By Nanna M. Andersen | Published: 07.02.22 | Edited: 02.07.23 If you want to learn how to calculate outcome using Punnett Squares I'll give you my metode and hope it will help you get started. Lets start with a starting with a simple calculation; let's determine the pairing between an Agouti buck that carries Black (Aa) and a Black doe (aa). We'll use a Punnett square to calculate the possible genotypes of their offspring. The buck's genotype is "Aa," where "A" represents the dominant Agouti gene and "a" represents the recessive Black gene. The doe's genotype is "aa," indicating that she has two recessive Black genes. We begin by writing the buck's individual genes (blue) on the top of the Punnett square: "A" over the first column and "a" over the second column. Then we carry down the letters into the squares below. Next, we write the doe's individual genes (red) on the side of the Punnett square and carry them into the squares. Each square now represents a possible genotype for the offspring, with each square having a 25% probability. The Punnett square shows the following outcomes:
When learning this skill repetition is key. I recommend write down as many calculations as possible to make sure this simple calculation makes sense to you. Now, let's move on to a more complex calculation involving two different genes. The buck is Agouti (Aa) and carries the Mink gene (Mm), while the doe is Mink (aa mm). Again, we have to put these genes into a Punnett Square. This times however we need to determine the unique genes each parent can pass on to their offspring. The buck can pass on four different combinations from his genotype:
The doe can only pass on one combination:
The Punnett square now consists of four squares, each representing a 25% probability. This means that each pup will have a 25% chance of having one of the following genotypes:
If you feel confused by this calculation I want you to read the parent's genotype again. This time count the individual forms of each gene from each parent. The doe only have two individual forms to pass on; "a" and "m". While the buck have four individual forms to pass on; "A", "a", "M" and "m". To make the calculation even more complex, let's introduce another locus: the C locus, also known as the Color locus. Unlike most loci, the C locus has five different genes: C, c^t, c^m, c^h, and c. The C gene is completely dominant over the other four genes, but when the recessive genes are combined, the other four genes exhibit incomplete dominance towards each other, resulting in various color varieties. This makes the locus notorius hard to master but in fact the genes are as simple as any other gene when calculating Punnett squares. We'll use an Agouti Tonkinese buck that carries Mink (Aa ctct Mm) and a Black doe that carries Himalayan and Mink (aa Cch Mm). Following the same steps as before, we determine the individual genes each parent can pass on. The buck can pass on the combinations:
The doe can pass on the combinations:
Because we have more combination we need a bigger Punnett square. This will of 16 squares, each representing a 6.25% probability. Each pup will have the following percentage chance of having one of the following genotypes:
Lastly, remember to always determine each parent's unique genes that can be passed on to the offspring, and make sure the genotypes of both parents mirror each other for the Punnett square to work accurately; meaning that if you add the doe's D genes, you must also add the buck's D locus genes. Writing down and practicing these calculations in a notebook can help improve your skills over time. Here are the key points to remember when learning to do Punnett square calculations:
Remember, starting with simple calculations and gradually increasing the complexity will improve your skills over time. Good luck with your Punnett square calculations!
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