Genetic Distance Between Genes On Different Chromosomes
3
3
Entering edit mode
10.8 years ago
Spandankeshav ▴ 160

If two genes are in different chromosomes then how can we measure the distances between them?

genetics distance chromosome gene • 6.6k views
ADD COMMENT
0
Entering edit mode

What do you mean with '''distance''' ? a recombinant frequency (cM ) ?

ADD REPLY
0
Entering edit mode

He could mean the physical distance (measured in micrometers or some suitably small unit). That would vary over the life of the cell.

ADD REPLY
0
Entering edit mode

He could mean physical distance, e.g. measured in microns rather than base pairs. That would vary over the life of the cell.

ADD REPLY
0
Entering edit mode

Yeah Pierre you are right. I mean recombinant frequency (cM).

ADD REPLY
0
Entering edit mode

changed the title. Come on, try to think of a better title when posting here.

ADD REPLY
13
Entering edit mode
10.8 years ago

The "recombination" frequency of two independent linkage groups (chromosomes) is defined as 0.5 because of Mendel's Second Law of Independent Assortment.

From wikipedia: "any alleles that are completely unlinked (e.g. alleles on separate chromosomes) have a 50% chance of recombination, due to independent assortment."

A recombination frequency of 0.5 implies two genes are "unlinked," regardless of whether they are on the same or different chromosomes.

ADD COMMENT
5
Entering edit mode
10.8 years ago

You calculate it in the same way as you do for genes on the same chromosome. If two genes are in linkage disequilibrium even in this condition, it may mean that they are involved in the same function. Note that you don't need to know whether two genes are on the same chromosome to calculate their genetic distance; in fact, Morgan's student Sturtevant did not even know the concept of chromosome when he coined the definition.

ADD COMMENT
0
Entering edit mode

"If two genes are in linkage disequilibrium even in this condition, it may mean that they are involved in the same function" could you please cite the source from where you got this information ? just for reading up

ADD REPLY
0
Entering edit mode

it just comes from the definition of Linkage Disequilibrium http://en.wikipedia.org/wiki/Linkage_disequilibrium . If two alleles of different genes on different chromosomes tend to be inherited together with a frequency different that what expected, it may be because they are associate with the same function and having the two alleles together gives some sort of positive advantage to the individuals. Of course, it may simply be the result of drift or hitch-hiking.

ADD REPLY
2
Entering edit mode
10.8 years ago

aside from the Chromosomal abnormalities there is no recombination/crossing over between two non-homologous chromosomes, so the genetic distance has no meaning here.

ADD COMMENT
2
Entering edit mode

it makes sense to calculate genetic distance between genes on different chromosomes, because if two genes are in linkage disequilibrium even in this condition, it may mean that they are involved in the same function.

ADD REPLY
0
Entering edit mode

thanks for the clarification Giovanni

ADD REPLY

Login before adding your answer.

Traffic: 2672 users visited in the last hour
Help About
FAQ
Access RSS
API
Stats

Use of this site constitutes acceptance of our User Agreement and Privacy Policy.

Powered by the version 2.3.6