I learned genetics when I was 5. My mom loved breeding rats to see what kind of babies would come out ant taught me the logic. It's sad and frustrating that others think it's curing cancer, so I'm writing this book to help people understand!
Contain...
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This is a Punnet Square. Cool, right? It's used to calculate genetics of some children.
Now before we can use this, we need to know some vocabulary.
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Trait - A look or change, like fur, eye or hair color. Made of two genes.
Homozygus - The two genes making up a trait are the same.
Heterozygus - The two genes making up a trait are different.
Dominant - overshadows more recessive genes.
Recessive - is hidden by more dominant genes
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Now, let's look at a full Punnett Square, with two parents.
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In this picture, there are two parents. One is heterozygus, which means they carry a gene for yellow and green. One is homozygus, and they carry only green.
Notice how it only takes 1 copy of the yellow gene to make a yellow child. This means that the yellow gene is dominant. We show dominance with an big Y- y for Yellow.
The green gene, the little y, takes two genes to show. The yellow gene will overshadow the green gene if they are both in a trait, which means that a recessive trait requires two of the same copy to show.
Overshadowing does NOT, however, mean that the green gene is erased. The green gene is still there, just not shown. If there is another parent with a green gene that looks yellow, there's a chance their kid can be green, even though both parents seem yellow. You must be careful and test for traits if you want to breed a certain type of organism.
This all together means we can predict what a kid can look like. Take a look at the picture again. Notice that there's a little picture of a bean. This is a prediction of what the baby bean plant will look like. These two parents have a 50% chance for a yellow baby and a 50% chance for a green baby.
This is useful, especially when there's more than 2 kinds of gene that can go into a trait!
Next chapter we'll take a look at when there's more than 1 kind of gene you can have, or when there's intensity instead of total change.
