Expression of the A and B antigens on red blood cells is influenced by the FUT1 gene. This gene encodes fucosyl transferase, an enzyme that helps produce the H substance. Which of the following statements about the H substance is incorrect?

Individuals that cannot produce the H substance appear to be type O even if they have functional A and/or iB alleles.
Individuals that fail to produce the H substance are said to have the Bombay phenotype.
Individuals that are heterozygous for the FUT1 gene cannot produce the H substance
The H substance is a substrate for the enzymes produced by the n and β genes. These enzymes add the appropriate terminal sugar to the H substance producing the A and B antigens, respectively. ︵

The following statements about the H substance that is incorrect is

(Individuals that are heterozygous for the FUT1 gene cannot produce the H substance)

Explanation: substance H is found on virtually all the red blood cells. FUT1 gene encodes fucosyl transferase, an enzyme that helps produce the H substance. They are used as precursor for the formation of A and B antigens. From the statements;

-Individuals that cannot produce the H substance appear to be type O even if they have functional A and/or iB alleles, Is a correct statement.

-Individuals that fail to produce the H substance are said to have the Bombay phenotype. This is a correct statement.

-The H substance is a substrate for the enzymes produced by the n and β genes.

- These enzymes add the appropriate terminal sugar to the H substance producing the A and B antigens, respectively.

But if a person carries even a single functional copy of FUT1 gene, that is, heterozygous or homozygous then he or she can efficiently produce H antigen. Therefore (Individuals that are heterozygous for the FUT1 gene cannot produce the H substance) is an incorrect statement.

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enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products