Final answer:
The process of learning about genotypes by studying mutant phenotypes is called forward genetics, where scientists start with a phenotype and identify the underlying gene mutations.
Step-by-step explanation:
The process of learning about genotypes by studying mutant phenotypes is called forward genetics.
In forward genetics, scientists start with a mutant phenotype and work backwards to identify the genetic basis responsible for that trait. This approach contrasts with reverse genetics, where researchers begin with a known DNA sequence and investigate its function by observing the phenotype changes resulting from the genetic manipulation. Classic genetics looked for genes responsible for a phenotype, often through mutation or cross-breeding experiments. By observing inherited traits, like those discovered by Gregor Mendel in pea plants, geneticists inferred genotypes. Mendel's laws, such as the law of independent assortment and the law of segregation, helped establish the principles behind these traits' inheritance. Forward genetics has played a crucial role in understanding genetic disorders and inheritance patterns by looking at phenotypic expressions (observable traits) of altered or mutant genes.