After collecting the required data, we need interpret whether the pedigree chart of my family with the single controlled gene character of rolling the tongue is autosomal or X-linked.
If the disorder is X-linked most of the males will have the disorder because the Y-chromosome cannot mask the affects of an affected X-chromosome. A female can have the disorder, but it would be a very low percentage. For a female to be affected, she would have had to receive an affected gene from the mother and the father. This means that the father would have the disorder and the mother was a carrier.
In an autosomal disorder, the disorder is not found on the X or Y chromosome. It is found on the other 22 chromosomes in the human body. This means that men and women have an equal chance of having the disorder. The mother and father can be homozygous dominant, heterozygous, and homozygous recessive. If a person is homozygous dominant, the person has two of the same dominant genes.
The second step is to determine if the disorder is dominant or recessive. It is important to find out if a disorder is dominant or recessive.
If a disorder is dominant, one parent must have the disorder (either homozygous dominant (TT) or heterozygous recessive (Tt). Both parents do not have to have the disorder. One parent might not have the disorder or be a carrier. If a disease is dominant, it does not skip a generation unless one parent is heterozygous dominant (Tt) and the other parent is homozygous recessive (tt). In this case the child has a chance of not receiving the dominant gene.
If the disorder is recessive, a parent does not have to have the disorder, but could still pass it to their offspring. This would happen when a parent is heterozygous recessive (Tt) and passes on the recessive (t) gene. This means this disorder can skip generations. An example of a recessive disorder would be sickle cell anemia.
- DATA PROCESSING AND PRESENTATION:
Predicting possible phenotypes and genotypes:
- Fathers Family
Let:
B= Tongue rolling , b= No tongue rolling
Grandmother × Grandfather
Parents: bb Bb
Gametes: b B b
*BY USING A PUNNET GRID, WE CAN PREDICT THE OFFSPRING OF THE GENETIC CROSSES
Punnet Square:
Genotype: Bb , bb
Phenotype: Able to roll tongue Unable to roll tongue
- Mothers Family
Let:
B= Tongue rolling , b= No tongue rolling
Grandmother × Grandfather
Parents: Bb bb
Gametes: B b b
*BY USING A PUNNET GRID, WE CAN PREDICT THE OFFSPRING OF THE GENETIC CROSSES
Punnet Square:
Genotype: Bb , bb
Phenotype: Able to roll tongue Unable to roll tongue
- My Family
Let:
B= Tongue rolling , b= No tongue rolling
Mother × Father
Parents: Bb Bb
Gametes: B b B b
*BY USING A PUNNET GRID, WE CAN PREDICT THE OFFSPRING OF THE GENETIC CROSSES
Punnet Square:
Genotype: BB , Bb , Bb , bb
Phenotype: Able to roll tongue Able to roll tongue Able to roll tongue Unable to roll tongue
Based on the above Punnet Square, my genotype could not be predicted. The genotypic ratio is 3:1, meaning that three have the ability to roll their tongue and 1 does not. My genotype could be in the form of BB or Bb, but this could not be known until my offspring’s are present.
Family Genetic Pedigree of three generations representing a one gene controlled character, tongue rolling.
