Final answer:
Homozygosity, gene duplication, inversions and translocations, and nondisjunction can all lead to position effects on gene expression.
Step-by-step explanation:
Position effects on gene expression can occur under certain conditions:
- Homozygosity: When both copies of a gene have the same allele, it can result in altered gene expression patterns.
- Gene duplication: If a gene is duplicated, the extra copies may be located in different genomic regions, leading to position effects on gene expression.
- Inversions and translocations: These chromosomal rearrangements can alter the positions of genes, affecting their expression.
- Nondisjunction: Errors in chromosome segregation during cell division can lead to an incorrect number of chromosomes or imbalances in gene dosage, affecting gene expression.