Chapter 11 — LO 6 — Explain What Makes an Allele Dominant or Recessive

How can a functional allele be dominant over a loss-of-function allele?

One functional copy may produce enough protein for the normal phenotype.

Does a dominant allele have to be common or produce more protein?

No. Dominance describes expression in a heterozygote.

What is haplosufficiency?

One functional allele makes enough gene product to support the normal phenotype.

How can a mutant allele act dominantly?

It may gain function, interfere with a normal protein, or reduce functional protein dosage.