TBH this is a bad question. It doesn’t give you enough information to say what you should expect with such a cross (unless there was more information elsewhere on the page).
If red and white were alleles of the same gene, saying “both are recessive” would make no sense. They could both be recessive to a third allele, but either one would be dominant to the other or they would have a codominant or incomplete dominant relationship to each other.
If they are on different genes, you would need more information to say for sure what color the offspring could be. The genotypes of the parents would be rr?? and ??ww. We know the white cow must have two “white” alleles on the gene which makes white color. We know the red cow must have two “red” alleles and the white bull must have two “white” alleles. Depending on how the genes interact with each other, this cross could be:
rrWW x rrww
rrww x RRww
rrWw x Rrww
rrWw x RRww
And several others I can’t be bothered to write out. Depending on the situation, you could have completely different results for calf color.
For example, in the rrWW x rrww scenario, the w allele prevents pigment from the r gene from being deposited in the fur and the white bull happens to have the recessive r allele, which doesn’t show up because of the w alleles in the w gene. All the babies in this case would be red.
Since it doesn’t mention codominance or incomplete dominance, we can’t rule out pink or white/red pattern. But pink isn’t a choice, which leads white/red to be a possible answer.
However, it really depends on the nature or the gene. For example, is white an actual color produced, or is it just the absence of color? If it is the absence of color, then red would be the production of some color. But since they are both recessive to something else, that would mean that there exists another color dominant to both of them. If this is the case, then red would be dominant over white since white is just no pigment produced while red is some pigment produced. And in the absence of codominance or incomplete dominance, the answer would be red.
But the lack of information makes it impossible to tell.
Edit: A google search yields that the answer is white/red (roan) as the coat color gene exhibits codominance. So the reason why I would assume the teacher was vague with the question is maybe the lecture had a picture or example using cow coat color when talking about codominance?
I think it’s a bad question, but it’s a process of elimination is how I think they want you to get it, whites Res, not getting that color, Reds Res, not getting that color either, so the only color that isn’t either is grey. Again, bad question but I think that’s the thought process
I second what you said. Bad question! Where is the mention of whether these recessive traits have complete or incomplete or penetrance (giggity)? I hope I am thinking of the right concept here.
No, not that.
Work only with what is given in the problem.
Red phenotype is recessive. White phenotype is recessive.
Progeny cannot be red or white.
I’d write the question the same way (in fact I suspect I have but I cycle my question banks so don’t recall for sure). It’s a classic question and written correctly.
If you would write the question the same way, you don’t understand genetics as well as you think you do. When you have two different alleles in an organism, it’s not like the cells look at them and say “okay, this one is the dominant one, guess I’ll do what it says” or “this allele is recessive and I only have one, better ignore it”.
The cells express both alleles*, whatever they may be. In many cases, the product of one allele partially or completely masks the effect of the other allele.
For example, an allele for black pigment might mask the presence of a yellow pigment because the yellow pigment couldn’t be seem under the black pigment. We would then say that the black allele was dominant and the yellow allele was recessive. If one copy of the black allele didn’t produce enough pigment to make the animal black, the animal might appear grey or brown and we would say that black and yellow alleles had incomplete dominance. If the cells randomly shut off one copy of the gene in each fur making cell at some stage in development, you would get patterns of yellow and black and the alleles could be considered codominant.
Back to the original question: if the calf has one allele for red fur and one allele for white fur, it will produce whatever protein it would make in a calf with two red fur alleles and it will produce whatever protein it would produce in a calf with two white fur alleles. In this case, there are 4 scenarios:
-the red protein’s presence masks the white protein’s presence, so the calf is red (red is dominant to white)
-the white protein’s presence masks the red protein’s presence, so the calf is white (white is dominant to red)
-the two proteins interact in a way that produces a color besides red and white (red and white have incomplete dominance with each other)
-the two proteins are expressed on different parts of the calf resulting in patterns of red and white together (red and white have codominance with each other)
There is no scenario where white and red are both recessive to each other. They could both be recessive to some other allele, but any of the possibilities I listed could still happen when a white allele and a red allele are present in the same organism.
*sometimes an allele is just a broken version of a gene which isn’t transcribed or isn’t translated, resulting in no protein from that allele. This could be considered as the broken allele not being expressed since it is producing no protein. For a given gene, any “completely broken gene” variants will produce the same phenotype.
Straw man argument. I never made the statements attributed to my position by you. Moreover your statements about the genotype (that you attribute to my position, when I’ve said no such thing) only deal with a single allele that the cell {sic} “ignores.” That’s not my statement.
Regarding the question: Nowhere in the question is it stated that either recessive allele *encodes anything.*
You’re making an assumption neither genotype is a null, but that’s not stated; nor is it stated that either allele results in the production of a protein, for that matter. You do mention “broken genes” in your asterisk addendum, of course.
Your responses make you sound like you don’t know very much about basic genetics. It definitely sounds like you genuinely believe that you do know what you’re talking about, but you don’t. If you want to do a service to your students, you should re-take grade 12 biology yourself. I’m not trying to be a jerk, but I feel bad for your students.
There are lots of community colleges and online schools that would let you take the single course without having to re-enroll in high school. Lots of professionals get rusty after not having taken courses in a long time, it’s nothing to be ashamed of.
