CRISPR & Genome Editing Flashcards
(15 cards)
What is CRISPR and what does it stand for?
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. It refers to DNA sequences in bacteria that function as part of their adaptive immune defense.
What biological function does CRISPR serve in prokaryotes?
It allows bacteria to “remember” viral DNA by storing it as spacers, and use RNA guides to target and destroy future viral invaders.
Who first demonstrated CRISPR as a programmable gene-editing tool and when?
Jennifer Doudna and Emmanuelle Charpentier in 2012.
What are the components of the CRISPR-Cas9 system?
Cas9: An endonuclease that cuts DNA
crRNA: CRISPR RNA with sequence matching target DNA
tracrRNA: Trans-activating RNA that pairs with crRNA to form a guide
PAM: Protospacer Adjacent Motif (e.g. NGG) – essential for Cas9 to bind and cut
What is the role of the PAM sequence?
It allows Cas9 to recognize and bind DNA adjacent to the target sequence. Without PAM, Cas9 will not cut.
How is a guide RNA (gRNA) designed for CRISPR editing?
The gRNA is made complementary to a 20-base pair target DNA sequence upstream of a PAM site (typically NGG), directing Cas9 to the specific location.
Describe the three major steps in CRISPR-Cas9 gene editing
Targeting: gRNA binds to complementary DNA next to PAM
Cutting: Cas9 creates a double-strand break
Repair: Cell repairs DNA via either NHEJ (non-homologous end joining) or HDR (homology-directed repair)
What’s the difference between NHEJ and HDR in CRISPR editing?
NHEJ: Error-prone, often causes gene knockout via frameshift mutations
HDR: Uses a donor template to precisely edit or insert new genetic material
Name three major applications of CRISPR in biotechnology.
Gene therapy (e.g. sickle cell disease)
Agricultural modification (e.g. disease-resistant crops)
Functional genomics research
What are some limitations or risks of CRISPR?
Off-target effects
Ethical issues in germline editing
Delivery challenges in human cells
Who are the two main groups involved in the CRISPR patent dispute?
Jennifer Doudna & Emmanuelle Charpentier vs. Feng Zhang (Broad Institute)
What is the core issue of the CRISPR patent war?
Whether the original CRISPR invention by Doudna/Charpentier applied to eukaryotic cells. Broad filed separately and secured patents for eukaryotic (human) use.
What was the 2020 USPTO ruling regarding CRISPR patents?
The Broad Institute retained its patents for use of CRISPR in human cells, though litigation is still ongoing.
Why is germline editing controversial in CRISPR use?
Changes made to embryos affect future generations and raise concerns about consent, inequality, and unintended consequences (e.g. “designer babies”).
What’s one high-profile ethical scandal involving CRISPR?
In 2018, Chinese scientist He Jiankui created the first gene-edited babies, claiming to knock out CCR5 to confer HIV resistance—sparking international backlash and legal consequences.
