Mutations Flashcards
(16 cards)
What is a gene mutation
Alteration of a base sequence for one gene.
When is a gene mutation likely to occur?
Spontaneously during DNA replication, during interphase.
What is the consequence of gene mutations in terms of proteins?
- When protein is modified into tertiary structure it will form H bonds and Ionic bonds in different places
- Folds differently
- Different 3D shape/tertiary structure
- Protein will have a different function/non functioning
- Active site no longer complementary to substrate.
What are the two mutagenic agents?
High energy and Ionising Radiation:
(radiation and ultraviolet light)
Carcinogens:
chemicals that alter the structure of DNA and interfere with transcription
(tobacco smoke, mustard gas, peroxides)
- mutagenic agents increase risk of spontaneous mutations
what is an addition mutation?
one extra base being added to the sequence
impact of addition mutation?
by adding one base all subsequent codons are altered
- altered codons could potentially code so different amino acids, resulting in non- functioning protein
- frameshift to the right
what is a deletion mutation?
deletion of a base in a sequence
impact of deletion mutation
by deleting one base all subsequent codons are altered
- altered codons could potentially code so different amino acids, resulting in non- functioning protein
- frameshift to the left
what is a substitution mutation?
one base being changed for a different base, but no. of bases remain the same NO FRAMSHIFT.
Impact of substitution mutation?
results in one coding changing and due to genetic code being degenerate may still code for the same amino acids so sometimes has no impact
What is an Inversion mutation?
A section of the DNA detaches from the DNA sequence and rejoins inverted
- section of code is back to front
Impact of inversion mutation?
Results in different amino acids being coded for in this region
- Affects the resulting polypeptide chain and therefore final protein
What is translocation?
A section of bases on one chromosome detaches and attaches to a different chromosome
Impact of translocation?
Significant impact on gene expression as section of chromosomes is likely to be multiple genes
- lots of proteins will be incorrect for the particular cell
- can result in change of phenotype
What is duplication?
A whole gene or section of a gene is duplicated so that two copies of the gene/section appear on the same chromosome
Impact of duplication?
Overtime, the second copy can undergo mutations which enable it to develop new functions
- source of evolutionary change
