Mutation Flashcards
Mutation
Mutations are changes in the DNA that
can result in no protein or an altered protein
What are the three types of gene mutation?
Substitution, Insertion and deletion.
What are the three types of substitution?
Missense, nonsense and splice site
Describe a substitution mutation.
A substitution mutation occurs when one nucleotide is replaced by another.
Describe an insertion mutation.
Insertion mutation is where an extra nucleotide is inserted into the DNA.
Describe a deletion mutation.
A deletion mutation is where a nucleotide of DNA is removed.
Describe a frame shift.
Insertion and deletion are frame shift mutations which cause all of the codons of the amino acids after the mutation to be changed. This has a major effect on the structure of the protein produced.
Describe a Missense.
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
Nonsense mutations result in a premature stop codon being produced which makes the protein shorter.
Describe splice-site mutation.
Splice-site mutations result in some introns being retained and some exons not being included in the mature transcript.
Example of substitution missense.
PKT or Sickle cell disease
Example of substitution nonsense.
Duchenne muscular dystrophy
Example of substitution splice-site.
Beta thalassemia
Example of insertion.
Tay-Sachs disease
Example of single gene deletion.
Cystic fibrosis
Example of chromosome Deletion.
Cri-du chat syndrome
Example of duplication.
Common cause of cancer.
Example of translocation.
Chronic myeloid leukaemia or Familial Down’s syndrome
Example of inversion.
Haemophillia A or Hunters Disease or Muscular dystrophy.
Describe Chromosome deletion.
Deletion is where a section of chromosome is removed.
Describe duplication.
Duplication is where a section of chromosome is added from it homologous partner.
Describe inversion.
Inversion is where a section of chromosome is reversed.
Describe translocation.
Translocation is where a section of chromosome is added to a chromosome, not its homologous partner.
Why are chromosome mutations more lethal than single gene mutations?
Chromosome mutations often involve a substantial change to the chromosomes structure. This may involve the alteration of several functional genes. This substantial change to the chromosomes often makes them lethal.
