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Linkage maps - Genetics

I’ve looked online and it’s really hard for me to still understand. Was wondering if anyone who has genetics knowledge could help me with revision for an upcoming exam?

Basically - I don’t understand what a linkage map is, and how do I actually do one?

Reply 1

bioenthusiast

also - does anyone have any good links for websites with good examples for this sort of thing?

Reply 2

OxFossil

Original post by bioenthusiast

also - does anyone have any good links for websites with good examples for this sort of thing?

Basically, a linkage map is a way of mapping the location of genes on a chromosome by discovering how often particular genes are inherited together. In principle, this should approximate to a physical map, because the closer two genes are to each other, the more often they will be inherited together. (in practice, this turns out not to be the case all the time, but its a good place to start).

To make a linkage map, the traditonal method is to choose the characters you wish to study, and see how often the offspring of a cross between parents with a mixture of those characters retain both those characters. If this happens very often, the genes for those characters are likely to be close together, but if the offspring frequently have just one or other, that implies the genes are frequently split up during recombination because they are far apart. By doing many such crosses, you should eventually get a reliable estimate of the relative distances between different genes and so be able to make a map of where the genes are located on the chromosome relative to each other.

This seems a pretty good introduction - but its hard to answer your question without your saying what your specific difficulty(s) is.

https://www.khanacademy.org/science/biology/classical-genetics/chromosomal-basis-of-genetics/a/linkage-mapping