1. Frameshift Mutation: This is the most likely outcome. The reading frame of the genetic code is shifted, changing every codon from that point onward. Imagine reading a sentence where a letter is removed: the meaning changes dramatically.
2. Consequences:
* Premature Stop Codon: The frameshift often introduces a stop codon (UAA, UAG, or UGA) sooner than expected. This leads to a truncated protein, often non-functional.
* Altered Amino Acid Sequence: Even if a stop codon isn't immediately introduced, the frameshift changes the amino acid sequence after the deletion. This can dramatically alter the protein's structure and function.
* Loss of Function: The protein is likely to lose its normal function, as the altered amino acid sequence disrupts its folding, stability, or ability to interact with other molecules.
* Gain of Function: In rare cases, the frameshift might result in a protein with a new function, though this is less common.
Example:
Let's say a coding sequence originally reads:
```
AUG GCU UAC AGC GGA UAA ...
```
This codes for the amino acids: Met - Ala - Tyr - Ser - Gly - Stop
If the "C" in the third codon is deleted, the sequence becomes:
```
AUG GCU UAG CGGA UAA ...
```
Now, the reading frame is shifted. The new codons are:
* AUG (Met)
* GCU (Ala)
* UAG (Stop)
The protein will be truncated after only two amino acids, instead of the original six.
In summary, the loss of a single nucleotide pair from the middle of a coding sequence is a serious mutation. It typically leads to a frameshift, resulting in a non-functional or altered protein. This can have significant implications for the organism's health and development.
