This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transcription, Subject name: Biochemistry
Promoter sequence is an example for 
Select and explain. 
A. Cis acting factor, B. Trans acting factor, C. Coactivator, D. Mediator
A: Cis acting factor
Answer: A: Cis acting factor 
Explanation: Trans acting factors control the expression of cis-regulatory element Cis-regulatory elements are DNA sequences present on the same molecule of DNA (chromosome) as the gene they regulate. E.g. Promoter is a cis-regulated element usually located upstream of the transcribed region. Enhancers are cis-regulatory elements that can be located upstream, downstream, within the introns,