5. A series of two point crosses is carried out between...

5. A series of two point crosses is carried out between genes for brown eyes (bw), and arc wings (a), vestigial wings (vg) , ebony body color (e), and curved wings (cv). The following number of nonrecombinant (NR) and recombinant progeny (R) were obtained from each cross. Sum of NR and R equals total progeny. Genes | NR Progeny | R Progeny a,bw | 2128 | 112 a, cv | 2602 | 824 a, e | 3125 | 3125 a, vg | 5173 | 2378 bw, cv | 4612 | 1704 bw, e | 4143 | 4143 bw,vg | 2797 | 1432 cv, e | 3110 | 3110 cv, vg | 2103 | 302 e, vg | 4567 | 4567 Using these data form two-point crosses, create a genetic map for these genes, providing the order of the genes and your best estimates of the distances between them.

Transcript

00:01 In this particular question, there is a lot going on.

00:03 There's a lot of information.

00:04 So i'm just going to do a snippet of it, just this first top of the table and show you how to do.

00:10 I'm going to give you this walkthrough.

00:12 So basically, we're told there's a lot of different genes that we're looking at.

00:15 There's a, there's bw, there's cv, there's e, there's vg, and we want to know how far apart are all of these genes in what order they're in.

00:24 So what we're going to do is first off, we know that for each of these different genetic combinations, we have the two genes, we have the non -recombinants, and then the recombinants for those genes.

00:41 So that information is going to help us find out what is the percentage of recombinants, and that will help us find the distance in map units.

00:51 So first thing you want to do is find the total for each selection.

00:58 So for a and w, total would be the non -recombinates plus the recombinants.

01:06 So 2 ,122, give this 2 ,240.

01:12 So you want to bust out your calculator for this one.

01:15 And then for a and cv, 2 ,602 plus 824, 3 ,500.

01:25 426.

01:27 So you'll just do that for all of the ones in your table.

01:31 And again, i'm just doing part of your table to give you a walk there.

01:36 So for all of the a genes and the distance from a to all of those, we're going to use these totals.

01:44 So to find the distance, you're going to take r.

01:49 It's in the case of a and bw, 112, divided by the total that we just calculated 2 ,240.

02:02 When you do that math, you should get a decimal number.

02:05 In this case, we got 0 .05.

02:09 And if you want to know the distance in map units, all you have to do is move your decimal place twice to the right.

02:16 We see that a and bw are five map units apart, meaning that they are pretty close together.

02:23 So we can do that same process for the others...

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