Dihybrid Crosses and Genes Relinked
Updated presentation for 2011.
Link to more class resources here: 10.2 Dihybrid Crosses and Gene Linkage
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Posted on May 12, 2011, in AHL, IBDP Biology and tagged polygenics, skin colour. Bookmark the permalink. 2 Comments.
i-Biology 
Mr. T,
Could you please explain how one knows which allele goes on which chromosome in a linked gene?
It seems that if the gene is XxLl, then the dominant genes will go together and the reccessive genes will go together on each chromosome, (XL and xl)?
If the genotype is XXLl though, the dominant gene will have to link with one of the reccessive genes (XL Xl…)
Is there a general rule?
Mr. Link
Good question Mr Link!
In the Biology subject guide, it states that they will use the standard notation for linked genes in questions, i.e. A B or a b. Another alternative notation is AB/ab, which denotes gene linkage, though this is not used in the subject guide.
You should not have to make the assumption of which allele is on which chromosome. I will add a slide to clarify this. EDIT – added to slides 47-49 (changes take a while to appear on embeds).
I hope this helps,
MrT