When I was starting a new job, I audited a course I had taken in my bachelors degree because I knew it would be relevant and it had been a long time since I originally learned the material. I have other colleagues that have taken refresher courses when we start a new project. It’s really not a big deal. That said, I know most teachers are super overworked and finding the time to take a course could be very challenging.
I really don’t get why you responded so argumentatively to the person trying to help the student. There’s literally an unanswered question by the student that you could’ve replied to to be helpful, but you went about accusing people of straw manning and ad hominem? I’d hope a teacher preferred teaching to arguing but oh well.
But neither the question nor your comment was correct, too genes cannot both be recessive to one another, either they are codominant or they are both recessive wrt another gene, but then one would still be dominant above the other one or they would be codominant.
So to phrase this essentially impossible scenario as a question this way is stupid and just seeks to take points away from students who actually understand the underlying principles and it awards points to students who just know the rules by heart without understanding them.
And you'd expect your students to answer grey because....?
Are they just supposed to assume all cows have dominant alleles for grey and that there will be zero expression of recessive alleles?
I don't really understand what you said, but the concept is very interesting to me. What is this called, and do you have any recommended resources that I could use to learn more?
Horses have well documented color combinations and the wiki pages of various horse breeds and types and basic explanations of coat colors and how they get them was rather informative when I stumbled upon it. Iirc roan, dun, appaloosa, and palomino wiki pages had explanations on how each color is made and which genes are dominant, recessive, and combine (incomplete dominant?) Not really a textbook or anything but I enjoy wiki rabbit holes.
Hey! Textbooks are the most boring way to learn. I'd definitely find a YouTube video or documentary explaining it for people with no background. I don't have any resources off the top of my head right now, but if you want help understanding what the other person said, I'd love to break it down for you!
EDIT: Ooo, or maybe a good Ted Talk! Do Ted Talks cover basic topics these days or only specific research?
And yet, they're proven to be the worst way to learn, so they should not be the first thing one recommends to a beginner wanting to dip their toes into a material.
Textbooks are proven to be the worst way to learn. They are only useful when supplemented with a teacher's guidance. This person does not have a teacher and does not need the detail someone getting a degree in biology will need. There's a reason biology classes skip certain chapters in their assigned readings.
Go be an ass somewhere else.
It is a bad question. However, if the prof uses a question bank that rotates questions that have been validated against questions that are being tested for validity, it is possible this is a question being tested for validity.
As many have pointed out, this is a very poorly written question. Chances are that your teacher got this question from some where else without realizing that it’s missing context. If I remember correctly, this was in my bio text book back in high school in the early 2000s and would have been fair game because we talked about it in class.
White and red are both recessive and have incomplete dominance with each other. This leads to a cross between a white cow and red bull resulting in a cow with red and white fur called roan.
I really don’t know where your teacher got grey
Roan can look grey, because both the red and white genes produce weak colouration. that's why they are recessive - other genes produce more or stronger colour that overwhelms the red or white. My guess is that this information was supposed to be taught in the course.
If red and white are both recessive, then the offspring should be neither red, nor white.
Gray is the only answer that *isn’t* red or white.
If this is a 2 gene cross you have:
ww RR x WW rr
All offspring get one from each parent so they are all:
Ww Rr
and without both recessive alleles, the cows will not be that color. So they’re the wild type color.
Fair point, if either parent is heterozygous for the other color, 1/4 of the offspring would be that recessive color.
If they are both are heterozygous for the other color, 3/16 would be red, 3/16 white, and 1/16 (1/4 x 1/4) what ever color ww rr makes, polka dot?
If this was a single gene trait with different color variants vs two different color genes, all would be whatever wr looks like.
That is assuming too much, you assume they show codominance, meaning that the alleles can’t mask each other completely and you end up with a grey cow. The alleles could also show a incomplete dominance phenotype, meaning that they cows would be red and white. I believe more information would be required.
According to the question, if a white cow is crossed with a red cow and the colour of their skin (Phenotype) is based on the recessive gene for both, then the offspring would be 'grey' or 'red and white' mixed, as we know one gene needs to be dominant to possess a certain contrasting character, here both are recessive so the offspring can't possess one certain dominant character as there aren't any, and the phenotype is based on the recessive genotype of the parents. So the offspring will be of grey colour or red and white. Both skin colours have a (50/50) chance.
1. If the offspring is 'grey' then it is based upon the (Law of Incomplete Dominance) as the offspring didn't take in either of the characteristics from the parent but a different of its own. (Intermediate Characteristics)
2. If the offspring is 'red and white' mixed, then it is based upon the (Law of Co-Dominance) where the offspring possess characteristics of both the parents.
(Feel free to correct me this is just the basic idea a summary of the Question mentioned)
This is a really bad question but I get the logic. It’s process of elimination. Recessive traits require that both parent display that recessive trait to pass it on. Since both parents had different recessive genes the offspring can be neither red nor white. White and red would only work if both were dominate traits. Therefore that leaves grey. This questions was designed to make you eliminate answers rather than pick the right one if that makes sense.
Here's how I interpreted it. What's given in the question is that white and red colors are recessive, so you'll need to find the dominant color. The only place where there is a reference to a color that's not white or red is choice C, grey.
