D1.3 Mutations in genes Flashcards
Function of non-coding sequences in genes (4)
regulators of gene expression
introns : found in eukaryotes, removed after transcription
telomeres : found at ends of chromosomes to ensure correct replication
genes for tRNA and rRNA
Define a mutagen
chemical or physical agent which can cause a mutation
Define a mutation (2)
changes to genetic composition of cell
change in order of bases in DNA strand
2 regions of pre-mRNA (2)
exons : protein coding regions
introns : non-protein coding regions
region of mRNA
exons : protein regions
Define post-transcriptional modification (2)
process where mRNA which is produced needs to be modified before translation
introns are removed to code for proteins using spliceosomes
Define spliceosomes
large enzymes found in nucleus
Define spontaneous mutation
mistake made when DNA is copied during production of gametes
3 Different types of mutation
Substitution
Insertion
Deletion
Features of single nucleotide polymorphisms (2)
occur when one nucleotide is replaced by another nucleotide in DNA sequence
effect on protein structure depends on whether substitution is synonymous or non-synonymous
Define synonymous SNPs (2)
known as neutral/same-sense mutations
do not change amino acid sequence due to degeneracy of genetic code
Define non-synonymous SNPs (3)
change amino acid sequence having different effects on protein function
non-sense = stop codon
mis-scence = different amino acid
Causes of frameshift mutations (3)
insertion
deletion
duplication
Impacts of frameshift mutations (3)
alters amino acid sequence coded by DNA sequence
addition of new nucleotides alters grouping of codons
mRNA transcript produced will have different codon structures
Examples of chemical mutagens (3)
mustard gas
nitrous acid
Formaldehyde
