00:01
For genetics, we have two different genes that are going to interact and determine the color of this particular species.
00:08
If both are dominant, we get a gooty colored.
00:15
If the first one is dominant, but not the second one, then we get black colored.
00:23
However, if the first one is not dominant, it does not matter what the second one is, there will be no color at all.
00:32
Do not pass go, do not collect $200, you just go straight to colorless.
00:40
Alright, in this case, we are going to look at a few different examples of how this can play out and what you would expect to see in certain lineages.
00:52
With this first example, we are starting with the knowledge of what the two parents are.
00:57
We know that one parent has only a dominant a and all the rest are recessive.
01:03
The second parent has two recessive a's and two dominant b's.
01:07
What would their offspring be? what would they look like? what are those ratios? well, good news is we can actually figure this out without having to do a whole big punnett square.
01:23
Because we can see that for the b alleles, because that's going to be easiest, one parent only has recessive alleles.
01:38
That means that they are only going to be able to pass on recessive alleles.
01:45
So all of the children, regardless of anything else, will get a recessive b allele from the first parent.
01:50
The second parent only has dominant b's, so all of the offspring have to get a dominant b from that parent.
02:01
The second parent has the same thing with a's.
02:04
They only have recessive, so all of their offspring have to get a recessive a from the second parent.
02:13
Now the only thing that's a little bit of a challenge is going to be the first parent who has one dominant a, one recessive.
02:20
But all that means is that there's a 50 % chance they can give their offspring a dominant a, and a 50 % chance they can give a recessive.
02:28
So their offspring have two options.
02:31
They can have all of this, you know, the recessive a, dominant b, recessive b, plus a dominant a.
02:40
Or they can give, they can get a recessive a from the first parent and still have all the rest.
02:47
And there's a 50 -50 shot of that.
02:53
And that's the whole thing.
02:54
We've determined what the offspring will look like from these two parents.
02:58
And most of your questions here are like that you don't actually have to do punnett squares to figure it out, if you just stop and take it one gene at a time.
03:07
So we're going to look at another example.
03:12
Here we start with where we know one parent's genotype, which is only recessive alleles, and we know the f1 generation, where 50 % have a gooty color, where they have at least one dominant allele for each, and half of them are colorless, where they have to have at least two recessive a alleles.
03:48
Based on that knowledge, we can determine almost entirely what this other parent's genotype is.
03:57
So we just stop and take it one gene at a time.
04:02
Let's start with a's.
04:07
For the offspring, we can see that half of the offspring need to receive a dominant a.
04:17
So there has to be a dominant a somewhere...
