MCBHD Flashcards
What are the principles of genetic linkage? (5)
Tendency for alleles at neighbouring loci to segregate together at meiosis
Therefore to be linked, 2 loci must lie v close together
Alleles at linked loci = halotype
Halotypes mark chr segments which can be tracked thru pedigrees + pop
Cross-overs are more likely to occur b/w loci separated by some distance than those close together
What is recombination frequency (RF/θ)? (3)
No. of recombinants/
no. of recombs + non-recombs
Describes proportion of recombinants in total no. of offspring
Therefore RF is how frequently recombination occurs in a family
What happens loci are far apart? (5)
Independent reassortment No pattern of whether you get A1, B1/A2, B2 or recombination Value of θ therefore tends towards 0.5 Therefore no linkage b/w A + B loci Linkage equilibrium
What happens when loci are close together? (4)
Much less likely that recombination occurs
Probability of keeping parental haloytpes/seeing no recombination increases
Value of θ tends towards 0
Linkage disequilibrium
What does a lack of recombination indicate? (1)
That loci are close together
What does recombination indicate? (1)
That loci are far apart
What is linkage? ()
Phenomenon of 2 loci being close together
+ therefore alleles on the same chr being likely to be inherited together
If 2 alleles from diff loci are co-inherited more that would be expected by chance they are likely to be in what? (1)
Linkage disequilibrium
What are microsatellites? (1)
Di-, tri-, tetra- nucleotide sequence with a variable number of repeats
No. of repeats is constant within an individual
No. of repeats b/w individuals
Can be used as form of genetic marker
How can we detect microsatellites? ()
Isolate DNA from individuals to be studied
Design primers specific to unique flanking sequence
