1.4 Flashcards
mutation
are random changes in the DNA that can result in either no protein or an altered protein being synthesised
single gene mutations
is when the DNA nucleotide sequence is altered by substitution , insertion or deletion of nucleotides.
SG - deletion
-all amino acids from the nucleotide deletion site are altered .
- major change to protein structure
SG - insertion
all amino acids from the nuclotide insertion site are altered.
- major change to protein structure
SG - substitution
a subsititution only chnages on codon resulting in minor change to protein structure.
single gene substitutions include - missense , nonsense and splice-site mutation.
SGS - MISSENSE
one amino acid is changed this will have little effect on protein structure
SGS - NONSENSE
a stop codon is inserted this shortens the polypeptide chain so may become non functional.
SGS - SPLICE-SITE
Alters which coding/noncoding regions are retained during splicing of primary transcript
what causes frame shift mutations
insertion and deletion
what is a frame shift mutation
a frameshift mutation is when an altered codon is translated at the ribosome into a amino acid all the subsequent codons and thus amino acids are now changed , this may have a major affect.
- cystic fibrosis ( caused by frameshift deletion )
chromosome structure mutations
affect the whole chromosome or sections of the DNA . these alterations are duplication , deletion , inversion and translocation
CS duplication
added gene section from its homologus partner
CS inversion
a section of a chromosome is reversed
CS deletion
when a gene section is removed
CS translocation
gene section added to chromosome , not from its homologus partner
substancial change
occurs in the genetic material of chromosome mutations often makes them lethal .
