Question bank: Basic Genetics

Pedigrees are useful in identifying genetic diseases that can be passed from parents to children. For example, albinism is a genetic disease caused by mutations in the melanin gene, responsible for skin, hair, and eye pigmentation. Albinism is characterized by which symptoms?

In a controlled breeding experiment in a plant species, it was observed that the flower color trait followed an inheritance pattern of a gene with two alleles, where allele A determined the red color and allele a the white color. A biologist performed a cross between two plants heterozygous for this trait, that is, with genotypes Aa. During meiosis, independent segregation of another pair of alleles was observed, which determined the presence of thorns on the leaves, with allele B responsible for thorny leaves and allele b for smooth leaves. Knowing that a plant's genotype can influence factors beyond external appearance, such as resistance to certain diseases, and that the presence of thorns is a dominant trait, answer items a and b below.

In a science class, we discussed the genetic inheritance of a blood group. Considering that a couple plans to have a child and both parents know that the father has blood type AB, while the mother has blood type O, and we want to determine the probability of the child inheriting blood group AB.

In a family, the father has blood type A and the mother has blood type B. They want to know the probability of each possible blood type for their children, considering that blood transfusion is only compatible between individuals with the same blood type or with type O, which is the universal donor. Based on the knowledge of genetic inheritance of blood types, answer: (1) What is the most common blood type expected for the children of this couple and what is the probability of a child inheriting this blood type? (2) Explain briefly how Mendel's genetics applies in this specific case.

In a genetics experiment, a couple plans to have children and decides to investigate the probability of a child being born with a specific blood type. The father is heterozygous for the ABO system, meaning he has an allele for blood type A (IA) and an allele for blood type B (IB). The mother is homozygous for blood type O (ii). The ABO system is determined by a locus with multiple alleles, where IA and IB are co-dominant and both dominate the i allele, which is recessive and determines blood type O. Write a paragraph briefly explaining how alleles combine to determine blood types in the ABO system, and then calculate the probability that the couple's first child will be born with blood type A. Consider that meiosis and fertilization occur without genetic recombination and that the child's sex does not influence the blood type outcome.