Gene Mutations Flashcards
What is a gene mutation?
A gene mutation is the alteration of a base in a sequence of bases
When is a gene mutation most likely to occur?
During dna replication during the interphase of the cell cycle
What are mutagenic agents?
Certain factors that increase the frequency of gene mutations occuring
What can mutated genes result in?
A different amino acid sequence in the encoded polypeptide
What happens if the amino acid sequence is changed?
Then when the protein is modified into its tertiary structure, hydrogen and ionic bonds will form in different places and fold differently. This results in a different 3d shape therefore a non functioning protein
What are types of mutagenic agents?
High energy and ionising radiation disrupts the structure of dna
Carcinogens disrupt the structure of dna and interfere with transcription
What is an addition mutation?
- one extra base is added to the sequence
-all codons are altered and there is a frame shift
-could result in a different amino acid sequence therefore a non functioning protein
What is a deletion mutation?
-the deletion of a base from a sequence
-frame shift to the left
-could result in a different polypeptide chain therefore a non functioning protein
What is a substitution mutation?
-one base is substituted for another
-there is the same number of bases and no frame shift
-only one codon changes and it may still code for the same amino acid
What is an inversion mutation?
-a sequence of bases detach from the dna sequence but when they rejoin they are inverted
-results in a different amino acid sequence in this region
What is translocation?
A section of bases on one chromosome detached and joins another chromosome
This has a significant impact on gene expression and therefore the resulting phenotype
