Topic content:
There are both dominant mutations (A) and recessive mutations (a) in the β - globin gene (A+) on the human autosome, which can lead to thalassemia. A couple both suffering from thalassemia gave birth to a normal child. The possible genotype combinations of this couple are
A. 1
B. 2 kinds
C. 3 kinds
D. 4 kinds
Best answer:
C
Answer analysis:
There is no explanation for this question
Test core:
Genotype and phenotype:
1. Manifestation: refers to the traits shown by individual organisms, such as the high stem and short stem of pea.
2. Genotype: gene composition related to phenotype, such as DD or Dd for high stem pea and dd for dwarf pea.
3. Allele: A gene that controls a relative trait.
4. Homozygote: A zygote formed by the union of two gametes with the same genotype, and a new individual developed from the zygote. For example, individuals with genotype AAbb, XBXB and XBY are homozygous. There is no allele in the gene composition of homozygote, and only one genotype of gamete (female gamete or male gamete) can be produced. Self bred offspring have no sexual segregation.
5. Heterozygote: A zygote formed by the union of two gametes with different genotypes, and a new individual developed from the zygote. For example, individuals with genotype AaBB and AaBb. The gene of the heterozygote consists of at least one right allele, so at least two types of gametes (female gametes or male gametes) can be formed, and character segregation occurs in self bred offspring.