What is mutation?
• Mutation is a change in the sequence of bases in DNA or RNA
• They are heritable changes in the genetic information
• Mutations drive evolution
Mutations in non-coding DNA;
• Mostly harmless
• SNPs (single nucleotide polymorphisms); it is called for a mutation when more than 1%
of population has the mutation
1
, o If it happens in the non-coding region; it is harmless
o If it happens in the coding region; you could have a change in the function of the
gene but it will still be functioning because it is polymorphism. (You can survive with
this mutation)
Classification of mutations;
1. Gene mutations (DNA mutations); arise during replication or recombination
o Base substitutions (point mutations) (synonymous)
o Deletion (nonsynonymous)
o Insertion (nonsynonymous)
2. Chromosomal mutations
• Synonymous mutations: do not alter amino acid sequence (and are sometimes silent
mutations)
• Nonsynonymous mutations: alters the amino acid sequence of a protein
Base substitutions (point mutations);
• Transition; purine is substituted with another purine/pyrimidine is substituted with
another pyrimidine
• Transversion; purine is substituted with another pyrimidine/pyrimidine is substituted
with another purine
Occurrence types of point mutations;
• Silent; change in 3rd nucleotide such that due to wobble pairing same amino acid is
specified (no effect to the protein)
• Missense; one base change causes an amino acid to change
o Conservative missense; the change is very small
o Non-conservative missense; the change is very big
2
, • Nonsense; one base change causes an amino acid to change to a stop codon
• Neutral; changes are neither beneficial nor detrimental
Deletion and insertion
• They result in frameshift
• Insertion is adding one or more nucleotides to the sequence
• Deletion is removing one or more nucleotides to the sequence
• Insertion or deletion of multiples of 3 are in-frame since they do not alter the reading
frame of the genetic code
Types of chromosomal mutations
• Variation in chromosome structure
• Variation in number of chromosomes
Types of variations in chromosome structure
• Deletion; a portion of the chromosome breaks and get lost
• Duplication; a part of the chromosome is copied and additional genetic material is
present
• Inversion; to take a part of the chromosome turn it around and put it back in
o Pericentric inversion; includes centromere
3
, o Paracentric inversion; does not include centromere
• Translocation; a piece of one chromosome breaks off and attaches to another
chromosome
• Insertion; a portion of the chromosome is inserted to another chromosome
4
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller melinabarbut. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R127,97. You're not tied to anything after your purchase.
