This is the DNA. I'm going to only use the upper strand to demonstrate what this strand would code for before and after a single bp deletion (so write it as mRNA). I will also write it how it's easier to see this which is to split them up into the 3 base codon system. Note that you don't need to know the amino acid code - you use a table to find these.
ORIGINAL (mRNA on top, Amino Acid (AA) on bottom:
5'-AGC GGG AUG AGC GCA UGU GGC GCA UAA CUG-3'
SER GLY MET SER ALA CYS GLY ALA STOP LEU
Note that the protein would stop being made at the stop codon and the LEU wouldn't matter at the end...
Now, I will remove one bp...(I bolded it up top). Rewrite the mRNA and find the corresponding AA...
NEW
5'-AGC GGG AUG GCG CAU GTG GCG CAU AAC UG-3'
SER GLY MET ALA HIS VAL ALA HIS ASN .....
Completely different amino acid sequence after the methionine (MET). The stop codon is gone...the protein would continue being translated until it reaches another stop codon...so not what was supposed to be made!
