Try breeding some dragons to see if you can figure out any rules that govern which dragons have horns. |
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Now try breeding some dragons to see if you can figure out any rules that govern which dragons have wings. Click the button to breed possible children from these pairs. |
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Do you have an idea about how wings are inherited? Try the two scenarios below to see if they confirm your suspicions. |
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When both dragons have undergone meiosis, you can combine two gametes and fertilize them to create a child. Click one of the four gametes under each dragon and use the arrow buttons to move them into the middle. Before you click play to run fertilization, zoom in with the magnifying glass. Can you predict how the child will look just by examining the genes? (Note: You can click and drag the chromosomes to separate them for a better look.)
Now zoom in on our Daddy dragon. Your goal will be to create a child dragon with wings, but no legs. To inherit these traits, the child will need to have the gene combinations ww and ll .
Can the father provide his half of these combinations?
Now reset the meiosis and zoom in on our expectant mother dragon. Run meiosis a few times. (Note that you will have to return to the un-zoomed view and hit "reset" to get a fresh run).
If we want to "design" a child dragon with the gene combinations
ww
and
ll
, can the mother carry through on her part of the bargain?
If you looked closely, you noticed that we have a problem. The mother can only give chromosomes with the genes Wl or wL. And neither of these will help us in our quest. Fortunately, there's a catch… Zoom in on the mother and press the triangular "play" button again. The process will stop halfway through and wait for you. When it does, click on one chromosome with the tip of your mouse. See the flashing arrows? The arrows show places on other organisms you can click. Try it.
Congratulations, you just created a child by crossing genes over! (This is also called genetic recombination, by the way.) Zoom out to reset things, and try a few more times. Can you create our desired ww and ll dragon now? Give it a shot.
When you think you've succeeded (and before you proceed to breed the child!), zoom in on the chromosomes you crossed over and take a snapshot for your lab notebook. Write a note to go along with the snapshot describing what you did and why you think it will make the correct child dragon.
Use the cross tool to breed a new generation of dragons. Then breed two of the dragons from this new (F2) generation together. Repeat this as far as you wish. What do you notice about the dragons as you continue to breed more generations this way?
Use the chromosome tool to examine the genes of the dragons more closely. Can you find any genes that are different among the members of your F8 generation? How many generations do you have to breed until all the dragons are exactly the same?
You are creating an inbred strain of dragons in the last generations of this process. When you think you have succeeded in creating a strain, use the button above to take a snapshot of your strain for your lab notebook. Along with the snapshot, write a note describing your strain, and explain what is special about all individuals in an inbred strain of organisms.
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