Final answer:
A position effect occurs when a gene's expression is altered due to a change in its position, which can happen with inversions and translocations. Epistasis is another phenomenon where genes can interact at the level of gene products.
Step-by-step explanation:
A position effect occurs when a gene's expression is altered due to a change in its position. This can happen as a result of inversions and translocations. Inversions involve the detachment, 180° rotation, and reinsertion of part of a chromosome, which can change the orientation of genes. Translocations involve the rearrangement of chromosome segments, which can also affect gene expression. For example, altered gene orientation can result in functional changes because regulators of gene expression could be moved out of position with respect to their targets, causing aberrant levels of gene products.
Epistasis is another phenomenon that can occur when genes interact at the level of gene products, where the expression of one gene may mask or modify the expression of another gene. This can further influence gene expression.