lecture 4 Flashcards
in FISH what size must the probe be?
smaller than the deletion
why must the probe be smaller than the deletion
to discriminate between wild type and mutant allele
what happens if the probe is bigger than the deletion?
it will hybridize with the mutant allele and not be able to discriminate between them
what is special about metaphase FISH?
can see all the chromosomes
mutation that cause DiGeorge Syndrome?
22q11 deletion
symptoms of which disease? CATCH 22 cardiac defects abnormial facies thymic hypoplasia cleft palate hypocalcemiaf from parathyroid aplasia chromosome 22 deletion
DiGeorge Syndrome
whats the advantage of MLPA over FISH
**review
what is array comparative genome hybridization (array-CGH)?
compare cells from normal cells (control) to cells from a patient
label both samples with diferent fluorochromes and hybridize to a plate
how is the result displayed in CGH?
plot ratio of green to red, each black spot represent a locus.
what is the problem with CGH?
only detect numerical not unbalanced abnormalities.
cant detect inversions for example
in a CGH graph what does it mean when the spots go down or up?
down: deletion
up: addition
general rule for an autosomal dominant disease?
will die out in the family, the individuals are selected against usually
sanger (dideoxy) DNA sequency?
based on DNA synthesis, durint the synthesis trigger random termiation at specific bases.
these random termiations are caused by dideoxy NT.
what happens when dideoxy is incorporated into the synthesis? why?
stops transcription. because it doesnt have a 3’ OH
Dye-terminator sequence?
label the dideoxy nucleotide, so instead of having to use gel electrophoresis to separate the fragments
advantage of dye-terminator sequencing?
can use higher voltage to separate the fragments,
its faster
it doent use radioactive labels
how are fragments separated in dye sequencing ?
separated by size using capillary electrophoresis
how are results interpreted in dye terminator sequencing?
the detector plots the fluorescent signal in a sequence chromatogram
R200Q mutation
Arginine at position 200 is replaced by glutamine
R200Q mutation
Arginine at position 200 is replaced by Q
notation to express introns and exons?
Intron: lower case
exon: upper case
what type of mutation causes Beta-thalassaemia?
NULL mutations in the Beta-globin gene
what cant the next generation sequencing be used for?
organism without a reference genome. (de novo sequence) like a new species of bacteria that is causing a disease
what are the advantages of using next generation sequencing?
- orders of magnitude faster and less expensive
- useful for whole genome re-sequencing
