PPT On Mutations
Mutations Presentation Transcript:1. MUTATIONS
Mutation are heritable changes in the genetic material. They result from small changes in the genetic material (single gene mutations), rearrangements in chromosome structure (chromosome mutations), or changes in chromosome number( genome mutations).
2. MUTATIONS CAN OCCUR IN TWO WAYS:
Spontaneous mutation Induced mutations
3. SPONTANEOUS MUTATIONS
Spontaneous mutations can arise from transition, transversion and frameshifts), from dNA lesions (replication errors (apurinic sites, apyrimidinic sites, oxidation ), and from insertions.
4. TRANSITION MUTATIONS
The tautomeric shifts changes the hydrogen bonding characteristics of the bases allowing purine for purine, pyrimidine for pyrimidine substitution that eventually leads to a stable alteration of nucleotide sequences. Such alterations are known as transition mutation.
5. TRANSVERSION MUTATION
In transversion mutations, a purine is substituted for a pyrimidine, or a pyrimidine for purine. These mutations are rare due to steric problems of pairing purine with purine and pyrimidine with pyrimidine.
6. INDUCED MUTATIONS
Induced mutation are caused by mutagens. Mutations may result from the incorporation of base analogs, specific misparing due to alteration of a base, the presence of intercalating agents, and a by pass of replication because of severe damage.
7. BASE ANALOGS
Base analogs are structurally similar to normal nitrogenous bases and can be incorporated into the growing polynucleotide chain during replication. Once in place, these compounds typically exhibit base pairing properties different from the bases they replace and eventually causes stable mutations.
8. SPECIFIC MISPAIRING
Specific mispairing is caused when a mutagen changes a base structure and therefore alters its base pairing characteristics. Some mutagens in this category are fairly selective; they preferentially react with some bases and produce a specific kind of DNA damage.
9. INTERCALATING AGENTS
Intercalating agents distort DNA to induce single nucleotide pair insertion and deletion. These mutagens are planar and insert themselves (intercalate) between the stacked bases of the helix.
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