How is it that the same tertiary structure of a protein can result from different primary structures? Select one: a. Any protein fold can be achieved under the right conditions (solvent, temperature etc.) b. None of the above c. Primary sequence does not determine tertiary sequence d. Slight differences in primary sequence give the same fold as long as the substitutions are chemically similar (eg. Ile <-> Leu) e. The same fold will be achieved as long as the number of each amino acid is conserved between these differing primary sequences

I believe that the best answer to the question: How is it that the same tertiary structure of a protein can result from different primary structures? Would be, B: None of the above.

Explanation:

This is probably the best choice from all the ones in the list simply because due to specific portions of the other answers they make the statement incorrect.

It will help to remember this: proteins have primary, secondary and tertiary structures because when they first emerge from the trascription process from mRNA, they are a simple string where the most important factor is the sequence of aminoacids. It is this sequence which will determine the folding factor. However, there is another factor that must always be kept in mind; environmental factors (temperature, medium where the protein is, as well as location where it is being produced) will also play a role on how the folding will happen and on which of the aminoacids.

The evolvement of a protein chain from its primary, to its secondary and then tertiary shape (the only functional, or known as native state) depends on which of the aminoacids in a specific sequence has the necessary elements to form bonds (hydrogen bonds) with others and thus start the folding process.