Genetic Variation Flashcards
Codon Rules
Sequence of bases in a codon follow direction of translation; nonoverlapping, read in fixed reading frame; unambiguous; degenerate
Probability of mutation
depends on the size of the gene; larger the gene, likelier the mutation
Base-pair Substitution
one base pair is replaced by another
Nonsense mutation
base pair substitution where a stop codon is inserted
Missense mutation
base pair substitution where another amino acid is added
Silent mutation
base pair substitution where amino acid remains unchanged
Single gene mutations
include insertions and deletions that cause frameshifts
Mobile elements
DNA sequences that are capable of inserting themselves or copy themselves into other areas of the genome
Expanded repeats
expansion of tandem repeats
Fragile X Syndrome
expansion of CGG trinucleotide repeat in FMR1 gene on the X chromosome
Duplication
large repeats of entire genes
Promoter mutation
can increase affinity of RNA polymerase to promoter sequence causing decreased transcription and decreased production of the gene product
Splice site mutation
introns are nor removed or spliced incorrectly
Gain of function mutations
quantitatively alter the action of a gene; activation of a gene which is normally inactive
Loss of function (knock out or null) mutations
result in complete inactivation of a gene or production of nonfunctional gene protein
