why should nucleotides be in proper sequence during protein synthesis?
Nucleotides should be in the proper sequence during protein synthesis because the sequence of nucleotides in DNA determines the sequence of amino acids in a protein. Proteins are synthesized by a process called translation, which involves the translation of the genetic information stored in DNA into a functional protein.
Here's an explanation of how nucleotide sequence determines protein sequence during protein synthesis:
1. Transcription: The first step is the transcription of DNA into RNA. RNA polymerase enzyme reads the DNA sequence and synthesizes an RNA molecule, called messenger RNA (mRNA), which is complementary to one strand of the DNA.
2. mRNA processing: The newly formed mRNA undergoes various modifications, such as the removal of introns (non-coding regions) and addition of a cap and a tail to protect it from degradation.
3. Translation: The mRNA is then transported out of the nucleus and into the cytoplasm, where it interacts with ribosomes, the protein-making machinery. The ribosome reads the mRNA sequence in groups of three nucleotides at a time, called codons.
4. Genetic code: The sequence of nucleotides in the mRNA forms a code that determines the specific amino acids that will be incorporated into the protein. Each codon codes for a specific amino acid, except for a few codons that indicate the start or stop of protein synthesis.
5. Amino acid assembly: Transfer RNA (tRNA) molecules, with their specific anticodon sequences, recognize and bind to the codons on the mRNA. Each tRNA molecule carries the corresponding amino acid for the codon it recognizes.
6. Peptide bond formation: The ribosome joins the amino acids carried by the tRNA molecules together, forming a polypeptide chain. The sequence of codons in the mRNA determines the order in which amino acids are added, thus determining the primary structure of the protein.
7. Protein folding: The polypeptide chain undergoes folding and further processing to form its functional three-dimensional structure. The final shape of the protein determines its function in the cell.
If the nucleotides are not in the proper sequence, it can lead to errors in the sequence of codons, resulting in the production of a non-functional protein or even a completely different protein. Therefore, the correct sequence of nucleotides is crucial in ensuring the proper functioning of the protein being synthesized.