Unit 1.4 Mutations Flashcards
What are mutations
Rare & random changes in the DNA that can result in no protein or an altered protein being synthesised
The 2 types of mutation
Single gene & chromosome structure
What can increase the rate of mutation
Mutagenic agents
Examples of mutagenic agents
Mustard gas, X rays & UV light
What are genetic disorders
Conditions/ diseases that are directly related to an individuals genotype
What causes genetic disorders
Mutations in the DNA sequence
Where do gene mutations occur & what does this involve
Within genes & involves alterations to the DNA nucleotide sequence- this alters the sequence of bases on the DNA
What is single gene mutation
Change in one nucleotide
What are the 3 types of single gene mutations
Substitution, insertion & deletion
What happens in substitution
One nucleotide is swapped for another nucleotide
What can substitution result in
Missense, nonsense, or splice-site mutations
What does missense mutations result in
One amino acid being changed for another- which may result in a non-functioning protein or have little effect on the protein
What are nonsense mutations
Mutations that result in a premature stop codon being produced which results in a shorter protein
What are splice-site mutations
Mutations that result in some introns being retained and/or some exons not being included in the mature mRNA transcript
What can nucleotide insertions or deletions result in
Frame-shift mutations
What do frame-shift mutations cause
All of the codons & all of the amino acids after the mutation to be changed
What do frame-shift mutations have a major effect on
The structure of the protein produced
What happens in insertion
One nucleotide is added to the DNA sequence
What happens in deletion (in single gene mutation)
One nucleotide is removed from the DNA sequence
What are chromosome structure mutations
Changes in the order or number of whole genes within a chromosome
What are the 4 types of chromosome structure mutations
Duplication, deletion, inversion & translocation
What is duplication
When a section of a chromosome is added from its homologous partner
What does duplication result in
Extra genetic information is present on the same chromosome
What is cancer commonly caused by
Duplication of certain genes
What happens in deletion (in chromosome structure mutation)
A section of a chromosome is removed
What happens in inversion
A section of a chromosome is reversed
What happens in translocation
A section of a chromosome is added to a chromosome- not its homologous partner
What is a result of translocation
Problems occur during pairing of homologous chromosomes, & the gametes formed are often not viable
What type of mutation is PKU
A substitution missense mutation
Where does the PKU mutation occur
On chromosome 12
Which amino acids do we obtain from protein in our diet
Phenylalanine & tyrosine
