Mutations Flashcards
What are mutations?
Mutations are changes in the DNA that can result in no protein or an altered protein being synthesised.
What are single gene mutations?
Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides.
Name the three types of nucleotide substitutions.
Missense, nonsense and splice-site mutations.
Describe missense mutations.
Missense mutations result in one amino acid being changed for another. This may result in a non-functional protein or have little effect on the protein.
Describe nonsense mutations.
Nonsense mutations result in a premature stop codon being produced which results in a shorter protein.
Describe splice-site mutations.
Splice site mutations result in some introns being retained and/or some exons not being included in the mature transcript.
What do Nucleotide insertions/deletions result in?
Frame-shift mutations.
Describe Frame-shift mutations.
Frame-shift mutations cause all of the codons and all of the amino acids after the mutation to be changed. This has a major effect on the structure of the protein produced.
Name the four types of chromosome structure mutations.
Duplication, deletion, inversion and translocation.
Describe duplication
Duplication is where a section of a chromosome is added from its homologous partner.
Describe deletion.
Deletion is where a section of a chromosome is removed.
Describe inversion.
Inversion is where a section of a chromosome is reversed.
Describe Translocation.
Translocation is where a section of a chromosome is added to a chromosome, not its homologous partner.
How bad are chromosome structure mutations?
The substantial changes in chromosome mutations often make them lethal.
What is the importance of mutations and gene duplication in evolution?
Duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein.
