Which have a greater effect on the sequence of amino acids in a protein a basepair substitution or frameshift?

Question

Which type of mutation would have a greater effect on the sequence of amino acids in a protein a base pair substitution or a frameshift mutation. Explain.

Answer 1

Definitely a frameshift mutation.

A base pair substitution could only merely change a single amino acid. In some cases, this may affect the protein slightly. In other cases, it may not affect it at all, if it changes the third base in a codon which is subject to wobble.

A frameshift, on the other hand, completely changes the protein because it causes every single amino acid after the frameshift protein to be completely different from what it was before. This causes extensive missense or nonsense, because it changes the code for the entire rest of the gene.

For example, let's take the sequence

AUG-AAG-UUU-GGC-UAA
This would normally code for Met-Lys-Phe-Gly-Stop
Now, we have a point mutation:
first case, a substitution. let's substitute a U instead of a C in the second to last codon.
This doesn't change the protein at all, because GGC and GGU both code for glycine. If we change something else, say the first G of the same codon into an A, we replace the amino acid Gly with Ser, a slight change

Now let's look at a frameshift. Say we add an extra C after the first G in teh sequence. now the sequence becomes

AUG-CAA-GUU-UGG-CUA-A
and instead of MetLysPheGly, we get
Met-Gln-Trp-Leu-...

which is completely different.

Answer 2

1

Answer 3

Frame shift by a long ways. Shift your frame and many amino acids are shifted, thus creating a whole new polypeptide chain. A base pair substitution is rather local by definition.

AUCGUAGGC shift that, as you have three triplets. AUC-GUA-GGC to;

UCG-UAG-GC whatever: whole different coding sequence.