If two recessive lethal alleles come together, they will be expressed and lead to the offspring's death. Let the dominant allele be S and the recessive allele be s. Here, the two individuals are heterozygous for it. So when they mate:
S s
S SS Ss
s Ss ss
1/4 have homozygous fominant genotype (SS), 2/4 have heterozygous genotype (Ss) and 1/4 have homozygous recessive (ss) genotype. Since 1/4 offspring have ss genotype, they will die. Hence, the usual 1:2:1 ratio has been modified here to only 1:2:0
Answer: This is because animals (like humans) have more organelles to store in our bodies than bacteria. This makes sense because without all of our organelles we wouldn't be able to function properly. This is just another one of those form=function things.
