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Chopped! Using CRISPR/Cas9 to cut DNA - Student's Guide
Version: 1.0 - Release: May 2022 - © 2022 by miniPCR bio™
Student's Guide
P./12
Background information
Overview
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The introduction of CRISPR/Cas9 into the biotechnology toolkit has revolutionized scientists' ability
to manipulate DNA in living organisms. In today's lab, you will use the CRISPR/Cas9 system in vitro
(in a test tube) to break down exactly how the different parts of this gene targeting system work.
CRISPR/Cas9: a powerful tool
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Typically, an organism's DNA sequence doesn't change over its lifespan. But sometimes scientists
want to change the DNA within the cells of a living organism. For example, they may wish to
investigate how certain genes work or correct mutations that cause genetic disease. Making specific
changes to DNA inside living cells is called genome editing, and developing reliable genome editing
tools has been the goal of scientists for decades.
Until recently, the methods used to perform genome editing could only be applied to a few model
organisms such as mice. Furthermore, these genome editing tools were generally inefficient and
difficult to use. That changed in 2012 with the introduction of the CRISPR/Cas9 system. The CRISPR/
Cas9 system provided a universal method to make targeted changes to almost any DNA sequence
in virtually any organism. This proved revolutionary both for scientists trying to understand the
functions of genes and for clinical researchers seeking to treat genetic diseases.
To understand why CRISPR/Cas9 is such a versatile system, we need to look at its individual
components and understand how they work at the molecular level.
Using CRISPR/Cas9 as a genome editing tool
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Scientists did not invent the CRISPR/Cas system from scratch; like most biotechnology tools, it has a
natural origin. CRISPR/Cas is found naturally in bacteria and archaea where it plays a role in immune
function, providing protection from harmful viruses. Scientists have repurposed this bacterial
immune system as a genome editing tool because it allows them to target specific DNA sequences
with relative ease.
The Cas in CRISPR/Cas refers to an enzyme known as the Cas nuclease. A nuclease is an enzyme
that cuts nucleic acids, such as DNA, like a pair of molecular scissors. There are actually several
