UNIT 2 - mutations Flashcards
what is a genetic mutation?
its a permanent change to the sequence of bases in DNA
what is somatic mutation?
mutation occurs in body cells during the life of organisms
what is germ-line mutation?
mutation occurs in gametes and are passed onto off spring
what are the 3 causes of mutations?
- replication errors
- mutagens
- transposons
what are replication errors in mutations?
is very rare, DNA polymerase functions to proofread and repair errors in replication
what are mutagens?
environmental factors that cause changes to the DNA sequence
what does repair enzymes do?
monitor and repair irregularities
what are transposons?
(jumping genes) sequences of DNA able to move within or between chromosomes
what happens if a mutation affects the amino acid sequence of a protein?
the structure of the protein almost always affected
what are the 2 types of mutations?
frameshift mutation and point (substitution) mutations
what happens in a point (substitution) mutation?
there is a change in a single nucleotide
what codons are unaffected in a point (substitution) mutation
downstream codons
what is nonsense in a point (substitution) mutation?
there is an early stop codon - transcription stops prematurely
what is silent in a point (substitution) mutation?
no change to amino acid
what is Missense in a point (substitution) mutation?
different amino acid in sequence
what is a frameshift mutation?
reading frame is shifted - all downstream codons are affected
what is insertion in a frameshift mutation?
one or more nucleotide(s) added to sequence
what is deletion in a frameshift mutation?
one or more nucleotide(s) removed from the sequence
where do chemical reactions occur?
in the enzymatic “pathway”
what happens if a mutation occurs in enzyme 2 causing it to be non-functional?
the pathway can not be completed
what is deletion in a chromosomal mutation?
End or segment of chromosome is lost
what is duplication in a chromosomal mutation?
segment is repeated
what is inversions in a chromosomal mutation?
segment breaks off and is reattached at 180 degrees
what is translocation in a chromosomal mutation?
segment moves from one chromosome to another
