C2 use of polymorphisms in mapping Flashcards
what is linkage a measure of
how far apart genes are from each other
what is linkage
how likely a meiotic recombination event is between 2 loci
what did RFLPs, DNA seq, gel electrophoresis/southern blotting, PCR allow
polymorphisms without corresponding traits/phenotypes to be used as genetic markers
are the alleles of 2 microsatellite loci always inherited together, mostly together, or 50/50 chance
what does this indicate
complete linkage
partial linkage
no linkage
what is partial linkage
meiotic recombination (croos-over) between M1 and M2
frequency of recombinants proportional to physical distance apart
what is partial linkage
meiotic recombination (cross-over) between M1 and M2
frequency of recombinants proportional to physical distance apart
what is no linkage (unlinked)
independently segregating, inheritance of one allele at one locus has no influence on an allele at other locus
in terms of linkage what does phase mean
on the same chr
in terms of linkage what does haplotype mean
order of in-phase alleles along chr
what are linkage maps based on
frequency of marker separation during meiosis through generations
what is the engine of the linkage map study
meiotic recombination
units of linkage measurement
human genome - cM (centimorgan)
1cM= recombination fraction of 1/100 meioses
(physcially eqvn to between 0.7 and 1 Mb of DNA)
what human disorders were located by linkage
cystic fibrosis
huntingtons
breast cancer
genetic map problems for disease gene identification and human genome seq
-genetic mapping is a mathematical exercise
-only provides a rough idea of where markers are and where disease gene is located
how do you collate, organise and distribute huge quantities of DNA to make a physical map
-a library
(storage/duplication/distribution)
-a database
(relationships)
why do we need to clone DNA into genomic libraries
a whole genome is too big and complex- limited in quantity
libraries offer infinite ‘photocopies’ (clones) of any bit of the genome
how is DNA cloned into library
DNA strands chopped up and stored to make a genomic DNA library
what do natural bacteria sometimes carry on plasmids/episomes
genetic material
molecular biologists can engineer the plasmids to do what
carry bits of foreign DNA of interest
what happens to the engineered bacteria and why do scientists need them
bacteria become photocopies; producing infinite quantities of identical (cloned) copies of that DNA
needed for analysis
what is the restriction enzyme used to cut DNA at specific seq in genetic engineering
EcoRI
in genetic engineering what is the specific sequence that DNA is cut at
GAATTC
after DNA is cut in genetic engineering what happens
the cut ends have overhangs which allows them to reform in the presence of ligase
5 stages of making a DNA clone library summary
- human genomic DNA broken down
- fragments placed in vector
- stored in bacteria or yeast as a clone library (BACs, YACs)
- single bacterium with one BAC in it will grow into a clonal pop/colony
- (libraries can be made from mRNA in tissue, convert to cDNA)
