3.8.1 Altering DNA Alters Protiens Flashcards
When do gene mutations occur
During DNA replication
What are the 6 gene mutations
Addition
Deletion
Substitution
Inversion
Duplication
Translocation
Describe an addition mutation
Extra base inserted into base sequence, causes a frame shift to the right,sequence of triplets becomes altered
Describe a deletion mutation
Loss of a base from DNA sequence, causes a frame shift to the left, triplets are altered, so will the amino acids they code for, polypeptide will be different leading to a non functional protein
What’s a substitution mutation
A nucleotide in a section of DNA is replaced by another nucleotide, could cause three consequences
Formation of a stop codon, production of polypeptide coded for stops early, protein is different and can’t perform its normal function
Formation of a codon for a different amino acid, polypeptide will have one different amino acid, the protein may have a different shape and not function
Formation of a different codon but codes for the same amino acid as the original codon, genetic code is degenerate, amino acids can be coded for by more than one codon, no effect on the polypeptide
What’s an inversion mutation
A group of bases become seperate from the DNA sequence, they rejoin in an inverse order, effects amino acids
What’s a duplication mutation
One or more bases are repeated, causes a frame shift to the right
What’s a translocation mutation
A group of bases are separated from DNA sequence on one chromosome and are inserted into the DNA sequence of a different chromosome, significant effects on gene expression, abnormal phenotype
When do mutations occur
Spontaneously
What are mutagenic agents
Increase the rate of mutations
What does a mutation result in
Different amino acid sequence in the encoded protein
What’s a frame shift
A mutation causes all base triplets downstream from the mutation to change
