4.10.2007 - 4.10.2007 Mutagens what are the agents that...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
4.10.2007 Mutagens: what are the agents that induce changes in DNA, UV radiation or a chemical There are so many chemicals that can do this so we will go through a few categories with a few examples per category Chemical Mutagens Deaminating agents o Act upon an Amine group such as the one in cytosine o Example of a deaminating agent is nitrous acid It converts an amine to a carbonyl which converts cytosine into a uracil This is uracil bound to deoxyribose sugar though, so it is Uracil in DNA (shouldn’t be here) LESION: name of it is deoxyuradine Uracil base pairs with adenine while the new strand should have Guanine on the new strand (because G pairs with C) this is a TRANSITION o Book much more complex on what a deaminating agent will do, because C is not the only base with exocyclic amine group nonetheless this example tells you everything you need to know: shows that deaminating agent such as nitrous acid will covert an exocyclic amino group to a carbonyl and it will do this on whatever base has the exocylic amine group, also shows that it is a lesion (it is a rare base because U is rare in DNA, a rare base attached to deoxyribose). This is also true with other bases that are deaminated but the names of the other bases are not ones that we have talked about. And if you looked at the other bases you would see the rare base would base pair differently to cause a transition at replication. Remembering how this example works you know how it works for the other bases as well, just this is the only one you need to know specific names. Where do you run into nitrous acid? Chemistry lab…another reminder that the warnings you get in the syllabus or from a TA in lab are serious. It is not just a general training that we would like you to be careful. We are warning of you that you are in danger if you don’t treat this stuff with respect. Mutagens are used in the lab to create mutations because geneticists want to see what happens when DNA is mutated. This is number one mutagen used and it is very effective. Outside Chemistry lab nitrous acid is a part of air pollution in general. Alkylating agents o Causes an alkyl group to be added onto DNA o Alkyl group had carbons and hydrogens can be as small as a methyl group or as large as anything o First item on the handout is nitrosamine, wouldn’t be a problem except that it is one of so many things that come into your body that it must metabolize to try to get rid of it. Liver enzymes will try to metabolize whatever sits around that is not a natural product. Liver is trying to make it easier to excrete. That usually works but not in this case. o The liver ends up breaking the bond between a methyl group and a nitrogen o The dot on the methyl is an unpaird electron, a methyl radical, highly reactive, can attach to a number of things but its favorite target is guanine o Can attach to guanine in one of two places with different results. The methyl radical might attach to the
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/07/2008 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas.

Page1 / 5

4.10.2007 - 4.10.2007 Mutagens what are the agents that...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online