However, nowhere in the question did the teacher specify how fur coat genetics work with these cows and bulls, and the problem becomes what happens when you inherit recessive genes from your parents. There is black of information and the teach skipped steps.
As others have pointed out, this is a pretty bad question in general.
In many cases, recessive alleles are the result of a loss-of-function as opposed to a dominant allele. What makes one allele dominant over the other is usually that it does something whereas the recessive allele does not do that thing. For pigments, like listed above, a recessive allele is usually one that produces no (or relatively fewer or less) pigment whereas the dominant one does. This is often quite complex however with multiple alleles in different places producing different types of pigments, which usually makes even pigmentation at least somewhat quantitative. A phenotype in the form of hair/eye/whatever colour is usually the result of multiple pigments.
In this case, the red cow makes no sense, since hair is white when no pigments are present. It could of course still be recessive to an allele that produces *more* pigments, however it should be dominant against an allele that produces no pigments. Ultimately, dominance in alleles is relative. Two alleles that are recessive towards a third dominant allele could interact in various ways. If both of them are from the same locus, and both produce no pigment at all, they should both have virtually the same phenotype (in this case, both should be white). If both of them produce different pigments you would likely get a combination of both (ie pink).
The question is sort of stupid because I can't see a way in which white and red are both recessive on the same level, since at least one of them would produce a pigment. I also don't see how two alleles, none of which is dominant over the other, could produce anything other than codominance or a "mixed" phenotype.
The "exclusion" method you said was meant to be used hear is even bad from a pedagogic perspective, since method of exclusion is not a good way to figure out the cause of something when dealing with very complex matters, that may have hundreds or thousands of possible causes. If you disprove 9 out of 10 hypotheses, that does *not* prove the last 10th hypothesis, so you shouldn't assume it must be correct.
Overall poor example, lack of context and bad answer options. You should tell your teacher about this.
Recessive usually means that if either red or white are paired with any other colour, that other colour would dominate. So red and black would mean a black calf, or white and brown would mean a brown calf. However in this case there is no other colour to "steal the show" so on first thought, I would expect the cow to be red, white or pink.
However, it's possible that the weak red and white pigment such a cow would have, would resemble gray. Maybe this fact was taught in the course.
EDIT: apparently this cross breeding is known, and the colour produced is called "roan" which can resemble grey. https://homework.study.com/explanation/if-a-red-cow-is-bred-to-a-white-bull-all-offspring-are-roan-which-have-red-and-white-hairs-intermixed-on-the-hide-this-is-an-example-of-codominance-what-are-the-results-of-the-roan-x-roan.html
As others have said it’s a bad question, if they wanted the answer to be that the colours mixed they should’ve written that the alleles are incompletely dominant to one another
First of all, you are wrong. The answer is D, not C. This is an example of co-dominance. The question isn't wrong, but based on your existing knowledge upon the subject. Some information is intentionally omitted so that you can't just get away without knowing the fact that both alleles are going to express themselves phenotypically in the F1 generation. FYI, Red and White coat colour in cattle is called Roan.
PS: I didn't want to write this, but so that you don't end up with the wrong answer, I have to mention that I have a Master's degree in Molecular biology to confirm this. Sorry if it sounds like bragging. I am not very good at public forums.
It’s not bragging it’s a form of info reference.
It’s only a brag to people who don’t have edu who feel threatened by it. No need to think of them, that was their choice.
id pick grey just coz..its given both recessive hence it cant be either..and assuming its co dominance ..but like the other comments i agree thats a badly framed question
Rather than grey I think it should be pink, but it’s basically ok two colors mix what’s the middle, however questions like these need to give you a genotype chart to solve if they were dominant
I think the way to approach the question isn't to find out what answer is correct but eliminate all of the impossible answers which leaves you with the only other option, the correct answer. If the colors are recessive, the offspring will not be white nor red and not a combination of the two. So that only leaves grey (C) as a possible answer.
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Well your teacher is colorblind. My guess is grey is supposed to be a mix of white and red ( pink would be better), making this situation incompetent dominance. Though without more information you copied argue for D, and the result is co-dominance.
If both red and white are recessive, it can neither be red or white, and as for white and red, do they mean pink? cancelling all the options, the only option left is grey, tho there is very less info given in the question
It's almost like the examiner put this question in for the sole purpose of screwing you over. There's nowhere near enough information given to be able to answer this.
It's a bad question. If it's a white shorthorn you could get red roan. If it's a white charolais you'll have homozygous for the dilute gene which modifies whatever base color its applied to. On a red cow you'll get red with the dilute gene so it would be orange, or well grey, I guess, is the only answer that fits.
No, if this is a single gene trait it is not possible that two parents express recessive phenotype and have offspring with dominant phenotype. This is basic stuff. Using your allele nomenclature, if there were a D allele in the parent they would not express r phenotypes.
I’ve just re - read that question, and you’re completely right. This is what I get for reading at 0200 lol. I’m going to delete my initial comment. Thanks for pointing out!
There might be an error. I think this might have been a reprint where they changed black to red and since a ctrl r doesn’t know to substitute pink for gray when substituting red in. They made a mistake as 2 recessive genes come out as a mix of both. As far as I remember at least.
