Define and distinguish incomplete penetrance and variabl...

Question

Define and distinguish incomplete penetrance and variable expressivity.

Accepted Answer

Hello, everyone. Welcome back. Here's our next question. It says which of the following is a measure of the percentage of individuals with a given all who exhibit the phenotype. And our choices are a expressivity B penetrance, C codominance or D epitasis. So we're asking about individuals who have inherited a gene but not all express the phenotype. So you'd say what percent do and that measure is choice B penetrance. So again, penetrate is when you have that situation of the gene is inherited but not always has an, doesn't always have an effect on the phenotype. This is a little easy to mix up with choice. A expressivity expressivity is when a given gene has a variable effect on the phenotype. So while penetrate says you've inherited the gene, but you don't uh express any, any degree of it in the phenotype expressivity says you've inherited the gene. It has an effect on your phenotype, but that effect can vary from individual to individual. Not every person with the gene expresses it in the same way. So they're easy to mix up, but that's a distinction between them. So that's why choice A isn't the correct answer then choice C codominance is when you have two dominant, all that both get expressed when they're inherited together. So that's why that's not the correct answer. And then choice D epitasis involves the interaction of two different genes where the expression of one affects the expression of the second in the phenotype. So the similarity to penetrance or expressivity is that you can see uh say, you know, a particular gene for color is expressed in a variety of ways. But in this case, it's due to the effect of a second gene, not a variable expression of one particular gene. So that's why trust the epitasis isn't our answer. So again, which of the following is a measure of the percentage of individuals with a given allele who exhibit the phenotype. And that's choice B penetrance. See you in the next video.

Define and distinguish incomplete penetrance and variable expressivity.

Key Concepts

Incomplete Penetrance

Variable Expressivity

Genotype-Phenotype Relationship

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