Polypeptide modification can convert an inactive precursor into a functional protein through cleavage, folding or chemical processing after translation in cells.
Coverage 2016–2016 · Updated 16 Jul 2026
New polypeptides can be folded, cleaved or chemically modified after translation before becoming functional proteins.
Processing can expose an active site, add a targeting group, join subunits or alter stability. The final protein depends on sequence and post-translational handling.
Name: initial chain; processing event; structural change; functional consequence.
A precursor protein can be cleaved to remove a signal segment and reveal the mature active form.
Translation ending does not guarantee a functional protein; folding and processing may still be required.
This objective is assessed through structured response, commonly using Suggest.
Suggest
Build the answer around this relationship: A newly translated polypeptide may be an inactive precursor.
Representative question
Insulin is produced by cutting C -peptide from the precursor molecule proinsulin. Suggest why group 1 has a greater level of C-peptide than group 2.
RNA polymerase reads template DNA 3' to 5' and synthesizes RNA 5' to 3'; ribosomes translate mRNA codons in the 5' to 3' direction. Promoters mark transcription start regions and orientation; transcription factors help RNA polymerase bind and initiate in eukaryotes. Non-coding DNA does not code for polypeptide amino acid sequences and includes introns, regulatory sequences, telomeres, rRNA genes, and tRNA genes. Eukaryotic pre-mRNA is modified before export and translation by adding a 5' cap and poly-A tail and removing introns by splicing. Alternative splicing joins different exon combinations from one pre-mRNA, so one gene can produce multiple protein variants in different cells or stages. Translation initiation assembles ribosomal subunits at the start codon AUG; initiator tRNA enters the P site and A, P, and E sites organize tRNA movement. Newly made polypeptides may be folded, cleaved, or chemically modified; preproinsulin processing to active insulin is a key example. Proteasomes degrade tagged, damaged, or unneeded proteins; amino acid recycling supports new protein synthesis and proteome quality control.
