[W10] Genome editing with CRISPR- Cas Flashcards
(31 cards)
What does CRISPR stand for?
Clustered Regularly Interspaced Short Palindromic Repeats
What is the natural role of CRISPR-Cas systems?
Adaptive immune systems in prokaryotes that defend against viruses and plasmids
How is CRISPR used in molecular biology?
As a tool for precise genome editing in cells and organisms
What are the three stages of the CRISPR-Cas immune response?
Adaptation, Expression, Interference
What occurs during the Adaptation stage of CRISPR immunity?
Insertion of invader DNA (spacer) into CRISPR array
What occurs during the Expression stage of CRISPR immunity?
Transcription of CRISPR array into pre-crRNA and maturation into crRNAs
What occurs during the Interference stage of CRISPR immunity?
crRNA guides Cas proteins to degrade matching foreign DNA
What is a protospacer?
A foreign DNA sequence that matches a spacer in the CRISPR array
What is a PAM?
Protospacer Adjacent Motif – a short DNA sequence required for Cas9 to recognize and bind DNA
What are Cas genes?
Genes encoding proteins (nucleases like Cas9) that perform CRISPR functions
What are crRNAs?
CRISPR RNAs derived from the CRISPR array that guide Cas nucleases to target DNA
What organism is the Cas9 system derived from?
Streptococcus pyogenes
What RNAs are needed for CRISPR-Cas9?
crRNA and tracrRNA
How does Cas9 target DNA?
The sgRNA base-pairs with the target DNA next to a PAM site, and Cas9 makes a double-strand break
What are the two major DNA repair pathways used after Cas9 cleavage?
NHEJ (Non-Homologous End Joining), HDR (Homology-Directed Repair)
What is NHEJ?
Non-Homologous End Joining: Error-prone, creates indels
What is HDR?
Homology-Directed Repair: Accurate, uses a donor DNA template
What determines the editing outcome in CRISPR?
The repair pathway and whether a donor template is supplied
What types of edits can CRISPR perform?
Point mutations, Insertions, Deletions, Replacements, Inversions, Translocations
What are base editors?
CRISPR variants that install precise point mutations without cutting DNA
What are prime editors?
Cas9 nickase + reverse transcriptase; enables precise insertions, deletions, and all base conversions
What are two general delivery strategies for CRISPR?
Ex vivo, In vivo
What are some delivery vectors used for CRISPR?
Viral (e.g., AAV), Nanoparticles, Electroporation, Lipid-based transfection
What diseases are being targeted by CRISPR in clinical trials?
Sickle cell disease, β-thalassemia, Cancer, Retinal diseases (e.g., Leber congenital amaurosis)
