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Today we're going to learn about genetics using dragons.




Click here to begin or here.

OK, now that you understand the model, here are two questions. Try to answer them without using the model, but if you have to use the model to remember something, that's all right.

If you see a dragon with wings, is it possible to tell which alleles it carries for wings (in other words, whether it is WW, Ww, wW, or ww)? Explain.

If you see a dragon with horns, is it possible to tell which alleles it carries for horns (in other words, whether it is HH, Hh, hH, or hh)? Explain.


Change a gene and see what happens to the dragon.

Remember to use the scroll bar to see all the chromosomes! (Dragons have three pairs of chromosomes.)

Note the difference, at the chromosome level, between male and female dragons. See if you can figure out the rule that links a dragon's genes (its "genotype") to its appearance (its "phenotype").

When you think you understand how this model of genetics works, click on the button below and we'll ask you a few questions about it.


Welcome back to the chromosome laboratory! You can come here whenever you like to play with the model and remind yourself how a dragon's genes (its genotype ) determine its physical traits (its phenotype. )

Remember to use the scroll bar to see all the chromosomes!


This is the Meiosis and Fertilization view.

  • The round circles under the dragons are "germ cells".
  • Click on the "Play" button to run a simulation of meiosis.
  • Select one of each of the four gametes and click on the arrow key to move it into the fertilization chamber in the middle.
  • Run the fertilization animation by clicking on the "Play" button in the middle and -- presto! -- a new dragon will appear.
  • Try this a few times with different gametes and observe the differences in the traits of the baby.

Background knowledge: The new dragon gets its genes, and therefore its phenotype, from the gametes, so if you look at the chromosomes in the gametes -- and you know the genotype-to-phenotype rules! -- you should be able to predict what the baby dragon will look like. If you want to see the genes in the gametes, click on the little magnifying glass in the lower left corner of the gamete window.


You are looking at the chromosomes of the mother under a magnifying glass. The labels attached to the chromosomes are the alleles -- the different versions of the genes. If you run Meiosis all the way to the end (either by using the Play button or by dragging the slider all the way to the right) the alleles will line up at the top of the window so you can see them more clearly.


You are looking at the chromosomes of the father under a magnifying glass. The labels attached to the chromosomes are the alleles -- the different versions of the genes. If you run Meiosis all the way to the end (either by using the Play button or by dragging the slider all the way to the right) the alleles will line up at the top of the window so you can see them more clearly.


You now have two gametes in the fertilization chamber -- one from each parent. Hit the Play button or drag the thumbnail to the right to run fertilization and create an offspring.


You have selected a gamete from the father. If you want to use this gamete for fertilization use the arrow key to move it into the fertilization chamber.


You have selected a gamete from the mother. If you want to use this gamete for fertilization use the arrow key to move it into the fertilization chamber.


Congratulations, you've made a new baby dragon! Its physical traits are determined by its genes, using the rules you've already investigated. Half of those genes came from its mother and the other half from its father, which is why it has traits from both parents.


You did it! Congratulations!!!

Click on the "Next Challenge" button.


Oops! That baby doesn't have wings. It must have the wrong genes.

Remember, the only way you can control which genes the baby will have is by picking the right gametes for fertilization. Hit "Reset" and try again. (Reset will run a different meiosis in which the chromsomes will end up in randomly different gametes.)


Silver Challenge: Make a baby with wings


Here are two new dragons to play with. Note that neither has wings!

  • Run meiosis and pick just the right gametes to get a baby with wings.
  • Use the magnifying glass with the "plus" sign in it to zoom in and see the genes in the gametes.
  • Use the magnifying glass with the "minus" sign to return to the meiosis view.
  • Challenge: Try to get the winged baby with only one try!

(Hint: If you've forgotten which gene combination makes wings, go back to the chromosome view and figure it out.)


Gold Challenge: Make a baby with four legs.


OK, here's another challenge. Try to give these two dragons a baby that has four legs. Use the "Chromosome View" button if you need to refresh yourself on the rule for legs.


No, that baby has no legs. You were supposed to make one with four legs. That one must have the wrong genes. Hit "Reset" and try again.

If you don't remember the rule for legs, go to the chromosome view and figure it out.


No, that baby has two legs. You were supposed to make one with four legs. That one must have the wrong genes. Hit "Reset" and try again.

If you don't remember the rule for legs, go to the chromosome view and figure it out.


Well done! If you want to keep going click on the "Extra credit" button.


Platinum Challenge: Make a green dragon with a plain tail.

Here's an extra credit challenge: try to make a green dragon with a plain tail. Note that this time we are asking for two traits -- color and tail shape -- that are controlled by two different genes. This is a harder challenge than the first two.


That dragon is the wrong color and it has a fancy tail. You're trying to make a green dragon with a plain tail. Run Meiosis and try again. (Note: each time you run Meiosis the chromosomes move randomly. Sometimes if you don't get the gene combinations you want it pays to run Meiosis again -- the results might be different!)


That dragon has a fancy tail. You're trying to make a dragon with a plain tail. Run Meiosis and try again. (Note: each time you run Meiosis the chromosomes move randomly. Sometimes if you don't get the gene combinations you want it pays to run Meiosis again -- the results might be different!)


That dragon is the wrong color. You're trying to make a green dragon. Run Meiosis and try again. (Note: each time you run Meiosis the chromosomes move randomly. Sometimes if you don't get the gene combinations you want it pays to run Meiosis again -- the results might be different!)


You did it -- you made a green dragon with a plain tail! Congratulations! That's the last challenge.

 female 1 a:b,b:B male 0 a:B female 1 a:h,b:h,a:w,b:W,a:L,b:l,a:t,b:T,a:F,b:f,a:a,b:A,a:B,b:B male 0 a:H,b:h,a:W,b:w,a:L,b:l,a:T,b:t,a:f,a:a,a:B false