vitro, and an in vivo (intact animals) test.

What is the main advantage of the Ames test for mutation detection?

The Ames test has several key advantages: It is an easy and inexpensive bacterial assay for determining the mutagenicity of any chemical. Results are robust, and the Ames test can detect suitable mutants in large populations of bacteria with high sensitivity. It does not require any special equipment or instrumentation.

What is S9 in Ames test?

Applications. The S9 fraction has been used in conjunction with the Ames test to assess the mutagenic potential of chemical compounds. Chemical substances sometimes require metabolic activation in order to become mutagenic. … The S9 fraction has also been used to assess the metabolic stability of candidate drugs.

What is the detection technique of Auxotrophs Mcq?

What is the detection technique of auxotrophs? Explanation: Auxotrophs is a conditional lethal mutation in which mutants need essential metabolites for proper growth. 8. Name the type of mutation in which the cause of mutation is not known?

What are tautomeric shifts?

The spontaneous isomerization of a nitrogen base to an alternative hydrogen-bonding form, possibly resulting in a mutation. Reversible shifts of proton position in a molecule. bases in nucleic acids shift between keto and enol forms or between amino and imino forms.

What is the role of base analog in mutation?

Base analog mutagens are chemicals that mimic bases to such an extent that they can be incorporated into DNA in place of one of the normal bases but in doing so lead to an increase in the rate of mutation. To be mutagenic, a base analog must mispair more frequently than the normal base it replaced.

What causes mutation of 5-methylcytosine to thymine?

The DNA of many bacterial and eukaryotic species contains 5-methylcytosine (5meC) in addition to cytosine. Deamination of 5meC produces thymine, which is not recognized by uracil glycosylase and consequently can result in C → T mutations.

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Why is 5-methylcytosine a hotspot for mutation?

Spontaneous deamination of 5-methylcytosine produces thymine which, if not corrected, can result in a transition mutation. 5-Methylcytosines in the lacI gene are hotspots for spontaneous C to T mutations. dcm is linked to vsr, a gene required for very short patch (VSP) repair.

Which enzyme catalyzes the formation of 5-methylcytosine?

Methylation of cytosine at C5 position by DNA methyltransferase enzyme (DNMT)(1) produces 5-methylcytosine (5mC), the “fifth base” that has long been known to play a central role in gene repression via epigenetic regulation.

What does an intercalating agent do?

A substance that inserts itself into the DNA structure of a cell and binds to the DNA. … In cancer treatment, DNA intercalating agents may kill cancer cells by damaging their DNA and stopping them from dividing.

How does an intercalating agent such as ethidium bromide cause mutations?

How does an intercalating agent such as ethidium bromide cause mutations? … These intercalating agents are flat molecules that can slip between base pairs in the double helix, slightly unwinding the helix and hence increasing the distance between adjacent pairs. This way these molecules cause the mutation.

What causes Depurination?

In cells, one of the main causes of depurination is the presence of endogenous metabolites undergoing chemical reactions. … Hydrolytic depurination is one of the principal forms of damage to ancient DNA in fossil or subfossil material, since the base remains unrepaired.

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