I have a question about genetics... please help!?

Different types of snapdragons produce different colored flowers. If you cross a true breeding red flowered variety with a true breeding white flowered variety- the offspring will all produce pink flowers. If you cross the pink flowered plants with each other, you get 1 red, 2 pink, and 1 white flowered plant. Red flowers are so because of a pigment called anthocyanin, and the pigment is the product of a biochemical pathway consisting of several chemical reactions, each catalyzed by a specific enzyme.





Based on what you know about how genes work, please explain why the white flowers are white rather than red.

I have a question about genetics... please help!?
stop posting your homework questions
Reply:It seems to me that based on that information the white flowers are white because the gene to produce a white flower blocks the biochemical pathway that creates the anthocyanin. So, in the pink flowers the gene is only partially blocking the pathway.
Reply:I know zip about genetics.


But I do know a bit about optics, and the fact is, there are a lot of colors that humans can't see, like infared.





So maybe there are color variations going on there, but we can't see them, because they're up out of the range that we are able to see.





You know, the same way that sounds above 20,000 hz can't be heard by us, but dogs go crazy hearing them.


That doesn't mean the sound isn't happening.


So maybe these colors are actually happening.





Just a while guess.
Reply:ok you know that the genotype of the first generation are all heterozygouse, red and white, which is why you get all pink flowers (red +white= pink) in this case you know that the alleles red and white are not dominant or recessive with respect to one another. each flower from the first generation has red allele R and a white allele W, so if you cross the two together you get (do the punnet square)


...R.....W





R RR RW





W RW WW











you have one offspring RR which is red, two are RW which means they are pink, and one is WW which means its only white.... hope this made any sence....
Reply:ah... looks like someone's still in school
Reply:To visualize how combining two pink flowers could produce a red, 2 pink and 1 white, draw a square. Draw a cross in the middle of the square so there are 4 sections. We will label colors as follows RR = red, Rr = pink, rr = white. Now go to your box. Both flowere are pink so they are Rr. On the top left of your box write R and on the top right write r. That represents one pink (Rr) flower. Now go to the left side of your box. On the top left write R and on the bottom left write r. This represents the other pink flower. Now lets put them together. At the top left of the box you will find an R. Put this in the top left square. Now go to the side of the box. The top left has an R. Put that in the top left square. It should have RR in it which means a red flower. Now go to the top right of the box which has an r and put it into the top right section. Go to the left side of the box at the top where you will find an R. Put this in the top right section. You will have an Rr in that box which means a pink flower. If you combine the R on the top left and the r on the bottom side you will get another Rr - pink flower. Finally, if you put the r from the top right in the bottom right section and the r from the bottom of the left side into the bottom right section, you will have rr - a white flower.What you just made was a punnett square used in genetics to determine the probability of certain traits in offsprings. Dominant features are represented by a capital letter and recessive features by a small letter. Try your square with eye color. Brown is dominant and blue is recessive. Brown will be represented by B and blue by b. Wherever there is a B, the eye color will be brown so you could only have blue eyes with bb. Pretend your parents both have brown eyes but are carrying the recessive gene "b" for blue eyes. They each would be represented by Bb. Set up your punnett square with B and b on the top and B and b on the side. Cross them like you did with flowers and you will see that the chances are that 1 offspring will be BB - that is homonenous (the same dominant genes) for brown eyes. 2 of the offsprings will have brown eyes but they have Bb - genes for both brown and blue eyes (called heterogenous ) but end up with brown eyes because brown is dominant. In one square you will have bb and that offspring will have blue eyes. It's kind of fun and you can use this with all kinds of traits to predict the possibilities of outcomes for different traits in offsprings. Kind of long but I hope it helped you understand.
Reply:In snapdragons the allele for Red colour (R) is incompletely dominant to White (W)


Parental RR X WW





gametes R W





F1 All RW (an intermediate which are pink)





RW X RW





gametes R, W R, W





F2 1 RR : 2RW : 1WW








Hope this helps!