Protein Synthesis: Key Concepts and Processes

What are the key concepts and processes involved in protein synthesis?

1. Uncharged amino acids are picked up by tRNA molecules randomly from the cytoplasm and are incorporated into the peptide

2. Unprocessed mRNA is translated into the peptide in eukaryotes

3. Most of the aminoacyl tRNA synthetases contain editing sites in addition to the acylation site

4. Proteins are synthesized in the nucleus and then transported to the cytoplasm for their processing

Answer:

The correct options regarding protein synthesis are:

1. Amino acids are picked up by tRNA molecules in a specific process during protein synthesis.

2. Unprocessed mRNA is not translated in eukaryotes.

3. Proteins are synthesized in the cytoplasm, not the nucleus.

Explanation:

Amino acids are picked up by tRNA molecules and incorporated into the peptide during protein synthesis. However, the picking up of amino acids is not random, but rather a specific process governed by the enzymes called aminoacyl tRNA synthetases. These enzymes ensure that each tRNA molecule is linked to its correct amino acid according to the genetic code.

Unprocessed mRNA is not translated into the peptide in eukaryotes. Before translation, pre-mRNA undergoes various modifications including the addition of a 5' cap and a poly-A tail, and splicing to remove introns.

Proteins are not synthesized in the nucleus. Protein synthesis occurs in the cytoplasm, specifically at the ribosomes located on the endoplasmic reticulum or free in the cytoplasm.