karyotype Flashcards
what is the difference between chromatin and nucleosome
Chromatin is a structure of DNA wrapped around histone. nucleosome is when that DNa is wrapped around 8 core histones
what characterizes a lateral transfer of genes?
when the DNA in the human genome is from other species like a viral DNA incorporating into a human genome
how can you tell how old a particular set of genes have diverged from when it was originally inserted into the human genome?
if you sequence the original gene and sequence the one found in humans, the longer its divergent, the longer ago the insertion happened
what about repeated sequences makes it so easy to cause color blindness?
color blindness is caused by a recombination between the gene for green sight and red sight that are repeated sequence With almost identical sequcenes on the X chromosome. Because they have identical sequences it is easy for a recombination to between those two genes. When a recombination happens, one X chromosome can have 1 reg gene and 2 green genes and the other X will have only 1 red gene and no green gene. If the only with no gree gene is passed on, that offspring will not be able to tell the difference between red and green.
what is the difference between a recombination and a contigious deletion? how do you diagnose a contigious deletion?
recombination is usually within short tandem repeated genes that are close in sequence. Contingious deletions are recombinations that happen within LARGE repeats that lead to deletions of blocks of DNA that contains multiple genes. You diagnose this with FISH with a probe for the delted sequence. if it doesnt find the sequence, it wont fluoresce and you can conclude it has indeed been deleted.
what do you call tandem repeats that are hundreds of base pairs long? where are they found?
these are satelite sequences and there are throusands of them located near the telomeres and the centromeres
what is a microsatelite and what is it used for?
microsatelite are repeats of like 2 nucelotides that are like a cassette tape that stuck and just goes CACACACACACA. It is used for identifying specific chromosomes during genetic counseling because each of the 4 from each parent will be different.
retrotransposons are thought to account for about 25% of the complexity in the human genome, what is the enzyme integral to retrotransposon integration and what is its product?
use reverse transcrirptase to make double stranded complementary DNA (ds cDNA) from mRNA
what is the name of an mRNA coading a reverse transcriptase?
Long Interspersed nuclear element (LINE)
what is a pseudogene?
copies of cellular mRNA that lacked a promoter. it is not transcribed because it lacks a promoter
G-banding is done on cells arrested in
metaphase. this shit is time sensitive
centromere position gives different chromosomes different names what are they?
metacentric
submetacentric
acrocentric
how are the chromosomes numbered?
a
G banding is done on metaphase cells. but FISH is done on
interphase cells and metaphase cells but metaphase cells have better resolution because the cells are more condensed.
what is one clinical use of FISH?
prenatal diognosis and identifying trisomies and deletions
CGH is used to test the entire genome for any changes, how would you interpret the results
if green is the person’s DNA and red is the refernce/ probe. If it turns yellow that is a good sign you know the person has the sequence at that spot in tact. green means there is too much of that particular gene and red means that sequence is gone in your patient.
when it comes down to it what determines chromosome identity
Which ever chromosomes centromere is left is the chromosome who that is. see picture
in robertsonian chromosomes there is fusion between ___ and ___ and the ___ arms are lost
there is a fusion between 14 and 21 and the P arms of the choromsomes are lost. this is a an example of a non-reciprocal translocation. most translocations happen in acrocentric chromosomes. see picture
a pericentric inversion involves
the centromere. see picture
