A random base change is less likely to affect phenotype in humans than in bacteria. Why? Please select all that apply.

Question

Quizplus · Accepted Answer

Humans have two copies of the genome (diploid) so a change could occur in a recessive allele and there may be no effect on phenotype. Bacteria only have one copy (haploid), so the function of a damaged gene cannot be replaced by that of another allele. More of the bacterial genome consists of genes and is functional than in the human genome. This means that any random change is more likely to occur at an important position in bacteria than in humans. Finally, changes at the third base of a codon are less likely to be damaging than changes at positions 1 and 2, but third base changes are no more likely to occur in bacteria than in humans.
Random changes that do not confer a reproductive advantage or disadvantage are selectively neutral.

A Random Base Change Is Less Likely to Affect Phenotype