1.6 Mutations Flashcards
What are mutations?
Changes in the DNA that can result in no protein or an altered protein being synthesised.
What does a single-gene mutation involve?
Alteration of a DNA nucleotide sequence as a result of substitution, insertion or deletion of nucleotides.
What is a substitution mutation?
When one nucleotide is replaced by another.
What is an insertion mutation?
When a nucleotide is added into the base sequence.
What is a deletion mutation?
When a nucleotide is removed front eh base sequence.
What mutations cause a frame-shift mutation?
Insertion and deletion.
What is the are the two possible mutations that can occur due to substitution?
Missense and nonsense.
What does a missense mutation do and what effect does this have?
Results in one amino acid being changed for another and can result in a non-functional protein or have little effect on the protein.
What does a nonsense mutation do and what effect does this have?
Nonsense mutations result in a premature stop codon being produced which results in a shorter protein.
What is a splice-site mutation and what affect does it have?
Results in some introns being retained and/or some exons not being included in the mature transcript. Inclusion of introns will cause extra amino acids which will alter the sequence and, therefore, the function of the protein.
What is a frame-shift mutation and what effect does it have?
Causes all of the codons and all of the amino acids after the mutation to be changed. This has a major effect on the protein produced.
What are the four chromosome structure mutations?
Duplication, deletion, inversion and translocation.
What is a duplication mutation?
When a section of a chromosome is added from its homologous partner.
What is a deletion mutation?
Where a section of a chromosome is removed.
What is an inversion mutation?
Where a section of a chromosome is reversed.
What is a translocation mutation?
Where a section of a chromosome is added to a chromosome that is not it’s homologous partner
True are false? The substantial changes in chromosome mutations often has little effect.
False - often they are lethal.
Can duplication mutations be beneficial?
Duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein.
Why are mutations important in evolution?
They are the only source of genetic variation. Most mutations are harmful but there is potential for a mutation to give an organism a selective advantage to increase its chances of survival.
