Genetics: chromosome structure, testing & mutation effects Flashcards
describe the structure of a chromosome
one long arm, = q
one short arm, = p
centrosome in between arms holding them together
what is a translocation mutation
when parts of a chromosome are rearranged
what is an aneuploidy mutation
when you have a whole extra/missing chromosome
what other types of chromosome mutation are there( other than translocation and aneuploidy)
insertion, deletion and microdeletion
briefly describe x-inactivation
in females one X-chromosome in each cell is randomly switched off (keep in mind for X-linked conditions)
briefly describe what comparative genomic hybridisation(CGH) test and Array CGH test are
CGH = tests metaphase chromosomes, i.e. during cell division
Array CGH = sample is fragmented ahead of hybridisation
(compares no. of gene copies to template genome)
briefly describe what FISH testing is
uses fluorescence to highlight genes in situ - look for evidence of insertions/deletions
what are the different affects mutations can have
can alter; transcription, splice site, stop/start point, exon sequence or no effect
what types of gene mutation can occur
stop, missense, deletion or insertion(in/out of frame), triplet expansion
what is meant by penetrance
penetrance = likelihood of having the disease if you have the mutation
what is meant by expression
expression = variant in phenotype if you have the mutation
what is meant by a Mendelian disorder
mendelian disorder = high penetrance monogenic disorder that segregates in families by Mende’s law
what types of condition are mendelian disorders
autosomal dominant/recessive, X-linked recessive/dominant, mitochondrial, Y-linked
what types of condition are non-mendelian
methylation, imprinting, mosaicism, mitochondrial?
what is meant by a multifactorial disease
its caused by a complex interplay of genes and environmental factors
