UNIT 1 - KA4

Mutations are changes in the DNA that can result in no protein or an altered protein being synthesised

A mutation is a change to the genetic structure of an organism

A genetic disorder is a condition or a disease that can be show to be directly related to an individuals genotype

chromosomal structure mutations which involve a change in the structure of a chromosome ( this means a lot of genes are involved not just one)

Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of substitution , insertion or deletion of nucleotides

1- missense 2- nonsense 3- splice site 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

Nonsense mutations result in a premature stop codon being produced which results in a shorter protein

Splice site mutations result in some introns being retained and/or some exons not being included in the mature transcript

Nucleotide insertions or deletions result in FS mutations

As a result it is highly likely that the altered protein will not be able to function properly

Frame shift mutations (caused by insertion and deletion) cause all of the codons and all of the amino acids after the mutation to be changed. Whereas substitution mutations only effect a single amino acid

The mutations can be classes as : duplication, deletion, inversion and translocation

Deletion is where a section of a chromosome is removed

Duplication is where a selection of a chromosome is added from its homologous parter

Inversion is where a section of chromosome is reversed

Translocation is where a section of a chromosome is added to a chromosome, not it’s homologous partner

The substantial changes in chromosome structure mutations often make them lethal

Chromosome mutations have a lethal effect as the changes to the genetic material are substantial (and effects a lot of genes)

single gene mutations which involve the alteration of DNA nucleotide sequence within a single gene

As mRNA is read as a series of codons, insertion or deletion of a nucleotide causes every codon from the site of mutation to be altered and therefore every amino acid coded for will be altered.