Quick Frizzle Genetics Question

[PBAndAlice]

Working on a project about Frizzle chickens for a school Open House and don't wanna look like a moron in front of the whole town so I need some help.

I only have simple baseline knowledge of genetics so I don't understand the big words and I'm also getting a lot of mixed info.

This is what I think I know:
Regular feathers are dominant, and curly/frazzle feathers are also dominant, meaning that frizzle feathers are incompletely dominant and are a combination of regular and frazzle/curly.
Please correct me if the above is wrong. (Edited because I'm not sure if "heterozygous" is the proper word, since it's for dominant+recessive, and this is dominant+dominant but still 2 different alleles? I guess??)

This is what I am confused on:
If you  theoretically breed two frizzles together, what would you get? Is it always going to result in frazzles/curlies, or is it 25% frazzle, 50% frizzle, and 25% regular (my understanding)? Or something entirely different?

This is what else I am confused on: Am I overthinking this too much or is it way more complicated than I think?

Again I know barely anything about genetics so please explain like I'm 5. Thank you.

 

[PBAndAlice]

I did more research and I think I understand now. What I'm getting is that regular feathers and curly feathers are equally dominant over each other, resulting in frizzle being a phenotype/appearance of the two genes being mixed, NOT a seperate gene. Is that correct? Also I've seen a lot of people saying frizzle x frizzle = 25% regular, 25% curly, and 50% frizzle, so I'm going with that.
I think I'm kinda overthinking this, as I tend to do with my projects, but I'm at a point I'm confident enough that I'll just write this down, and if someone happens to correct me on Open House day, that's fine too. I'll distract everyone with the actual chicken so they don't look at my poster LOL.

 

[pipdzipdnreadytogo]

The frizzle gene, itself, is incompletely dominant. Smooth feathering is considered recessive to frizzling, not also dominant. As that is the case, we assign a capital letter to the dominant for frizzled feathering, F, and a lowercase letter to the recessive smooth feathering, f+, when we're referring to that particular trait. The plus sign tells you what the wildtype allele is, what the wild population would have for that particular gene, so that's smooth feathering in this case.

What incompletely dominant means is that in a gene pair, when one copy of the incompletely dominant gene is present, it gives a partial effect of the trait. So in this case that would be F/f+ for a frizzled individual. When two copies of that gene are present, it gives the full effect of the trait. In this case, F/F for frazzled or 'curly' individuals. Think of incomplete dominance as working in steps: smooth feathering (f+/f+) is smooth, of course, while frizzled feathers (F/f+) are curved but not extremely so, and frazzled feathers (F/F) are extremely curled to the point of being brittle.

As for inheritance, each bird has several pairs of chromosomes made up of all the genes they inherited, one half of each pair from each parent. That means that each gene comes in a pair, with the exception being in sexlinked genes, another topic entirely. In the case of frizzling, a frizzled individual has the pair F/f+ for frizzling, as discussed above. That individual can thus pass on either an F or an f+ from that gene pair to its offspring, the other half of that pair being supplied by the other parent. When you cross a male with F/f+ to a female with F/f+, since that gene pair is not of a sexlinked gene and so is inherited equally by all offspring, you have the chance that both parents will pass F to any particular chick, that the father will pass F and the mother will pass f+, that the father will pass f+ and the mother will pass F, or that both parents will pass f+. Dominants are put before recessives when writing gene pairs, so the possible outcomes of that crossing are F/F, F/f+, F/f+, and f+/f+. In other words, the odds of getting a chick with F/F is 1 of the 4 possibilities or 25%, the odds of getting f+/f+ is also 1 in 4 or 25%, and the odds of getting F/f+ is 2 in 4 or 50%.

For the record, in a specific gene pair, when both genes match, such as F/F or f+/f+, we refer to that individual as homozygous for that trait. When the pair is mismatched, as in F/f+, we refer to that individual as heterozygous for that trait. So yes, a frizzled individual is heterozygous for the frizzling gene!

I hope that clears some things up, but feel free to ask more questions if I've made anything less clear for you!

