Calculating Genetic Probabilities with Punnet Squares

In summary, the odds of wearing shirt #1 or pants #1 is 3/4 or 75%, not 100%. This is because there are 3 out of 4 possible outcomes that meet the condition, and the remaining 1 out of 4 outcome of wearing both shirt #1 and pants #1 is excluded. It is important to carefully consider the conditions when determining probabilities.
  • #1
at2341
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I'm trying to work out genetic probabilities using the punnet square.

Let's say I have 2 shirts and 2 pants. The odds of me wearing shirt #1 is 1/2. The odds of me wearing pants #1 is 1/2. Does this mean that the odds of me wearing shirt #1 or Pants #1 is 1 (100%) (addition rule - 1/2 + 1/2). This seems counterintuitive.

Is the answer that I have to subtract out from 100% the odds of me wearing BOTH shirt #1 and pants #1?

Thanks
 
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  • #2
at2341 said:
I'm trying to work out genetic probabilities using the punnet square.

Let's say I have 2 shirts and 2 pants. The odds of me wearing shirt #1 is 1/2. The odds of me wearing pants #1 is 1/2. Does this mean that the odds of me wearing shirt #1 or Pants #1 is 1 (100%) (addition rule - 1/2 + 1/2). This seems counterintuitive.
No, it's not simple addition.

When you are looking at the probability of wearing shirt 1 OR pants 1, how many possible outcomes total do you have of shirts and/or pants? And how many possible outcomes would fulfill the requirement of having shirt 1 OR pants 1? [/quote]
Is the answer that I have to subtract out from 100% the odds of me wearing BOTH shirt #1 and pants #1?
No, that's not what you would subtract out. Though, one should be careful of how the question is phrased. If you need to determine any combination where shirt 1 or pants 1 (or both) is included, then both is within that same set of outcomes you need to consider, and the only outcome that will NOT satisfy your conditions is shirt 2 and pants 2 together.

On the other hand, if it says shirt 1 OR pants 1, but NOT both, then the outcome with shirt 1 AND pants 1, as well as the outcome of shirt 2 AND pant 2, are both excluded.
 
  • #3


I would like to clarify that calculating genetic probabilities using Punnet squares is a method used to predict the likelihood of specific traits being passed down from parents to offspring. It is not the same as calculating the odds of choosing certain clothing items to wear.

In genetics, the Punnet square is a visual tool used to represent the possible combinations of genes that can be inherited from each parent. Each box in the Punnet square represents a different combination of genes, and the probabilities are based on the laws of genetics and the known traits of the parents.

Therefore, the addition rule you mentioned does not apply here. The probabilities of inheriting specific traits are not simply added together, but rather calculated based on the inheritance patterns and the genes present in the parents.

In regards to your example of clothing items, the odds of wearing a certain shirt or pants would depend on personal preference and choice, not on the laws of genetics. So, the addition rule would apply in that scenario.

I hope this clarifies the difference between calculating genetic probabilities and calculating odds in other situations. It is important to use the appropriate methods and rules for each context.
 

Related to Calculating Genetic Probabilities with Punnet Squares

1. What is a Punnet Square?

A Punnet Square is a tool used to predict the likelihood of certain genetic traits being inherited by offspring. It is a grid that allows scientists to visualize the possible combinations of genetic traits that can result from a specific mating.

2. How do you use a Punnet Square to calculate genetic probabilities?

To use a Punnet Square, you first need to determine the genotypes of the parents. Then, you can fill in the squares with the possible combinations of alleles from each parent. Finally, you can use the ratio of dominant and recessive alleles to calculate the probability of certain traits appearing in the offspring.

3. What is the difference between genotype and phenotype?

Genotype refers to the specific genetic makeup of an individual, including both dominant and recessive alleles. Phenotype, on the other hand, refers to the observable characteristics or traits of an individual, which are determined by their genotype.

4. What are the limitations of using Punnet Squares to calculate genetic probabilities?

Punnet Squares can only provide accurate predictions if the inheritance of traits follows simple Mendelian genetics and if the genotypes of the parents are known. They also do not take into account other factors such as environmental influences that can affect the expression of genetic traits.

5. Can Punnet Squares be used for all organisms?

Punnet Squares can be used for most sexually reproducing organisms, as long as their genetics follow simple Mendelian inheritance patterns. However, they may not be as accurate for more complex genetic systems or organisms with a high degree of genetic variation.

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