Cis and Trans Acting Elements/Sites

[rockind78]

I am a bit confused I guess about exactly what these are. If anyone could offer up an example of each, I would be very grateful. I did find this much:

http://cancerweb.ncl.ac.uk/cgi-bin/omd?query=cis+acting

 

[iansmith]

Monique ask the same question in this thread
https://www.physicsforums.com/showthread.php?s=&threadid=9011&highlight=cis+trans

Basically, cis is an element that is on the same DNA molecules and trans is something on a different molecules.

Best example is with the lac operon. In wild type strain, LacI and lacO are cis acting elements. If you knock-out lacI and complement the defective strain with a plasmid carrying lacI. The lacI on the plasmid is an example of a trans acting element.

 

[ravenprp]

Sure, let me try to clarify the concept of cis and trans acting elements/sites for you. These terms refer to specific DNA sequences that play a role in gene regulation.

Cis-acting elements are DNA sequences that are located on the same chromosome as the gene they regulate. They are typically found in the promoter region of a gene and can interact with transcription factors to either enhance or repress gene expression. An example of a cis-acting element would be the TATA box, which is a sequence of nucleotides found in the promoter region of many genes and is involved in the binding of RNA polymerase.

On the other hand, trans-acting elements are regulatory factors that are encoded by genes located on different chromosomes from the gene they regulate. These factors can bind to specific cis-acting elements on the DNA and influence gene expression. An example of a trans-acting element would be a transcription factor, such as the estrogen receptor, which can bind to specific DNA sequences and activate or repress gene expression.

To summarize, cis-acting elements are DNA sequences located on the same chromosome as the gene they regulate, while trans-acting elements are regulatory factors encoded by genes located on different chromosomes. Both types of elements work together to control gene expression and play important roles in various biological processes. I hope this helps!