00:01
Okay, so in this question, we are trying to figure out whether these mutations that were shown are on the same or on different genes.
00:10
And that is the whole premise of what a complementation test is.
00:14
And so a matrix is just a way of showing whether complementation occurred or whether it did not occur.
00:20
So in terms of that terminology, complementation means that the two mutations together were on, the two mutations did complement each other means that they're different genes.
00:30
Whereas if the two mutations don't complement each other, they're on the same gene.
00:34
And in a matrix, a plus sign represents that complementation did occur, whereas a minus sign indicates that complementation did not occur.
00:43
So we have to look at each of the mutations individually.
00:47
So we see that mutant one crossed against all of the others got a positive sign, meaning that there was complementation, meaning that mutation number one is on a different gene from all of the others.
01:00
If we look at mutant 2, we see that there's a minus sign on 2 and 4.
01:04
So because there's a minus sign on mutant 4, that means that mutation 2 and mutation 4 don't complement each other, meaning that they're on the same gene.
01:15
However, if you look at the cross of 2 and 3 and 2 and 5, there's a positive sign, meaning that these mutations did complement each other.
01:23
So that suggests that the progeny were the prototrophs instead of the autotrophes.
01:27
So we know that 3 and 5 must be on a different gene than 2.
01:33
So then we look at number 3.
01:35
3, again, we get the same proof.
01:37
3, there's a minus on the 3 and on the 5.
01:39
So because there's a minus on the 5, again, this suggests that 3 and 5 don't complement each other, meaning that they're on the same gene.
01:48
4 has only a minus with itself...