Question 1

Which of the following best describes the natural function of the CRISPR-Cas system in prokaryotes?

Accepted Answer

It provides adaptive immunity by storing viral DNA sequences and targeting them during future infections.

Question 2

What is the role of the protospacer adjacent motif (PAM) in CRISPR-Cas9 genome editing?

Accepted Answer

It is required for Cas9 to recognize and cut the target DNA sequence.

Question 3

A researcher wants to use CRISPR-Cas9 to introduce a specific mutation into a gene in mouse cells. Which repair pathway must be activated to ensure precise insertion of the desired DNA sequence?

Accepted Answer

Homology-directed repair (HDR)

Question 4

Which of the following is NOT a typical application of CRISPR-Cas technology in agriculture?

Accepted Answer

Introducing entirely new metabolic pathways from animals into plants

Question 5

In the CRISPR-Cas9 system, what is the function of the single guide RNA (sgRNA)?

Accepted Answer

It provides the sequence specificity for Cas9 to bind and cut the target DNA.

Question 6

Why is human germline genome editing considered unethical by the international scientific community at this time?

Accepted Answer

Because changes made to germline cells are heritable and could affect future generations.

Question 7

Which of the following best explains why the CRISPR-Cas9 system does not target the bacterial genome itself?

Accepted Answer

The bacterial genome lacks the protospacer adjacent motif (PAM) required for Cas9 activity.

Question 8

A scientist wants to use CRISPR-Cas9 to knock out a gene in Drosophila. Which of the following steps is essential for ensuring that only the target gene is disrupted?

Accepted Answer

Designing a sgRNA that is complementary to a unique sequence in the target gene and adjacent to a PAM site.

Question 9

Which Cas protein is primarily responsible for integrating new viral DNA sequences into the CRISPR array during adaptation?

Accepted Answer

Cas1

Question 10

A patient with sickle cell disease is treated with a CRISPR-based therapy. Which approach is most likely used in this case?

Accepted Answer

Ex vivo editing of hematopoietic stem cells followed by transplantation

Question 11

Which of the following statements about dCas9 (deactivated Cas9) is correct?

Accepted Answer

dCas9 can be fused to other proteins to localize them to specific genomic regions.

Question 12

Which of the following is a key advantage of CRISPR-Cas9 genome editing compared to earlier methods such as using UV or gamma radiation?

Accepted Answer

CRISPR-Cas9 allows for targeted and precise genome modifications.

Question 13

A CRISPR array in a bacterium contains several spacers. What do these spacers represent?

Accepted Answer

Short sequences derived from previous viral infections.

Question 14

Which of the following equations correctly represents the requirement for a PAM site in CRISPR-Cas9 targeting?

Accepted Answer

$$	ext{Target DNA} = 	ext{sgRNA match} + 	ext{PAM (NGG)}$$

Question 15

Which of the following is a potential ethical concern associated with CRISPR-Cas genome editing?

Accepted Answer

Heritable changes resulting from germline editing

Question 16

A scientist is designing a sgRNA to target the DNA sequence 5'-AAGTGATATCCAT-3'. Which of the following is the correct sgRNA sequence (written 5' to 3') to pair with this target, assuming the PAM is present on the target DNA?

Accepted Answer

Question 17

Which of the following best describes the process of adaptation in the CRISPR-Cas system?

Accepted Answer

The integration of new viral DNA sequences into the CRISPR array after infection.

Question 18

Which of the following is a real-world example of a CRISPR-edited crop that has been commercially released?

Accepted Answer

Tomatoes enriched for GABA

Question 19

Which of the following statements about the Nobel Prize in Chemistry awarded to Emmanuelle Charpentier and Jennifer Doudna is correct?

Accepted Answer

They were recognized for developing CRISPR-Cas9 as a genome editing tool.

CRISPR-Cas Systems and Genome Editing: Mechanisms, Applications, and Implications

Study Guide - Practice Questions

Study Guide - Flashcards