Of the following mutations, ____ is likely most deleterious, and ____ is likely least deleterious.   A table of the genetic code is shown below.  1. A change from TCA to TCG near the beginning of the open reading frame  2. A change from TAC to TAA near the beginning of the open reading frame  3. The insertion of an A near the end of the open reading frame  4. A change from TCT to CCT near the middle of the open reading frame

To answer this question, we need to understand what each of these mutations does to the genetic code.

1. A change from TCA to TCG: This is a silent mutation. Both TCA and TCG code for the amino acid Serine. Therefore, this mutation is not likely to be deleterious.

2. A change from TAC to TAA: TAC codes for the amino acid Tyrosine, while TAA is a stop codon. This mutation would cause the protein to stop being synthesized prematurely, which could be very deleterious, especially if it occurs near the beginning of the open reading frame.

3. The insertion of an A near the end of the open reading frame: This is a frameshift mutation. It would cause all of the codons after the insertion to be read incorrectly, potentially altering many amino acids in the protein. However, since it occurs near the end of the open reading frame, it might not be as deleterious as a frameshift mutation occurring earlier in the sequence.

4. A change from TCT to CCT: TCT codes for the amino acid Serine, while CCT codes for Proline. This is a missense mutation, which changes one amino acid in the protein. The effect of this mutation would depend on the importance of the changed amino acid to the protein's function.

Based on this analysis, the mutation from TAC to TAA near the beginning of the open reading frame is likely the most deleterious, as it would cause the protein to stop being synthesized prematurely. The least deleterious is likely the change from TCA to TCG near the beginning of the open reading frame, as this is a silent mutation that does not change the amino acid sequence of the protein.