Unit 1 - KA 6: Mutations Flashcards
Define the term mutation.
A mutation is a random change to the DNA sequence of an organism.
What may a mutation result in?
An altered protein or no protein being expressed.
Name the 3 types of mutation that can occur within a single gene.
Substitution
Insertion
Deletion
Describe nucleotide substitution.
One nucleotide is changed for a different one.
One amino acid is affected.
Describe nucleotide insertion.
An extra nucleotide is added.
All amino acids after are affected.
Frame shift mutation.
Describe nucleotide deletion.
A nucleotide is left out.
All amino acids after mutation are affected
Frame shift mutation
What are the two types of mutation that result in frameshift?
Deletion
Insertion
Describe the effect frameshift on protein structure
Every codon and therefore every amino acid coded for is altered from the point where the insertion or deletion has occurred.
Since all the amino acids after the point mutation will be affected, a new protein will be made.
Describe a missense mutation and its effects.
One amino acid is changed for another.
May result in a non-functional protein or have little effect on the protein.
Describe a nonsense mutation
As result of substitution, a stop codon is coded for prematurely. This forms a shorter polypeptide chain that is shorter than intended and is unable to function
Describe a splice site mutation
Nucleotides at a splice site are changed.
Some introns may be retained and/or some exons may not be included in the mature transcript
Name the 4 types of chromosome structure mutations
Duplication
Deletion
Inversion
Translocation
Describe a duplication chromosome mutation.
Duplication is where a section of a chromosome is added from its homologous partner.
Describe a deletion chromosome mutation
This is where a section of chromosome is removed
Describe an Inversion chromosome mutation.
A section of chromosome is reversed
Describe a translocation chromosome mutation
A section of a chromosome is removed and added to another that is not it’s homologous partner.
Define the term homologous partner.
Homologous chromosomes are matching pairs that are similar in length, gene position and centromere location.
The genes may contain different alleles
Describe the impact that substantial change in chromosome structure has on an organism.
Substantial changes are often lethal
Describe the benefit of duplication
Duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce a protein. This means the duplicated gene can be mutated without having an impact on the protein expressed from the original gene.
