Which of these statements about protein synthesis are NOT correct ?
I. During transcription, mRNA synthesized from DNA nucleotides to have the same sequence of nucleotides as the DNA strand on which it was made.
II. During transcription , tRNA is synthesized from RNA nucleotides and carries codons that are complementary to the sequence of nucleotides on the DNA strand on which it was made.
III. During translation, mRNA is synthesized from RNA nucleotides to have the complementary sequence of nucleotides to that. Of the DNA strand on which it was made .
IV. During translation ribosomes move on mRNA from '5' and '3' one codon at a time .This is called translocation

Options

A. I,II and III only
B. I,II ,III and IV
C. III and IV only
D. I, II and IV only

Answer

To determine which statements about protein synthesis are NOT correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement I**: "During transcription, mRNA synthesized from DNA nucleotides to have the same sequence of nucleotides as the DNA strand on which it was made."
- **Analysis**: This statement is incorrect. During transcription, mRNA is synthesized from the DNA template strand, and it has a sequence that is complementary to the template strand, not identical. The coding strand of DNA has the same sequence as the mRNA (except for uracil in RNA replacing thymine in DNA), but the template strand does not.
- **Conclusion**: Statement I is NOT correct.

2. **Statement II**: "During transcription, tRNA is synthesized from RNA nucleotides and carries codons that are complementary to the sequence of nucleotides on the DNA strand on which it was made."
- **Analysis**: This statement is also incorrect. tRNA is not synthesized during transcription; instead, it is involved in translation. tRNA carries amino acids to the ribosome and has anticodons that are complementary to the codons on the mRNA, not directly to the DNA.
- **Conclusion**: Statement II is NOT correct.

3. **Statement III**: "During translation, mRNA is synthesized from RNA nucleotides to have the complementary sequence of nucleotides to that of the DNA strand on which it was made."
- **Analysis**: This statement is incorrect. mRNA is synthesized from DNA during transcription, not translation. During translation, the ribosome reads the mRNA to synthesize proteins. Therefore, this statement confuses the processes of transcription and translation.
- **Conclusion**: Statement III is NOT correct.

4. **Statement IV**: "During translation, ribosomes move on mRNA from '5' to '3' one codon at a time. This is called translocation."
- **Analysis**: This statement is correct. During translation, ribosomes do move along the mRNA in the 5' to 3' direction, reading one codon at a time. The process of the ribosome moving from one codon to the next is indeed called translocation.
- **Conclusion**: Statement IV is correct.

### Final Conclusion:
The statements that are NOT correct are:
- I
- II
- III

Thus, the answer is that statements I, II, and III are NOT correct.