Helicase Hijinks

Geneticist’s pick-up line: I wish I were DNA Helicase so I could unzip your genes.

Okay, it’s slightly off-color, but hopefully not too offensive. As an actual pick-up line, I give it about one chance in ten of succeeding; in the right setting, with the right person, you might do all right.

Being a living organism is hard work. You need a specific set of materials to keep you ticking. You must consume some of those materials from the environment, such as oxygen and food. Other materials are manufactured inside your cells, which requires specialized molecular machinery. Each of your cells has a full set of instructions telling it how to build and operate this machinery. These instructions are known as genes.

A human cell contains between 30,000 and 40,000 genes. Each gene is made of a strand of DNA (DeoxyriboNucleic Acid). You’ve probably seen a model of DNA before. It vaguely resembles a twisted ladder, like this:

The rungs of DNA are quite different from the rungs of a real ladder in that they are not continuous across the width of the ladder. The rungs are actually in two pieces, held together in the middle by a force called hydrogen bonding. When your cells divide, each gene must be copied so that both daughter cells receive the complete set of instructions. This requires “unzipping” the DNA molecule, which in turn requires breaking the hydrogen bonds that hold its halves together.

The process of unzipping DNA is achieved by a special enzyme called DNA helicase. An enzyme is a protein manufactured by your cells to perform specific functions. DNA helicases (there’s more than one type) “crawl” along the length of a DNA molecule, breaking its hydrogen bonds and separating it into two separate strands. Two new strands are then built from the templates of the original strands.

In this video, Hank Green talks about the structure, history, and replication of DNA. He describes the role of DNA helicase in unzipping DNA strands, and he tells a version of this joke. It’s all fascinating but if you want to jump straight to the replication discussion, it starts at 8:50.

DNA helicase is also used in a process called transcription, which is where the DNA code is transferred into single-stranded RNA (RiboNucleic Acid) segments. These RNA chains are then shipped to the cell’s manufacturing district for further processing. Just as in replication, the double-stranded DNA must be unwound and unzipped so the RNA can be built from its template.

So whether you’re replicating or transcribing, if you need help unzipping your genes DNA helicase is your enzyme.


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