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Chapter 4: Problem 6

Karl Landsteiner and Philip Levine discovered a glycoprotein expressed on the surface of red blood cells, which exists in two forms, \(M\) and \(N .\) An individual may produce either one or both of them. The alleles \(L^{M}\) and \(L^{N}\) control the expression of the glycoprotein. What type of inheritance does the MN blood group exhibit, and what are the genotypes of the phenotypes observed in the human population?

Short Answer

Expert verified
Answer: The MN blood group exhibits co-dominant inheritance. The possible genotypes are \(L^{M}L^{M}\) (expression of M glycoprotein only), \(L^{N}L^{N}\) (expression of N glycoprotein only), and \(L^{M}L^{N}\) (expression of both M and N glycoproteins).

Step by step solution

01

Identify the type of inheritance

From the information given, we know that individuals can produce one or both glycoproteins on the surface of their red blood cells, indicating that the glycoprotein is inherited via a co-dominant trait. This means that both alleles \(L^{M}\) and \(L^{N}\) are expressed when they are present together, resulting in individuals displaying the M, N, or both phenotypes.
02

Determine the possible genotypes

Now that we know the MN blood group exhibits co-dominant inheritance, we need to list the possible genotypes that result from the combinations of the alleles \(L^{M}\) and \(L^{N}\). Using the 2 alleles, we can create the following genotypes: 1. Homozygous dominant for M: \(L^{M}L^{M}\) 2. Homozygous dominant for N: \(L^{N}L^{N}\) 3. Heterozygous for both M and N: \(L^{M}L^{N}\)
03

Determine the phenotypes corresponding to the genotypes

Each genotype results in a specific phenotype. In this case, we have: 1. Homozygous dominant for M (\(L^{M}L^{M}\)): Expression of M glycoprotein only 2. Homozygous dominant for N (\(L^{N}L^{N}\)): Expression of N glycoprotein only 3. Heterozygous for both M and N (\(L^{M}L^{N}\)): Expression of both M and N glycoproteins (due to co-dominance) In summary, the MN blood group exhibits co-dominant inheritance with the possible genotypes being \(L^{M}L^{M}\), \(L^{N}L^{N}\), and \(L^{M}L^{N}\). These genotypes result in the following phenotypes: expression of M glycoprotein only, expression of N glycoprotein only, and expression of both M and N glycoproteins.

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