Mutations Flashcards
What is a mutation
A change to the quantity or base sequence of DNA
What causes mutations?
1) spontaneous mutation
2) mutagenic agents
How would the arrangement of the bases in DNA change?
1) deletion of bases
2) substitution of bases
SUBSTITUTION MUTATION
NAME THE 3 types of substitution mutation and describe the process and effects
1) NONSENSE–> mutation leads to a stop codon meaning the polypeptide would stop forming early and therefore the proteins tertiary structure would be altered( hydrogen, ionic and disulphide bonds wouldn’t form in the right places) and therefore the proteins won’t be able to carry out its function.
2) MIS-SENCE–> mutation leads to a different amino acid being coded for meaning there polypeptide sentience would be different. The effects depends on the role of the amino acid in the protein. E.g. Cystic fibrosis.
3) SILENT MUTATION–> mutations when the substitution base still causes a codon that coded for the original amino acid therefore not changing the polypeptide sequence.
DELETION MUTATION
what happens when there is a deletion mutation?
A nucleotide is most from the sequence causing a FRAME SHIFT. This could lead to almost the whole polypeptide sequence being different depending on where the mutation occurs!
What is a chromosome mutation?
Change in the structure or number of whole chromosomes
What is non-disjunction in terms of chromosome mutation?
During meiosis, individual homologous pairs of chromosomes fail to separate meaning in fertilisation the off spring will have 1 less/1 more chromosome in the both. E.g. Down’s syndrome
What is polyploidy?
When the gametes of an organisms carried a diploid number of chromosomes and therefore meaning their chromosomes can line up in homologous pairs during meiosis
Why are hybrids usually infertile?
They usually receive different numbers of chromosomes in the game yes of each parent and therefore their chromosomes can’t come together in their homologous pairs and line up in meiosis
