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Meiosis and linkage

Could someone clear this up for me, the textbook is confusing:

"Linkage refers to two or more genes that are located on the same chromosomes. The linked alleles (of these genes) are normally inherited together because they do not segregate independently at meiosis, unless chiasmata have been formed between them. At crossover, the alleles from one chromatid become linked to alleles on the other chromatid. Linkage reduces the number of phenotypes resulting from a cross"

Is the first sentence of the bold part referring to what generally happens during crossing over, or what happens with linked alleles? How does this reduce the number of phenotypes resulting from a crossover?

If someone could explain this a bit better I'd be very grateful :smile:

Reply 1

Dynamo123

Take the example of a gold watch. There are bands on it in a regular fashion. Now, the regular method to wear a watch is known quite well. Do it the other way round, so that you can see the front portion of the gold watch. over it you have joined the straps together. You'll notice that the bands which were, like close to each other are now facing each other oppositely, at the site of the strap only the bands do join. You can do it with your watch right now :smile:

As for gene linkage it is the staying of all genes on a single chromosome close to each other en bloc.It significantly reduces the chances of cross over during meiosis (think about the watch again). So that's that :smile: