A mix-up in a hospital ward caused a mother with O and MN blood types to think that a baby given

A mix-up in a hospital ward caused a mother with O and MN...

A mix-up in a hospital ward caused a mother with $\mathrm{O}$ and $\mathrm{MN}$ blood types to think that a baby given to her really belonged to someone else. Tests in the hospital showed that the doubting mother was able to taste PTC (see problem 3 ). The baby given to her had $\mathrm{O}$ and $\mathrm{MN}$ blood types and had no reaction when the bitter PTC chemical was placed on its tongue. The mother had four other children with the following blood types and tasting abilities for $\mathrm{PTC}$ : Type A and MN blood, taster b. Type B and N blood, nontaster c. Type A and M blood, taster d. Type A and N blood, taster Without knowing the father's blood types and tasting ability, can you determine whether the child is really hers? (Assume that all her children have the same father.)

A mix-up in a hospital ward caused a mother with $\mathrm{O}$ and $\mathrm{MN}$ blood types to think that a baby given to her really belonged to someone else. Tests in the hospital showed that the doubting mother was able to taste PTC (see problem 3 ). The baby given to her had $\mathrm{O}$ and $\mathrm{MN}$ blood types and had no reaction when the bitter PTC chemical was placed on its tongue. The mother had four other children with the following blood types and tasting abilities for $\mathrm{PTC}$ :
Type A and MN blood, taster
b. Type B and N blood, nontaster
c. Type A and M blood, taster
d. Type A and N blood, taster Without knowing the father's blood types and tasting ability, can you determine whether the child is really hers? (Assume that all her children have the same father.)

Key Concepts

Blood Type Inheritance

This concept involves understanding how blood groups are passed from parents to offspring, including systems like the ABO and MN blood groups. It provides a framework for matching parental blood types with those of their children and is crucial in evaluating genetic relationships in medical and forensic contexts.

Dominant and Recessive Inheritance

In genetics, traits are often governed by dominant and recessive alleles. A dominant allele will express its trait even if paired with a recessive one, whereas a recessive trait is only expressed in the homozygous state. This principle is key when analyzing traits such as PTC tasting, where the taster trait is dominant and non-tasting requires inheritance of two copies of the recessive allele.

PTC Tasting Genetics

PTC tasting is a well-known example of a Mendelian trait governed by a single gene with a dominant allele for tasting and a recessive allele for non-tasting. Understanding this trait helps in reconstructing possible parental genotypes from observed offspring phenotypes, thereby assisting in verifying biological relationships.

Genetic Markers in Parentage Analysis

Genetic markers such as blood group antigens and specific trait alleles (like those involved in PTC tasting) are used to determine biological relationships between individuals. By comparing these markers among family members, one can assess whether a child’s genetic makeup is consistent with that of a given parent.

Transcript

00:01 Okay, in order to solve this question, we have to talk about padded squares and also frequencies.

00:05 Okay? it says that a mix -up in a hospital work goes a mother with o and m -blood types to think that a baby given to her really belongs to someone else.

00:16 Okay, apparently here we're going to have three genes.

00:19 Okay, first, for a -b -o group, remember that we have, that's writing like this.

00:26 A -a is going to have a -type blood, okay? a and o -e.

00:31 O is going to give also a type, b b is going to give b type, b o is going to give b type too, then it is a co -dominant so ab is going to give a -b type.

00:48 And finally, absence of a or b is going to give o type.

00:53 Okay, and what about m in blood? well, if you have two m, it's going to be m type.

01:00 If you have mn, you're going to have mn type, and nn is going to give n type.

01:10 Finally, about ptc.

01:13 The ability to taste ptc, taster, is nominal.

01:19 Let's express it like p, dominant, or better like, yeah, with p would be.

01:27 And non -taster is lowercase p.

01:32 So practically ep dominant is going to be taster.

01:40 Heterosigozygos are going to be taster too.

01:43 And homocybo dominant is going to be recessive.

01:45 It's going to be non -taster.

01:48 Okay.

01:50 And so it says the model has type o blood.

01:56 It means in this.

01:57 Type o blood and nn also.

02:02 Okay.

02:04 The mother also is able to taste ptc.

02:06 So her gerotype for ptc is going to be p and we don't know the second elite because tastert can be either homosexuals dominant or tetracycule.

02:14 Okay, this is for the mother.

02:18 Now the baby given to her had o, okay, the baby, let's write it here, maybe.

02:27 It has o type, o blood type and mn to mn and had no reaction when the bitter ptc chemical was played on its tongue.

02:40 So it is non -taster.

02:42 It means homozygos excessive.

02:45 Okay.

02:46 The mother had four children, for other children with the following blood types and tasting abilities for ptc.

02:53 The question says, without knowing the father's blood types and tasting ability, then you determine whether the child is really hers.

03:00 Okay.

03:01 And remember that if you, if you have this genotype, for example, okay, for a gene, it means, for example, your mother inherited or your mother transmitted this a allel to you and this b, this b all from your father, okay, or all the way around.

03:21 But your genotype practically reflects the alleles that your mother and your father transmitted to you.

03:29 So, for example, if you have this genotype again, then it means that maybe that one of your parents transmitted you this a, so the genotype for this parent should have at least this.

03:40 This allele and your other parent transmitted you this a lowercase a.

03:46 It means the genotype of this parent should have at least one lowercase a allele.

03:52 So this baby has this genotype.

03:57 So let's apply this to this and let's see if this baby can be like this mother's baby.

04:05 Okay.

04:06 The mother can transmit either o or o.

04:10 So the baby has o, so it has a, so.

04:12 It means it can be like her baby up to now okay the mother has m and n so it means she can transmit either m or n so it also fits so it can be her baby too and now the mother has a staster but we don't know this a little here the baby has two lowercase p two excessive it means she received one p from the father so the father so the father should be should have at least one recessive p and the other p should come from the mother so the mother is heterocygos okay so according to this it also fits so this baby without knowing the genotype of the father can be like this mother's baby okay however we are still not sure out of like 100 % if this mother if this baby is from this mother okay we can calculate it i don't know let's see at the other children that this couple has it says one children has type a type a mn and it is taster okay so the genotype of this child is a space because it can be a or o, mn and taster, and p and small p.

05:46 So this is very important because it is going to allow us to see the genotype of the father and if this baby here is the baby of this mother, okay? so as the mother does not have any o, then the father should transmit this a lead...

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