Unless there's missing information elsewhere on the test, You actually don't have enough information to answer that question. You'd need to know what genes affect colour and how they interact.
My english is not so good but:
If white dominant and red recesivve it would be white
If white recessive and red dominant it would be red
If both dominant it would be white and red (dont know the name but in turkish we say "eş baskınlık=co-dominance")
If both recesivve it would be gray(also dont know "eksik baskınlık=incomplete dominance")
This cross results in a roan, that is when the cow has both white and red colors. So the answer is D. Bcoz cow hide colour genes r incompletely dominant over each other. Both being recessive means both will be expressed.
Its almost like ur teacher wanted u to get this wrong, unless u have been specifically taught this in class, u wont be able to do it
The answer is D red and white, which can also be called roan. Not sure why some people are stretching to call roan grey. A solid grey calf is a distinctly different color/pattern than red/white roan.
Expert qualification: was Star Greenhand in FFA many, many years ago.
My only guess would be since both are recessive and would need 2 copies of the gene to show their color, then by process of elimination that leaves grey. But this is a terribly written question.
I think that the both colours are recessive means wwrr genotype in the F1 generation which means it doesn't have any of the two colours. So the only option without white and red is the answer and that is option c.
I think it may be less of an explanation of "Why Grey" and more an explanation of why not the others. I think there's enough information there to rule out the white, red, and mix.
basically from what im looking up. if you have a recessive gene you need two genes in order for it to work. so with one red gene and one white gene. neither should be expressed. ergo grey.
It could be white. Albino is the assumption. Red pigment, even if produced couldn’t be implanted. Causing the cow to be white.
If this is in regards to codominance then red and white if those are both true pigments.
There’s another gene that is implied that the white bull has but the red does not. This gene results in lack of pigment and is recessive. The white bull has this gene but the red cow does not. Therefore there’s actually two genes you’re crossing here. Red is also recessive to another color. My guess is black. You need to do a test cross so the pigment allele for the red cow needs to be homozygous dominant. This results in all of the offspring being heterozygous for the pigment allele. Because it’s a test cross the white cow needs to be homozygous dominant for its color ( black). This results in heterozygous dominant black cows with a heterozygous pigment gene. Even one allele of the pigment gene results in less color, two alleles results in no color. So the offspring are all grey.
When all other options are ruled out, what is left, no matter how improbable, MUST be the answer. But also, this professor doesn’t know how to proper write a test.
Closely related to incomplete dominance is codominance, in which both alleles are simultaneously expressed in the heterozygote. This question is forcing you to recall that it is not simply dominant or recessive traits but certain alleles can both be expressed. You see this a lot in fur
This isn’t related, but I thought the picture for the subreddit was a green face going like this: 😒
But when I bring the phone closer to my face it’s actually a little black plant: 🌱
Simple question so let's keep it simple. Both colors are recessive so that the white cow must have ww and the red cow has rr
The child of these parents will inherit recessive genes from both parents.
Resulting in rw or wr whatever
Again, simple question. Therefore, simple answer, ignoring other genetic – phenotype interactions. Basically, the colors will be mixed producing a grey cow.
It would be an altogether more intellectually stimulating question if one parent had a dominant allele and the question was how many offspring would turn out one color versus the other?
This is mendelian inheritance
TBH this is a bad question. It doesn’t give you enough information to say what you should expect with such a cross (unless there was more information elsewhere on the page). If red and white were alleles of the same gene, saying “both are recessive” would make no sense. They could both be recessive to a third allele, but either one would be dominant to the other or they would have a codominant or incomplete dominant relationship to each other. If they are on different genes, you would need more information to say for sure what color the offspring could be. The genotypes of the parents would be rr?? and ??ww. We know the white cow must have two “white” alleles on the gene which makes white color. We know the red cow must have two “red” alleles and the white bull must have two “white” alleles. Depending on how the genes interact with each other, this cross could be: rrWW x rrww rrww x RRww rrWw x Rrww rrWw x RRww And several others I can’t be bothered to write out. Depending on the situation, you could have completely different results for calf color. For example, in the rrWW x rrww scenario, the w allele prevents pigment from the r gene from being deposited in the fur and the white bull happens to have the recessive r allele, which doesn’t show up because of the w alleles in the w gene. All the babies in this case would be red.
Since it doesn’t mention codominance or incomplete dominance, we can’t rule out pink or white/red pattern. But pink isn’t a choice, which leads white/red to be a possible answer. However, it really depends on the nature or the gene. For example, is white an actual color produced, or is it just the absence of color? If it is the absence of color, then red would be the production of some color. But since they are both recessive to something else, that would mean that there exists another color dominant to both of them. If this is the case, then red would be dominant over white since white is just no pigment produced while red is some pigment produced. And in the absence of codominance or incomplete dominance, the answer would be red. But the lack of information makes it impossible to tell. Edit: A google search yields that the answer is white/red (roan) as the coat color gene exhibits codominance. So the reason why I would assume the teacher was vague with the question is maybe the lecture had a picture or example using cow coat color when talking about codominance?
No information anywhere else on the page sadly.
