Topic 6: Mutations Flashcards
Point mutation
affect single or small number of nucleotides
Substitutions
transition or transversion, point mutation
transition
purine to purine OR pyrimidine to pyrimidine
transversion
purine to pyrimidine OR vis versa
Indel
Insertion/deletion mutation (addition, deletion)
frameshift
add or delete base pairs (may occur by replication slippage at poly dN)
repeated sequences
may result in larger indel mutations
-cross over and loop is deleted
(centromere and telomere)
interstitial
in the middle of the chromosome
terminal
at the end of the chromosome
intra-genic
within the gene, deletion
intergenic
between 2 genes
multigenic
more than one gene affected (deletion)
duplications
extra material for mutation
inversion
paracentric or pericentric
-creates difficulty in homologous pairing and therefore unbalanced products
paracentric
away from the centromere
pericentric
including the centromere
anticipation
diseases where you see changes in severity from generation to generation
Fragile X syndrom
mental development handicap, sex-linked on X chromosome, more common in males
translocations
involves 2 different nonhomologous chromosomes, can be caused by double strand breaks
- reciprocal or unbalanced
aneuploidy
change in chromosome number
caused by nondisjunction
nondisjuction
impropoer separation of chromosomes during cell division
monosomy
absense of one member of a chromosome pair
euploidy
normal number of chromosomes
polyploidy
multiple chromosome sets, triploid, tetraploid, octoploid (strawberries)
mobile genetic elements
ie, plasmids
DNA sequences orginating in viruses and integrated into genomes
synongmous
no change in amino acid (but there IS a change in DNA), silent
missense
conservative/nonconservative
- one amino acid is substituted for another
conservative missense
same biochemical properties as substituted amino acid
nonconservative missense
different biochemical properties as substituted amino acid, more likely to change function of protein
nonsense
change of amino acid to a stop codon
null
no effect, silent mutation (of protein)
leaky
partially functioning (of protein- only some is made or not very functional)
neutral
change but not a large effect on protein function (location is important)
morphological mutation effects
affect form (size, shape, number, colour, etc)
lethal
recessive, de novo (if not inherited, dominant, “novel”)
conditional mutation
mutant phenotype only expressed in certain conditions (ie. temp)
restrictive condition
see mutant phenotype
permissive condition
see wild-type phenotype
suppressor
second mutation compensates for primary mutation
regulatory mutation
occurs outside of coding region (ie. promoter and splice sites)
loss-of-function
hypomorph, null
gain-of-function
hypermorph
haplosufficient
only one allele is necessary for phenotype
haploinsufficient
heterozygotes: one copy of “normal phenotype” is not enough (mutant allele is dominant)
ethylmethane sulfonate (EMS)
alkylating agent- transitions
adds ethyl group onto G which miss-pairs bases (CG to AT or GC to TA)
deamination
base alteration, transitions
UV light
photo products of adjacent pyrimidines (thymidine dimer), transitions
-double stranded DNA breaks also
2-aminopurine (2-AP)
adenine analog
GC to AT or AT to GC- transitions
5-bromouracil (5-BU)
thymidine analog
GC to AT or AT to GC- transitions
Aflatoxin B1 (AFB1)
bulky adducts cause apurinic sites
GC to TA transversions
- become unweilding, base may fall out
Acridine orange
intercalating agent
frameshifts
intercalating agent
planar molecules, insert into DNA molecule and makes DNA longer
Ethidium bromide
intercalating agent, used in lab as a dye for DNA - fluoresces under UV light
pseudogene
non-functioning copy of a gene, caused by duplication
transformation
the change of a normal cell into a cell that is immortal (HeLa cells)
can divide forever
tumor suppressor genes
“brakes”, stop normal cell division
- inactivating mutations cause cancer
proto-oncogenes
“gas”, promote cell division
- activating mutations cause cancer
apoptosis
programmed cell death
