Bio Question: Being considered carrier for a non-lethal gene

[HannibalLecter]

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This inquiry stems from this question:

Steve and Anna are both carriers for a non-lethal, autosomal, recessive condition. What is the probability that their first child will be a carrier for the condition?
A.0%.
B. 25%.
C. [Correct] 50%.
D. [Yours] 75%.
E. 100%

If the child ends up being homozygous recessive for the gene isn't he or she still considered a carrier for the gene since they still contribute it to the gene pool.

Should the carrier genotype be the only way you can be considered carrying the gene or could you be homozygous recessive and still considered to be carrying the gene?

 

[carolinagrl346]

This inquiry stems from this question:

Steve and Anna are both carriers for a non-lethal, autosomal, recessive condition. What is the probability that their first child will be a carrier for the condition?
A.0%.
B. 25%.
C. [Correct] 50%.
D. [Yours] 75%.
E. 100%

If the child ends up being homozygous recessive for the gene isn't he or she still considered a carrier for the gene since they still contribute it to the gene pool.

Should the carrier genotype be the only way you can be considered carrying the gene or could you be homozygous recessive and still considered to be carrying the gene?

"Carrier" always means heterozygous, the individual does not express the trait but "carries" it. I don't think I've seen it explained another way.

 

[jmukid]

If the parents are both carriers it means that they are both heterozygous. So for example both could be Bb x Bb. Crossing over produces 1 BB, 2 Bb and 1 bb. BB means that they are not the disease carrier. Bb since heterozygous means it is carrier and bb means it actually has the disease. Since 2 of the 4 possibilities are Bb then the first child has 50% chance of being a carrier.

 

[HannibalLecter]

Hmm I don't think you guys get what I am trying to ask. I know a heterozygous is Bb and its 50% of that genotype arrising in F1 but I am trying to ask what the definition of a carrier could encompass because technically bb as a homozygous is still a carrier for that gene since it is non-lethal.

 

[Demps]

Hmm I don't think you guys get what I am trying to ask. I know a heterozygous is Bb and its 50% of that genotype arrising in F1 but I am trying to ask what the definition of a carrier could encompass because technically bb as a homozygous is still a carrier for that gene since it is non-lethal.

carolinagrl346 is correct where she mentions that carrier is always heterozygous. You would call homozygous recessives "affected" or have the disease per se. But you do not call them carriers because they "express" the mutant phenotype.

And I am not 100% positive, but based on the genetics questions I encountered during undergraduate, the term "lethal" applies to the HOMOZYGOUS DOMINANT being dead at birth. This means the dominant phenotype people are always heterozygous. hence if the questions did tell you that the gene was lethal, then BB dies at birth and 66.67% of the individuals will be Bb "carriers" and 33.33% will be bb "affected."

The question told you non-lethal just to clarify you that homozygous dominants do not die at birth.

 

[Ehtar Moriarty]

Hmm I don't think you guys get what I am trying to ask. I know a heterozygous is Bb and its 50% of that genotype arrising in F1 but I am trying to ask what the definition of a carrier could encompass because technically bb as a homozygous is still a carrier for that gene since it is non-lethal.

There are two types of people for this disease: Affected and Unaffected. Since this is a recessive disease only a Homozygous Recessive will be affected and display the diseased phenotype.
There are however two different ways to be unaffected:
You could be normal and not have either diseased allele (Homozygous Dominant)
Or You could be a Carrier and have one Normal allele and "carry" one diseases allele and display a normal "Phenotype"
Yes you are correct a Homozygous recessive is technically "carrying" to diseased alleles, but that language is not used typically in genetics...,
In genetics, the term Carrier is defined as someone who displays a normal phenotype but contains at least one diseased allele in their genotype.
Furthermore, any individual that has a Homozygous genotype for any diseased allele, dominant or recessive, is simply referred to as "Diseased" or "Affected".
I hope this clears everything up, good luck

 

[JustwantDDS]

hmm i get what ur saying hannibal
but ur over thinking it
just think of carrier as hetero, like the parents 🙂