Protein synthesis takes place inside cells - OCR Gateway - GCSE Biology - Question 22 - 2020 - Paper 1

Protein synthesis is the process by which cells create proteins from amino acids, following the instructions encoded in DNA. The process involves several key steps:

1. Transcription: Within the nucleus, a specific segment of DNA unwinds, and messenger RNA (mRNA) is synthesized based on one of the DNA strands. This mRNA serves as a template that carries genetic information from DNA to the ribosomes.

2. mRNA Processing: Before the mRNA exits the nucleus, it undergoes modifications such as splicing. This prepares it for translation by removing non-coding regions.

3. Translation: The mature mRNA moves to a ribosome, the cellular machinery located in the cytoplasm where protein synthesis occurs. Here, the ribosome reads the sequence of nucleotides in the mRNA in groups of three, known as codons.

4. Role of Transfer RNA (tRNA): Each codon on the mRNA is matched with its corresponding amino acid, brought to the ribosome by transfer RNA (tRNA) molecules. The tRNA has an anticodon that is complementary to the mRNA codon.

5. Peptide Bond Formation: As the ribosome moves along the mRNA, amino acids are linked together by peptide bonds, forming a polypeptide chain. This chain eventually folds into a functional protein.

In summary, protein synthesis is a complex process involving the transformation of genetic information into functional proteins through transcription and translation, utilizing amino acids as the building blocks.