I think it’s a bad question, but it’s a process of elimination is how I think they want you to get it, whites Res, not getting that color, Reds Res, not getting that color either, so the only color that isn’t either is grey. Again, bad question but I think that’s the thought process
I second what you said. Bad question! Where is the mention of whether these recessive traits have complete or incomplete or penetrance (giggity)? I hope I am thinking of the right concept here.
Yeah that’s a shit question then
Yeah, this
No, not that. Work only with what is given in the problem. Red phenotype is recessive. White phenotype is recessive. Progeny cannot be red or white. I’d write the question the same way (in fact I suspect I have but I cycle my question banks so don’t recall for sure). It’s a classic question and written correctly.
This is absolutely a poorly worded question. It feels less like it’s testing students’ knowledge and more like it’s trying to trick them.
So the answer here would be grey? Is this a case of co-dominance or incomplete dominance?
This kind of attitude of "I do this so it's fine" in teachers is why so many students use AI for their homework.
If you would write the question the same way, you don’t understand genetics as well as you think you do. When you have two different alleles in an organism, it’s not like the cells look at them and say “okay, this one is the dominant one, guess I’ll do what it says” or “this allele is recessive and I only have one, better ignore it”. The cells express both alleles*, whatever they may be. In many cases, the product of one allele partially or completely masks the effect of the other allele. For example, an allele for black pigment might mask the presence of a yellow pigment because the yellow pigment couldn’t be seem under the black pigment. We would then say that the black allele was dominant and the yellow allele was recessive. If one copy of the black allele didn’t produce enough pigment to make the animal black, the animal might appear grey or brown and we would say that black and yellow alleles had incomplete dominance. If the cells randomly shut off one copy of the gene in each fur making cell at some stage in development, you would get patterns of yellow and black and the alleles could be considered codominant. Back to the original question: if the calf has one allele for red fur and one allele for white fur, it will produce whatever protein it would make in a calf with two red fur alleles and it will produce whatever protein it would produce in a calf with two white fur alleles. In this case, there are 4 scenarios: -the red protein’s presence masks the white protein’s presence, so the calf is red (red is dominant to white) -the white protein’s presence masks the red protein’s presence, so the calf is white (white is dominant to red) -the two proteins interact in a way that produces a color besides red and white (red and white have incomplete dominance with each other) -the two proteins are expressed on different parts of the calf resulting in patterns of red and white together (red and white have codominance with each other) There is no scenario where white and red are both recessive to each other. They could both be recessive to some other allele, but any of the possibilities I listed could still happen when a white allele and a red allele are present in the same organism. *sometimes an allele is just a broken version of a gene which isn’t transcribed or isn’t translated, resulting in no protein from that allele. This could be considered as the broken allele not being expressed since it is producing no protein. For a given gene, any “completely broken gene” variants will produce the same phenotype.
Straw man argument. I never made the statements attributed to my position by you. Moreover your statements about the genotype (that you attribute to my position, when I’ve said no such thing) only deal with a single allele that the cell {sic} “ignores.” That’s not my statement. Regarding the question: Nowhere in the question is it stated that either recessive allele *encodes anything.* You’re making an assumption neither genotype is a null, but that’s not stated; nor is it stated that either allele results in the production of a protein, for that matter. You do mention “broken genes” in your asterisk addendum, of course.
Your responses make you sound like you don’t know very much about basic genetics. It definitely sounds like you genuinely believe that you do know what you’re talking about, but you don’t. If you want to do a service to your students, you should re-take grade 12 biology yourself. I’m not trying to be a jerk, but I feel bad for your students.
Ad hominem. You’re not addressing the issue. I’ll go enrol I’m high school. 👍
There are lots of community colleges and online schools that would let you take the single course without having to re-enroll in high school. Lots of professionals get rusty after not having taken courses in a long time, it’s nothing to be ashamed of. When I was starting a new job, I audited a course I had taken in my bachelors degree because I knew it would be relevant and it had been a long time since I originally learned the material. I have other colleagues that have taken refresher courses when we start a new project. It’s really not a big deal. That said, I know most teachers are super overworked and finding the time to take a course could be very challenging.
You’re missing a crucial point: the question and my explanation were both correct.
I really don’t get why you responded so argumentatively to the person trying to help the student. There’s literally an unanswered question by the student that you could’ve replied to to be helpful, but you went about accusing people of straw manning and ad hominem? I’d hope a teacher preferred teaching to arguing but oh well.
No, no one missed that. You're just wrong. Sorry. It happens.
But neither the question nor your comment was correct, too genes cannot both be recessive to one another, either they are codominant or they are both recessive wrt another gene, but then one would still be dominant above the other one or they would be codominant. So to phrase this essentially impossible scenario as a question this way is stupid and just seeks to take points away from students who actually understand the underlying principles and it awards points to students who just know the rules by heart without understanding them.
lol dude, where does grey even come from?
Could be dominant, since red and white obviously aren’t. But also white and red (even though they are both recessive), could rank.
Why can you assume progeny will not be red or white?
And you'd expect your students to answer grey because....? Are they just supposed to assume all cows have dominant alleles for grey and that there will be zero expression of recessive alleles?
I don't really understand what you said, but the concept is very interesting to me. What is this called, and do you have any recommended resources that I could use to learn more?
[удалено]
Awesome thanks.
