mutations and genetic analysis Flashcards
what are the 3 types of chromosomal abnormalities?
numerical, structural and mutational abnormalities
what makes up around 50 percent of chromosomal abnormalities?
first trimester miscarriages
what is the aetiology of patau syndrome?
trisomy 13
what is the aetiology of edwards syndrome?
trisomy 18
what is the aetiology of downs syndrome?
trisomy 21
what is the aetiology of klinefelter syndrome?
Y chromosome along with 2 X chromosomes
what is the aetiology of turner syndrome?
monosomy - only a single x chromosome
what is non-disjunction?
failure of homologous chromosomes or sister chromatids to separate properly during cell division.
what are some symptoms of turner syndrome?
females are short of stature and infertile
neck webbing
widely spaced nipples
what are some symptoms of klinefelter syndrome?
tall stature, long limbs
infertile males with small testes
gynaecomastia in around 50%
mild learning difficulties
what are some examples of structural abnormalities in DNA?
balanced or unbalanced rearrangements translocations deletions insertions inversions
what are the two types of translocations?
reciprocal - involves breaks in two chromosomes with the formation of two new derivative chromosomes
robertsonian - fusion of two acrocentric chromosomes
what are some outcomes of unbalance translocation?
partial trisomy
partial monosomy
what is lost in robertsonian translocation?
the two short arms of the acrocentric chromosome, however, no genetic information is lost
what are the 2 classifications of genetic mutation?
non-coding
coding
what types of coding mutations are there?
silent
missense
nonsense
frameshift
what causes frameshift mutations?
insertion and deletion
what are the types of point mutation?
transitions and transversions
what classifies a point mutation as a transition?
purine > purine or pyrimidine > pyrimidine
what classifies a point mutation as a transversion?
purine to pyrimidine or pyrimidine to purine
what are some methods used to detect mutations?
PCR
gel electrophoresis
restriction fragment length polymorphism (RFLP) analysis
amplification refractory mutation system (ARMS)
DNA sequencing
what are the 3 steps of PCR and what temperatures do they take place at?
denature - 93-95 celsius
anneal- 50-70 celsius
extend - 70-75 celsius
what are the steps in gel electrophoresis?
separate DNA fragments by size
apply an electric field (DNA is negatively charged)
separation occurs through an agarose gel matrix
fragments of DNA are then visualized
what are some advantages of gel electrophoresis?
speed
ease of use
sensitive
robust
what are some applications of PCR?
DNA cloning DNA sequencing gene identification forensic medicine detection of mutations
what are some advantages of ARMS?
cheap
labelling not required
what are some disadvantages of ARMS?
need sequence information limited amplification size limited amounts of product infidelity of DNA replication electrophoresis required primer design critical
what are restriction endonucleases?
enzymes from bacterial cells protective mechanism degrade DNA of invading viruses recognise specific DNA sequences always cut the DNA at same site
what are some advantages of RFLP?
simple
cheap
non radioactive
what are some disadvantages of RFLP?
requires gel electrophoresis
not always feasible
what are some advantages of gene sequencing?
best option for detection of mutation
automated
can sequence a huge length of base pairs
what are some limitations of gene sequencing?
expensive equipment
poor quality sequence read.
