Gene Mutations Flashcards
`What is a mutation?
A mutation is any change to the quantity or the structure of the DNA of an organism
What is a gene mutation?
A gene mutation is any change to one or more nucleotide bases, or any rearrangement of the bases, in DNA
When might a gene mutation arise?
Gene mutations may arise during the replication of DNA
What type of gene mutation is the substitution of bases?
The substitution of bases is a gene mutation in which a nucleotide in a section of a DNA molecule is replaced by another nucleotide that has a different base
What are the three different consequences that result from substitution?
1* Substitution can result in the formation of stop codon and the polypeptide being prematurely stopped, so the final protein created is significantly different, disabling the protein from performing its normal function
2* Substitution can result in the formation of a codon that codes for a different amino acid, as the protein of which this polypeptide is a part of may differ in shape and not function properly
3* Substitution can result in a different codon that still produces the same amino acid as before. This is because the genetic code is degenerate so the mutation has had no effect on the polypeptide produced
What type of gene mutation is the deletion of bases?
The deletion of bases is the loss of a nucleotide base from a DNA sequence
What does a deleted base cause?
A deleted base causes a frame shift which shifts the reading frame of the codon to the left by one letter
What is does a frameshift caused by deletion result in and lead to?
A frameshift caused by deletion will cause the gene to be read wrongly in the codon and alter the coded information. Most the triplets will differ, which lead the different polypeptides being formed and the production of a non - functional protein
What could happen if deletion occurs at the start of a DNA sequence, compared to if the deletion occurred at the end of the DNA sequence?
One deleted base at the start of a DNA sequence could alter every triplet in the sequence. A deleted base near the end of a sequence is likely to have a smaller impact but still have consequences
What are the four other types of gene mutation?
1* Addition of bases
2* Duplication of bases
3* Inversion of bases
4* Translocation of bases
What is involved in the genetic mutation which has the addition of bases?
The addition of bases involves an extra base being inserted into the sequence. A frame shift usually occurs altering the whole sequence of triplets - code is shifted to the right, instead of the left.
What is the exception in the addition of bases that means there will be no frame shift?
If three bases are added to the DNA sequence there will be no frame shift
What does an addition of base genetic mutation lead to?
An addition of a base results in a polypeptide which is different from the one initially meant to be produced from the non - mutant gene, but not to the same extent of a frame shift
What is involved in the genetic mutation which has the duplication of bases?
The duplication of bases involves one or more bases being repeated and producing a frame shift to the right
What is involved in the genetic mutation which has the inversion of bases?
The inversion of bases involves a group of bases being separated from the DNA sequence, then rejoining at the same position but in the reverse order