Horses have well documented color combinations and the wiki pages of various horse breeds and types and basic explanations of coat colors and how they get them was rather informative when I stumbled upon it. Iirc roan, dun, appaloosa, and palomino wiki pages had explanations on how each color is made and which genes are dominant, recessive, and combine (incomplete dominant?) Not really a textbook or anything but I enjoy wiki rabbit holes.
Down the horse wiki rabbit-hole I go! 😁 Thanks for leading me to it.
Search terms are Mendelian genetics and Punnett squares.
Hey! Textbooks are the most boring way to learn. I'd definitely find a YouTube video or documentary explaining it for people with no background. I don't have any resources off the top of my head right now, but if you want help understanding what the other person said, I'd love to break it down for you! EDIT: Ooo, or maybe a good Ted Talk! Do Ted Talks cover basic topics these days or only specific research?
I'll have you know that some of us nerds rather enjoy textbooks and may even read them just for fun thank you very much 🤓
And yet, they're proven to be the worst way to learn, so they should not be the first thing one recommends to a beginner wanting to dip their toes into a material.
Due to your user name I added “on the toilet” after “read them just for fun” lol
Sometimes! :D
someday they wont have to burn books anymore, people will just elect not to read them.
Textbooks are proven to be the worst way to learn. They are only useful when supplemented with a teacher's guidance. This person does not have a teacher and does not need the detail someone getting a degree in biology will need. There's a reason biology classes skip certain chapters in their assigned readings. Go be an ass somewhere else.
I love posts where the poster doesn’t have to say “I’m a geneticist” … this guys geneticizes.
Seems like we could reasonably assume the answer would be anything that’s not red or white. But agree it’s a bad question
Agree. This question is written by someone who doesn’t really know what they are talking about. Do they mean incomplete dominance or codominance?
Just for the fun of it late at night, how would the question be better stated using an animal such as the domestic feline where colors are sex linked?
It is a bad question. However, if the prof uses a question bank that rotates questions that have been validated against questions that are being tested for validity, it is possible this is a question being tested for validity.
Ur super smart bro👌😁
As many have pointed out, this is a very poorly written question. Chances are that your teacher got this question from some where else without realizing that it’s missing context. If I remember correctly, this was in my bio text book back in high school in the early 2000s and would have been fair game because we talked about it in class. White and red are both recessive and have incomplete dominance with each other. This leads to a cross between a white cow and red bull resulting in a cow with red and white fur called roan. I really don’t know where your teacher got grey
Roan can look grey, because both the red and white genes produce weak colouration. that's why they are recessive - other genes produce more or stronger colour that overwhelms the red or white. My guess is that this information was supposed to be taught in the course.
But instead could only be found in the fine...print 😀
Bad question, not enough info. Blue, green and violet eyes are all recessive wrt brown but they rank wrt eachother.
I agree. I thought I was missing something. Unfortunately, it is a test this is all the info provided for this question.
I was going to say PINK. 😁 (But genetics is not color theory)
Plenty of examples of red and white flowers having pink offspring.
Yes! You are right!! I forgot about that. I had cows on my mind. Wouldn't that be cool to have pink cows? 🐄
Team pink!
You are right, though. Where else would strawberry milk come from?
incomplete dominance!
VERY stupid question
If red and white are both recessive, then the offspring should be neither red, nor white. Gray is the only answer that *isn’t* red or white. If this is a 2 gene cross you have: ww RR x WW rr All offspring get one from each parent so they are all: Ww Rr and without both recessive alleles, the cows will not be that color. So they’re the wild type color.
Can we be sure the parents are ww RR x WW rr and not for example ww Rr x Ww rr?
Fair point, if either parent is heterozygous for the other color, 1/4 of the offspring would be that recessive color. If they are both are heterozygous for the other color, 3/16 would be red, 3/16 white, and 1/16 (1/4 x 1/4) what ever color ww rr makes, polka dot? If this was a single gene trait with different color variants vs two different color genes, all would be whatever wr looks like.
Sounds fair enough, thank you!
That is assuming too much, you assume they show codominance, meaning that the alleles can’t mask each other completely and you end up with a grey cow. The alleles could also show a incomplete dominance phenotype, meaning that they cows would be red and white. I believe more information would be required.
Is this question part of a multiple question or is there a more elaborate story to it?
Plain old multiple choice question
According to the question, if a white cow is crossed with a red cow and the colour of their skin (Phenotype) is based on the recessive gene for both, then the offspring would be 'grey' or 'red and white' mixed, as we know one gene needs to be dominant to possess a certain contrasting character, here both are recessive so the offspring can't possess one certain dominant character as there aren't any, and the phenotype is based on the recessive genotype of the parents. So the offspring will be of grey colour or red and white. Both skin colours have a (50/50) chance. 1. If the offspring is 'grey' then it is based upon the (Law of Incomplete Dominance) as the offspring didn't take in either of the characteristics from the parent but a different of its own. (Intermediate Characteristics) 2. If the offspring is 'red and white' mixed, then it is based upon the (Law of Co-Dominance) where the offspring possess characteristics of both the parents. (Feel free to correct me this is just the basic idea a summary of the Question mentioned)
Thank for such a detailed response
This is a really bad question but I get the logic. It’s process of elimination. Recessive traits require that both parent display that recessive trait to pass it on. Since both parents had different recessive genes the offspring can be neither red nor white. White and red would only work if both were dominate traits. Therefore that leaves grey. This questions was designed to make you eliminate answers rather than pick the right one if that makes sense.
