What process involves the expression of only one copy of a gene in an individual while suppressing the other?

The process that involves the expression of only one copy of a gene while suppressing the other is known as imprinting. Genomic imprinting is a form of epigenetic regulation where certain genes are expressed in a parent-of-origin-specific manner. This means that for imprinted genes, one allele is transcriptionally active while the other is silenced, often due to methylation or other chemical modifications to the DNA. This selective gene expression can lead to phenotypic differences even in the presence of two copies of the gene, showcasing how genetic regulation can influence traits based on parental origin.

In contrast, dominance refers to the interaction between alleles where one allele masks the expression of another in a heterozygous state but does not involve the specific suppression of one copy based on parent origin. Epistasis describes interactions between different genes where the presence of one gene can mask or modify the expression of another gene, rather than focusing on individual alleles. Crossing over is a process that occurs during meiosis where genetic material is exchanged between homologous chromosomes, increasing genetic diversity, but it does not relate to the expression suppression of a single gene copy.