What hypotheses have been proposed to explain how prions evolve? Select the TWO answers that are correct.

a. When the environment changes, one of the less common variants in a prion population may be able to better spread and become the dominant type of prion.

b. Prions respond to environmental changes by bonding with other prion variants in the population and potentially forming new variants able to handle the change.

c. Changes in the environment change the shape of some prions, possibly producing a variant that is better able to tolerate the change than the original type of prion.

d. Environmental changes cause some prions to break into small segments that may be better able than larger prions to survive and reproduce in the new environment.

b. Prions respond to environmental changes by bonding with other prion variants in the population and potentially forming new variants able to handle the change.

d. Environmental changes cause some prions to break into small segments that may be better able than larger prions to survive and reproduce in the new environment.

Explanation:

The first hypothesis that tried to explain how prions replicate in a protein-only manner was the heterodimer model. This model assumed that a single PrPSc molecule binds to a single PrPC molecule and catalyzes its conversion into PrPSc. The two PrPSc molecules then come apart and can go on to convert more PrPC.

prion hypothesis states that the misfolded prion protein, rather than virus or bacteria, is the infectious agent that results in the transmission of prion disease.