Why don’t some mutations to a dna sequence have a significant effect on pheonotypic expression?

The reason is that DNA sequences code for certain amino acids. If you look at an amino acid chart there are more than one way to code for certain amino acids. For an example say GGTTA codes for a certain amino acid. But it got changed to GCTTA even though it changed this particular mutation was just another way to code for the same amino acid. So it wouldn't affect the phenotypic expression. It basically is a different way to code for the same things.

it also supports my hypothesis. if you rest first you can squeeze the clothespin more times. from the data i collected the average of the eight people concluded exercise makes your muscles more fatigued and less able to squeeze the clothespin compared to resting before squeezing.

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.