Simulation · Biology · Class 11
Building a protein, level by level
From the lesson Structure of proteins in Biomolecules. Change the values and watch what happens.
Building a protein, level by levelBiology · Class 11
The idea behind it
NCERT §9.7
- Biologists describe protein structure at four levels.
- Primary structure is the sequence of amino acids, the positional information of which comes first, second and so on. The chain is pictured as a line whose left end is the first amino acid, the N-terminal, and whose right end is the last, the C-terminal.
- A protein thread is not a stiff rod. Parts of it coil into a helix, like a spiral staircase, and only right-handed helices are seen in proteins. Other parts fold in other ways. This is the secondary structure.
- The long chain also folds back on itself like a hollow woollen ball. This is the tertiary structure, the three-dimensional view of a protein, and it is essential for many of a protein's biological activities.
- Some proteins are built from several polypeptide chains, called subunits. How these folded subunits sit relative to one another is the quaternary structure.
- Adult human haemoglobin has 4 subunits: two identical alpha subunits and two identical beta subunits.