Question

One gene in the human genome may be expressed at a much higher level than another. Can differences in types of cis elements present account for this

Answer 1

No, CREs usually don't account for differences in gene expression levels.

Step-by-step explanation:

Cis-regulatory elements (CREs) are non-coding DNA regions that regulate adjacent gene transcription. They usually do it by binding to transcription factors. They are in charge of influencing the rate of which transcription occurs, and less with how much a gene is expressed. On the other hand, trans-regulatory elements are DNA sequences that encode for upstream regulators that can modify or regulate gene expression levels.

Therefore, cis elements are not really in charge of expression levels, mostly transcription rates of single genes, rather. Trans elements are more involved in expression levels.