Pedigrees are used to help geneticists understand how traits are inherited between generations. The Romanovs, a Russian royal family, had a history of hemophilia, a sex-linked disorder that is determined by a recessive allele on the X chromosome.
What is the best evidence to prove that Irene was heterozygous for hemophilia?
Alice has the recessive allele.
Alexandra has the recessive allele.
Frederick has the recessive allele.
Waldemar has the recessive allele.
In the pedigree it is shown that Alice passes the gene to Irene. Which is also a haemophiliac. Irene is a female and hemophilia can determined by recessive allele on the X chromosome. So if only one of the allele is recessive for haemophilia in the allelic pair than the condition will be heterozygous as only one allele is responsible to cause haemophilia in females. This is why Irene is heterozygous for haemophilia.
The best evidence to prove that Irene was purebred for hemophilia is Alice has the recessive allele.
What is a recessive allele?
The maximum not unusual place interplay among alleles is a dominant/recessive relationship. An allele of a gene is stated to be dominant whilst it efficiently overrules the other (recessive) allele. Eye shade and blood companies are each examples of dominant/recessive gene relationships.
Hemophilia A and hemophilia B are inherited in an X-related recessive pattern. The genes related to those situations are positioned at the X chromosome, that is one of the chromosomes. In males (who've handiest one X chromosome), one altered reproduction of the gene in every cell is enough to reason the condition.
