Post by laurcat on Jan 24, 2013 19:35:23 GMT -5
I got bored so I decided to teach random lessons on here. Feel free to learn- or to make your dolls learn. This is about genetics and Punnett squares, so if you don't know what all that stuff is about, I try to explain. You can still ask for help, though. I want to do a second genetics lesson that gets into more complicated scenarios, but I needed to start off with the basics.
In New Germany, a country no one knows about, so don’t bother looking it up, humans have peculiar traits for hair. But for now, we will look at the more familiar ones. There are two hairstyles- straight and curly. I’ll take a moment to let you recover from the shock of the strangeness. (Curly hair, what the flibbenhagen? [New German word, don’t bother looking it up.]) Now, straight hair is dominant to curly hair. Examine the genotypes below:
-SS=Straight hair, homozygous dominant
-Ss=Straight hair, heterozygous
-ss=Curly hair, homozygous recessive
If you have no idea what that means: (If you know, just skip this.)
The ‘s’s represent alleles. You have usually two alleles for each trait- they determine what trait you’ll actually have. Alleles are expressed in capital and lowercase letters. Capital letters represent what we call dominant alleles. Lowercase letters are what we call recessive. Dominant traits mask, or cover up, recessive traits. If you were heterozygous for straight hair, your genotype, or allele combination, would be ‘Ss’. You have one dominant allele and one recessive allele, but since the dominant allele masks the recessive, your phenotype will be straight hair. Your phenotype is basically the result. Your genotype would be ‘Ss’, and your phenotype would be straight hair. ‘SS’ has two alleles for straight hair, so the result is obvious, but how do you get curly hair? Since it is recessive, you can only get the trait if you have two alleles for it. If you have at least one dominant allele, it will get in the way and you won’t show the recessive trait. If your phenotype is ‘ss’, you are recessive homozygous, and will have curly hair. If you are homozygous, you have two identical alleles. (SS, ss.) If you have two dominant alleles, you are homozygous dominant. If you have to recessive alleles, you're homozygous recessive. If you are heterozygous, you have two different alleles. (Ss.) Since there is a dominant trait that will mask the recessive, someone who is heterozygous will show the dominant trait.
Now, I will tell you young childrenhagens a story. (Yay, story time!)
Bardenhagen Flibbons was proud of his straight hair, and believed straight hair to be superior to curly. He married Trishahagen Whethersteps, a woman with straight hair. He had four children, and expected them all to have straight hair. However, all hagen broke loose when his fourth child possessed curly hair. What the hagen? Bardenhagen figured the hospital must have given him the wrong baby- That couldn’t be his son! Or could it? Solve the Punnett square to find out. (You can draw it on a sheet of paper or somethinghagen.)
Bardenhagen’s genotype: Ss
Trishahagen’s genotype: Ss
If you don’t know what to do:
Put one capital S on top of the box in the top left hand corner, then put a lowercase s over the box in the top right hand corner. Put another capital S on the side of the box in the top left hand corner, then another lowercase s next to the box in the bottom left hand corner. You will now have ‘Ss’ on top of the boxes representing one parent, and ‘Ss’ on the side representing another parent. Now, match up both alleles from one parent to both alleles of the other, creating four combinations of alleles. For example, the box in the bottom left hand corner would share the allele ‘S’ from the parent on top, and ‘s’ from the parent on the side. (These two alleles are the ones lining up at that box.) This would make the offspring’s genotype ‘Ss’. (Common practice is to write the dominant allele, or capital letter, first.) And remember, the dominant allele masks the recessive allele, so this offspring will have straight hair.)
The end result should look something like this-
See that the possible genotypes are SS, Ss, and-what’s this?- ss.
There is-
25% chance of having homozygous offspring with straight hair
50% chance of having heterozygous offspring with straight hair
25% chance of having homozygous offspring with curly hair
So, sorry Bardenhagen, but yes, that is your son. Since both he and his wife had one recessive allele for curly hair, producing offspring with curly hair is possible. When each of those lowercase ‘s’s matched up, they created the homozygous recessive combination for curly hair. In other words, s+s=ss.
