Question

Describe the techniques used to determine whether a mutation is recessive or dominant

Answer 1

1. Pedigree analysis- By reading a pedigree chart one can determine whether the trait is domainant or recessive. It shows if the condition is autosomal or sex linked disorder. For example in an x linked recessive traits males are commonly more affected than females. Its an important tool for determining human inherited diseases. Its constructed with standarized symbols and includes information about the disease status of each individual.

When the mutation is not detectable genetic linkage studies can help. These label the chromosme around gene and track the segment of chromosome through individuals in different generations in family. Unusual phenotype of recessive disorder is determined by homozygosity for a recessive allele and the unaffected genotype is determined by dominant allele. in autosomal dominant disorders norml allele is recessive and abnormal allele is dominant.

2. Complementation test- its another for determining whether mutations in 2 strains are in different genes. (mutation can occur in the same gene, one mutation affects the expression of another, one mutation may result in an inhibitory product) complementation wont occur if mutation are on the same gene.

3. epistasis- in this mutation in 1 gene masks the expression of different gene. In the case of dominance one allele of a gene masks the expression another allele of same gene and for example in complete baldness the mutation that causes it would be epistatic to a mutant gene that determines its color of hair.