What does the term "cis-acting" refer to in genetics?

The term "cis-acting" refers to elements that affect only the same molecule of DNA in which they are located. These elements include sequences such as promoters, enhancers, and silencers that regulate gene expression by interacting with the transcription machinery or other local factors on the same DNA molecule.

Cis-acting elements are crucial because they can influence the transcription of neighboring genes on the same strand, allowing for the regulation of those specific genes without affecting others that are located on different molecules or chromosomes. This specificity is essential for fine-tuning gene expression in a localized manner.

The other concepts mentioned in the choices do not align with the definition of cis-acting elements. For example, elements that act on distant genes would be considered trans-acting, while those that encode proteins refer to coding sequences, which are also separate from the regulatory roles of cis-acting elements. Similarly, cis-acting elements do not inherently require trans-acting factors, although their activity can be influenced or facilitated by such factors, such as transcription factors that bind to them.