What does 5-bromouracil do to DNA?
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.
When the thymine analog 5-bromouracil incorporated into DNA normally occupied by thymine what type of mutation can occur?
Base analogs such as 5-bromouracil and 2-aminopurine can be incorporated into DNA and are even more likely than normal nucleic acid bases to form transient tautomers that lead to transition mutations. 5-Bromouracil, an analog of thymine, normally pairs with adenine.
Is 5-bromouracil an alkylating agent?
These mutagens are, in general, large, planar aromatic molecules that can intercalate into the DNA. These molecules are highly fluorescent and are commonly used to stain DNA in agarose gels, due to their intercalating and fluorescent properties. The third group of mutagens are the direct alkylating agents.
What happens if guanine pairs with thymine?
The only pairs that can create hydrogen bonds in that space are adenine with thymine and cytosine with guanine. A and T form two hydrogen bonds while C and G form three. It’s these hydrogen bonds that join the two strands and stabilize the molecule, which allows it to form the ladder-like double helix.
Why does 5 Bromouracil frequently pair with guanine?
5-BU is a derivative of uracil, and its 5 position of the pyrimidine ring is halogenated. If 5-BU is incorporated into DNA in place of thymine, the tautomeric shift will occur, and the 5-BU will base pair with guanine.
What is another name for thymine?
Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. In RNA, thymine is replaced by the nucleobase uracil.
Why is 5-bromouracil more reactive than thymine?
The base analog 5-bromouracil (BU) is efficiently incorporated into DNA in place of thymine (T). It is mutagenic because BU is more often in the enol form than is T, and in this form it can base pair with guanine (G). (BU is also more reactive to ultraviolet light than T, and this may also increase the level of mutation.)
How does 5 bromouracil affect base pairing during DNA replication?
Since 5-bromouracil can pair with either adenine or guanine, it also affects base pairing during DNA replication, which leads to mutations.
Which is formed by bromination in place of thymine?
Uracil is halogenated in the carbon-5 position to give 5-bromouracil, 5-chlorouracil, and 5-iodouracil which can be incorporated into DNA in the place of thymine. 5-bromouracil (5-BU) bromine is formed by bromination at the carbon-5 position of uracil. The resulting structure of 5-bromouracil is similar to thymine but thymine has CH3 group at C5 .
How is 5-bu similar to thymine in structure?
Fig. 2.23. Structural similarity. 5-BU is structurally similar to thymine, therefore it is considered a thymine analog and base-pairs normally with adenine. It is rarely present in its enol form, in which it base pairs with guanine.