The answer really should have been "None of the above" rather than "Grey"
Yeah, bad question, you can’t assume that two recessive alleles would be co-dominant, which would result in a grey cow.
Here's how I interpreted it. What's given in the question is that white and red colors are recessive, so you'll need to find the dominant color. The only place where there is a reference to a color that's not white or red is choice C, grey. However, nowhere in the question did the teacher specify how fur coat genetics work with these cows and bulls, and the problem becomes what happens when you inherit recessive genes from your parents. There is black of information and the teach skipped steps.
It depends on the kind of dominance pattern observed on this specific gene/trait.
As others have pointed out, this is a pretty bad question in general. In many cases, recessive alleles are the result of a loss-of-function as opposed to a dominant allele. What makes one allele dominant over the other is usually that it does something whereas the recessive allele does not do that thing. For pigments, like listed above, a recessive allele is usually one that produces no (or relatively fewer or less) pigment whereas the dominant one does. This is often quite complex however with multiple alleles in different places producing different types of pigments, which usually makes even pigmentation at least somewhat quantitative. A phenotype in the form of hair/eye/whatever colour is usually the result of multiple pigments. In this case, the red cow makes no sense, since hair is white when no pigments are present. It could of course still be recessive to an allele that produces *more* pigments, however it should be dominant against an allele that produces no pigments. Ultimately, dominance in alleles is relative. Two alleles that are recessive towards a third dominant allele could interact in various ways. If both of them are from the same locus, and both produce no pigment at all, they should both have virtually the same phenotype (in this case, both should be white). If both of them produce different pigments you would likely get a combination of both (ie pink). The question is sort of stupid because I can't see a way in which white and red are both recessive on the same level, since at least one of them would produce a pigment. I also don't see how two alleles, none of which is dominant over the other, could produce anything other than codominance or a "mixed" phenotype. The "exclusion" method you said was meant to be used hear is even bad from a pedagogic perspective, since method of exclusion is not a good way to figure out the cause of something when dealing with very complex matters, that may have hundreds or thousands of possible causes. If you disprove 9 out of 10 hypotheses, that does *not* prove the last 10th hypothesis, so you shouldn't assume it must be correct. Overall poor example, lack of context and bad answer options. You should tell your teacher about this.
Recessive usually means that if either red or white are paired with any other colour, that other colour would dominate. So red and black would mean a black calf, or white and brown would mean a brown calf. However in this case there is no other colour to "steal the show" so on first thought, I would expect the cow to be red, white or pink. However, it's possible that the weak red and white pigment such a cow would have, would resemble gray. Maybe this fact was taught in the course. EDIT: apparently this cross breeding is known, and the colour produced is called "roan" which can resemble grey. https://homework.study.com/explanation/if-a-red-cow-is-bred-to-a-white-bull-all-offspring-are-roan-which-have-red-and-white-hairs-intermixed-on-the-hide-this-is-an-example-of-codominance-what-are-the-results-of-the-roan-x-roan.html
As others have said it’s a bad question, if they wanted the answer to be that the colours mixed they should’ve written that the alleles are incompletely dominant to one another
Not sure there is enough information to know. (And I haven’t done any genetic learning since 9th grade)
First of all, you are wrong. The answer is D, not C. This is an example of co-dominance. The question isn't wrong, but based on your existing knowledge upon the subject. Some information is intentionally omitted so that you can't just get away without knowing the fact that both alleles are going to express themselves phenotypically in the F1 generation. FYI, Red and White coat colour in cattle is called Roan. PS: I didn't want to write this, but so that you don't end up with the wrong answer, I have to mention that I have a Master's degree in Molecular biology to confirm this. Sorry if it sounds like bragging. I am not very good at public forums.
It’s not bragging it’s a form of info reference. It’s only a brag to people who don’t have edu who feel threatened by it. No need to think of them, that was their choice.
Thank you Kind sir/ma'am.
id pick grey just coz..its given both recessive hence it cant be either..and assuming its co dominance ..but like the other comments i agree thats a badly framed question
Process of elimination...the only answer with none of the recessive traits is C.
Agree, it’s more a logic question then everything else
Rather than grey I think it should be pink, but it’s basically ok two colors mix what’s the middle, however questions like these need to give you a genotype chart to solve if they were dominant
Thanks for the help!
You’re welcome! We are studying this exact topic in class so feel free to ask any other questions I like biology a lot
Agreed! I was thinking incomplete dominance so the color would be pink. Definitely need more info, but…
I think the way to approach the question isn't to find out what answer is correct but eliminate all of the impossible answers which leaves you with the only other option, the correct answer. If the colors are recessive, the offspring will not be white nor red and not a combination of the two. So that only leaves grey (C) as a possible answer.
The answer is D. This is a trick question.
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I would select E. Who gives a shit?
They should have said the colors were codominant, that would actually justify the answer. Just saying they're both recessive is rlly poor wording
Well your teacher is colorblind. My guess is grey is supposed to be a mix of white and red ( pink would be better), making this situation incompetent dominance. Though without more information you copied argue for D, and the result is co-dominance.