 

[PBAndAlice]

The frizzle gene, itself, is incompletely dominant. Smooth feathering is considered recessive to frizzling, not also dominant. As that is the case, we assign a capital letter to the dominant for frizzled feathering, F, and a lowercase letter to the recessive smooth feathering, f+, when we're referring to that particular trait. The plus sign tells you what the wildtype allele is, what the wild population would have for that particular gene, so that's smooth feathering in this case.

What incompletely dominant means is that in a gene pair, when one copy of the incompletely dominant gene is present, it gives a partial effect of the trait. So in this case that would be F/f+ for a frizzled individual. When two copies of that gene are present, it gives the full effect of the trait. In this case, F/F for frazzled or 'curly' individuals. Think of incomplete dominance as working in steps: smooth feathering (f+/f+) is smooth, of course, while frizzled feathers (F/f+) are curved but not extremely so, and frazzled feathers (F/F) are extremely curled to the point of being brittle.

As for inheritance, each bird has several pairs of chromosomes made up of all the genes they inherited, one half of each pair from each parent. That means that each gene comes in a pair, with the exception being in sexlinked genes, another topic entirely. In the case of frizzling, a frizzled individual has the pair F/f+ for frizzling, as discussed above. That individual can thus pass on either an F or an f+ from that gene pair to its offspring, the other half of that pair being supplied by the other parent. When you cross a male with F/f+ to a female with F/f+, since that gene pair is not of a sexlinked gene and so is inherited equally by all offspring, you have the chance that both parents will pass F to any particular chick, that the father will pass F and the mother will pass f+, that the father will pass f+ and the mother will pass F, or that both parents will pass f+. Dominants are put before recessives when writing gene pairs, so the possible outcomes of that crossing are F/F, F/f+, F/f+, and f+/f+. In other words, the odds of getting a chick with F/F is 1 of the 4 possibilities or 25%, the odds of getting f+/f+ is also 1 in 4 or 25%, and the odds of getting F/f+ is 2 in 4 or 50%.

For the record, in a specific gene pair, when both genes match, such as F/F or f+/f+, we refer to that individual as homozygous for that trait. When the pair is mismatched, as in F/f+, we refer to that individual as heterozygous for that trait. So yes, a frizzled individual is heterozygous for the frizzling gene!

I hope that clears some things up, but feel free to ask more questions if I've made anything less clear for you!

Thank you so much for this reply! I apologize for replying so late because I didn't get notified, and it was a busy night so I forgot to check back. It makes a lot more sense now, and I see that almost everything I got correct, except for the dominant and recessive part. Like I said, I was lost because of how many mixed answers I was seeing, I couldn't find a straight answer for which gene was dominant and which was recessive.
I assumed that calling Frizzle a "mix of the two genes" (appearance wise at least, or as a phenotype) made enough sense while still being partially factual, anyway. Luckily nobody at the open house knew that much about genetics (it was majority little kids anyway), so they probably didn't remember me calling the genes "equally dominant", especially with all the other projects that came after mine. Well, nobody except for my old Biology teacher, who I'll have to email an update to, lol. Thanks again for making it clearer

 

[SherrynBill]

Working on a project about Frizzle chickens for a school Open House and don't wanna look like a moron in front of the whole town so I need some help.

I only have simple baseline knowledge of genetics so I don't understand the big words and I'm also getting a lot of mixed info.

This is what I think I know:
Regular feathers are dominant, and curly/frazzle feathers are also dominant, meaning that frizzle feathers are incompletely dominant and are a combination of regular and frazzle/curly.
Please correct me if the above is wrong. (Edited because I'm not sure if "heterozygous" is the proper word, since it's for dominant+recessive, and this is dominant+dominant but still 2 different alleles? I guess??)

This is what I am confused on:
If you  theoretically breed two frizzles together, what would you get? Is it always going to result in frazzles/curlies, or is it 25% frazzle, 50% frizzle, and 25% regular (my understanding)? Or something entirely different?

This is what else I am confused on: Am I overthinking this too much or is it way more complicated than I think?

Again I know barely anything about genetics so please explain like I'm 5. Thank you.

Never mate a frizzle and frizzle together! They have multiple genetic problems or die before hatching.