Now, let’s all take a moment to tell Bardenhagen to get off his high horse. Straight hair isn’t all that and a bag of chips. What a hagenflipper…
In New Germany, a country no one knows about, so don’t bother looking it up, humans have peculiar traits for hair. But for now, we will look at the more familiar ones. There are two hairstyles- straight and curly. I’ll take a moment to let you recover from the shock of the strangeness. (Curly hair, what the flibbenhagen? [New German word, don’t bother looking it up.]) Now, straight hair is dominant to curly hair. Examine the genotypes below:
-SS=Straight hair, homozygous dominant
-Ss=Straight hair, heterozygous
-ss=Curly hair, homozygous recessive
If you have no idea what that means: (If you know, just skip this.)
The ‘s’s represent alleles. You have usually two alleles for each trait- they determine what trait you’ll actually have. Alleles are expressed in capital and lowercase letters. Capital letters represent what we call dominant alleles. Lowercase letters are what we call recessive. Dominant traits mask, or cover up, recessive traits. If you were heterozygous for straight hair, your genotype, or allele combination, would be ‘Ss’. You have one dominant allele and one recessive allele, but since the dominant allele masks the recessive, your phenotype will be straight hair. Your phenotype is basically the result. Your genotype would be ‘Ss’, and your phenotype would be straight hair. ‘SS’ has two alleles for straight hair, so the result is obvious, but how do you get curly hair? Since it is recessive, you can only get the trait if you have two alleles for it. If you have at least one dominant allele, it will get in the way and you won’t show the recessive trait. If your phenotype is ‘ss’, you are recessive homozygous, and will have curly hair. If you are homozygous, you have two identical alleles. (SS, ss.) If you have two dominant alleles, you are homozygous dominant. If you have to recessive alleles, you're homozygous recessive. If you are heterozygous, you have two different alleles. (Ss.) Since there is a dominant trait that will mask the recessive, someone who is heterozygous will show the dominant trait.
Now, I will tell you young childrenhagens a story. (Yay, story time!)
Bardenhagen Flibbons was proud of his straight hair, and believed straight hair to be superior to curly. He married Trishahagen Whethersteps, a woman with straight hair. He had four children, and expected them all to have straight hair. However, all hagen broke loose when his fourth child possessed curly hair. What the hagen? Bardenhagen figured the hospital must have given him the wrong baby- That couldn’t be his son! Or could it? Solve the Punnett square to find out. (You can draw it on a sheet of paper or somethinghagen.)
Bardenhagen’s genotype: Ss
Trishahagen’s genotype: Ss
If you don’t know what to do:
Put one capital S on top of the box in the top left hand corner, then put a lowercase s over the box in the top right hand corner. Put another capital S on the side of the box in the top left hand corner, then another lowercase s next to the box in the bottom left hand corner. You will now have ‘Ss’ on top of the boxes representing one parent, and ‘Ss’ on the side representing another parent. Now, match up both alleles from one parent to both alleles of the other, creating four combinations of alleles. For example, the box in the bottom left hand corner would share the allele ‘S’ from the parent on top, and ‘s’ from the parent on the side. (These two alleles are the ones lining up at that box.) This would make the offspring’s genotype ‘Ss’. (Common practice is to write the dominant allele, or capital letter, first.) And remember, the dominant allele masks the recessive allele, so this offspring will have straight hair.)
The end result should look something like this-
See that the possible genotypes are SS, Ss, and-what’s this?- ss.
There is-
25% chance of having homozygous offspring with straight hair
50% chance of having heterozygous offspring with straight hair
25% chance of having homozygous offspring with curly hair
So, sorry Bardenhagen, but yes, that is your son. Since both he and his wife had one recessive allele for curly hair, producing offspring with curly hair is possible. When each of those lowercase ‘s’s matched up, they created the homozygous recessive combination for curly hair. In other words, s+s=ss.
Now, let’s all take a moment to tell Bardenhagen to get off his high horse. Straight hair isn’t all that and a bag of chips. What a hagenflipper…
It's confusing, but I love it 
