What is the purpose of meat tenderizer in dna and rna lab?

 Meat tenderizers contain proteases, which are enzymes that break down proteins. In meat, they break down the proteins that make up muscle, softening the meat in the process. 

In DNA extraction, they break down the protein core, called a histone, that the DNA is supercoiled around. It's the supercoiling that allows a few meters worth of DNA to be compacted into a microscopic structure, and it also plays a role in gene regulation. 

To a lesser extent, the proteases in the tenderizer can break down DNase enzymes (since enzymes are proteins too), which chop up DNA (to protect the cell from some viruses). Normally, the DNase is kept separate from the cell's DNA, but when you add detergent to the cells and break apart the membranes, all of the components can mix together and lead to unintended reactions. 

When you break down the histone proteins, the DNA uncoils and stretches out, allowing you to see it and wind it around a stick (if your extraction protocol includes that step).