A dominant negative mutation affects protein shapes when they bind to one another to form dimers. What allele acts as if it is 'dominant'? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Obviously the dominant allele, since that is where it gets it name from! b Both the dominant allele and the recessive allele act 'dominant' and are fully functional, which makes this mutation the same as codominance. c Strangely, the heterozygous condition is dominant since this condition is based on protein dosage. d tati... The recessive allele acts 'dominant', which is indicated by the addition of the word 'negative' since it affects both the double recessive condition and the heterozygous condition