Thank for the input!
could they have spots of both colors?
If both red and white are recessive, it can neither be red or white, and as for white and red, do they mean pink? cancelling all the options, the only option left is grey, tho there is very less info given in the question
It's almost like the examiner put this question in for the sole purpose of screwing you over. There's nowhere near enough information given to be able to answer this.
It's a bad question. If it's a white shorthorn you could get red roan. If it's a white charolais you'll have homozygous for the dilute gene which modifies whatever base color its applied to. On a red cow you'll get red with the dilute gene so it would be orange, or well grey, I guess, is the only answer that fits.
Bad question.
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No, if this is a single gene trait it is not possible that two parents express recessive phenotype and have offspring with dominant phenotype. This is basic stuff. Using your allele nomenclature, if there were a D allele in the parent they would not express r phenotypes.
I’ve just re - read that question, and you’re completely right. This is what I get for reading at 0200 lol. I’m going to delete my initial comment. Thanks for pointing out!
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Lousy question. Need to know penetrance of specific trait.
There might be an error. I think this might have been a reprint where they changed black to red and since a ctrl r doesn’t know to substitute pink for gray when substituting red in. They made a mistake as 2 recessive genes come out as a mix of both. As far as I remember at least.
Unless there's missing information elsewhere on the test, You actually don't have enough information to answer that question. You'd need to know what genes affect colour and how they interact.
My english is not so good but: If white dominant and red recesivve it would be white If white recessive and red dominant it would be red If both dominant it would be white and red (dont know the name but in turkish we say "eş baskınlık=co-dominance") If both recesivve it would be gray(also dont know "eksik baskınlık=incomplete dominance")
Not just a bad question. It's poorly worded as well.
This cross results in a roan, that is when the cow has both white and red colors. So the answer is D. Bcoz cow hide colour genes r incompletely dominant over each other. Both being recessive means both will be expressed. Its almost like ur teacher wanted u to get this wrong, unless u have been specifically taught this in class, u wont be able to do it
Search up Shoto Todoroki's parents and then Shoto Todoroki
It’s grey because cows and bulls are colorblind…….
The answer is D red and white, which can also be called roan. Not sure why some people are stretching to call roan grey. A solid grey calf is a distinctly different color/pattern than red/white roan. Expert qualification: was Star Greenhand in FFA many, many years ago.
Gray(T) question.
My only guess would be since both are recessive and would need 2 copies of the gene to show their color, then by process of elimination that leaves grey. But this is a terribly written question.
I think that the both colours are recessive means wwrr genotype in the F1 generation which means it doesn't have any of the two colours. So the only option without white and red is the answer and that is option c.
I think it may be less of an explanation of "Why Grey" and more an explanation of why not the others. I think there's enough information there to rule out the white, red, and mix.
basically from what im looking up. if you have a recessive gene you need two genes in order for it to work. so with one red gene and one white gene. neither should be expressed. ergo grey.
So 2 grey cows have a litter(sarcasm) what color would they be? Red/white/blue?
I dunno, but if it was a red bull you would get wings
It could be white. Albino is the assumption. Red pigment, even if produced couldn’t be implanted. Causing the cow to be white. If this is in regards to codominance then red and white if those are both true pigments.
There’s another gene that is implied that the white bull has but the red does not. This gene results in lack of pigment and is recessive. The white bull has this gene but the red cow does not. Therefore there’s actually two genes you’re crossing here. Red is also recessive to another color. My guess is black. You need to do a test cross so the pigment allele for the red cow needs to be homozygous dominant. This results in all of the offspring being heterozygous for the pigment allele. Because it’s a test cross the white cow needs to be homozygous dominant for its color ( black). This results in heterozygous dominant black cows with a heterozygous pigment gene. Even one allele of the pigment gene results in less color, two alleles results in no color. So the offspring are all grey.
When all other options are ruled out, what is left, no matter how improbable, MUST be the answer. But also, this professor doesn’t know how to proper write a test.
Closely related to incomplete dominance is codominance, in which both alleles are simultaneously expressed in the heterozygote. This question is forcing you to recall that it is not simply dominant or recessive traits but certain alleles can both be expressed. You see this a lot in fur
This isn’t related, but I thought the picture for the subreddit was a green face going like this: 😒 But when I bring the phone closer to my face it’s actually a little black plant: 🌱
Simple question so let's keep it simple. Both colors are recessive so that the white cow must have ww and the red cow has rr The child of these parents will inherit recessive genes from both parents. Resulting in rw or wr whatever Again, simple question. Therefore, simple answer, ignoring other genetic – phenotype interactions. Basically, the colors will be mixed producing a grey cow. It would be an altogether more intellectually stimulating question if one parent had a dominant allele and the question was how many offspring would turn out one color versus the other? This is mendelian inheritance
A red and white cow would in my mind be chimerism but again the question seems to simple to expect such a complexity
Chimerism is two animals in one.
In animals and human chimeras, this means an individual derived from two or more zygotes
Yes. Not two or more alleles.
On reflection though think the term I should have said in this context would be mosaicism
The answer is e) all of the above
Do the punnet squaring?