Pure or Hybrid
Are you a hybrid? Or are you pure? We all have a collection of traits that our parents have passed down to us. Something called genes control these traits. Genes are made of DNA and traits are made of genes. You have two genes for each trait that you have. For each trait, you receive one gene from your mother and one gene from your father. This means you can either be pure or hybrid. All that being a hybrid means is that you have two different genes for that trait. If you are pure, then you have two of the same gene for that trait. Being a hybrid or pure can be represented by your genotype. A genotype is a symbol to represent if you are hybrid or pure for a specific trait. This symbol is made out of two letters. An uppercase letter represents a dominant gene. A lowercase letter represents a recessive gene. So if you were a hybrid and you had brown eyes and brown hair, the genotype would be Bb. You would have one gene for dark hair and eyes, but also one gene for light hair and eyes. If you had blue eyes and blonde hair your genotype would be bb and you would have two genes for light hair and eyes. You would be pure because blue eyes and blonde hair are recessive and cannot show up if there is a dominant gene present, such as brown hair and brown eyes. Refer to the Dominant and Recessive page for more information on dominant genes and recessive genes. You could still be pure for dark hair and eyes, though. Your genotype would be BB since dark is dominant and you would have two genes for dark.
There is a way to predict the genotype for the offspring of two parents. This is called a punnet square. It basically just a prediction box. What you first need to do is draw a square and draw two lines it to make it into four boxes.
There is a way to predict the genotype for the offspring of two parents. This is called a punnet square. It basically just a prediction box. What you first need to do is draw a square and draw two lines it to make it into four boxes.
Then beside the outside of the square, put the mother's genotype down the left side of the square and the father's genotype across the top of the square like so.
All that you have to do now is fill in the four predictions. Bring one letter down and the other one across to find the genotype like in the picture.
Now do the same thing to the other boxes in the square. Bring one letter over, bring the other one down.
And there you have it. It each box is represents a 25% chance of what the genotype will be. This works with all genotypes for the mother and father. They can be pure or hybrid because it will work both ways. Just follows these steps and pictures to create a punnet square. You can find out if the offspring has a higher chance of being pure or hybrid.