Question 1

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

Accepted Answer

It acts as a prokaryotic adaptive immune system by storing viral DNA sequences and targeting them for destruction.

Question 2

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

Accepted Answer

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

Question 3

Which component of the CRISPR-Cas system is responsible for recognizing and cutting the target DNA?

Accepted Answer

Cas9 protein

Question 4

A scientist wants to use CRISPR-Cas9 to insert a new gene into a plant genome. Which DNA repair pathway is most desirable for precise insertion?

Accepted Answer

Homology-directed repair (HDR)

Question 5

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

Accepted Answer

It directs Cas9 to the specific DNA sequence to be cut by base pairing with the target.

Question 6

Which of the following is a major ethical concern associated with human germline genome editing using CRISPR-Cas technology?

Accepted Answer

Potential for edits to be passed on to future generations without consent.

Question 7

Why is the CRISPR-Cas9 system considered 'programmable'?

Accepted Answer

Because the guide RNA sequence can be designed to target any DNA sequence of interest.

Question 8

Which of the following agricultural applications has been achieved using CRISPR-Cas technology?

Accepted Answer

Engineering crops to be more resistant to drought.

Question 9

A researcher designs a sgRNA to target a gene in a mammalian cell. The target DNA sequence is 5'-AGCGTTA-3'. Which sgRNA sequence should be used?

Accepted Answer

$$5'\ UAACGCU\ 3'$$

Question 10

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

Accepted Answer

Cas1

Question 11

What is the main reason why CRISPR-Cas9 does not target and cut the host bacterial genome?

Accepted Answer

The host genome lacks the PAM sequence adjacent to the target site.

Question 12

Which of the following is NOT a potential use of CRISPR-Cas technology?

Accepted Answer

Synthesizing proteins required for photosynthesis.

Question 13

A patient with sickle cell disease receives a CRISPR-based therapy. What is the most likely approach used?

Accepted Answer

Ex vivo editing of stem cells followed by reintroduction into the patient.

Question 14

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

Accepted Answer

dCas9 can be fused to other proteins for transcriptional control or imaging.

Question 15

Which equation best represents the relationship between the number of possible CRISPR repeat units ($$k) $$and the length of each repeat ($$d) if $$each nucleotide can be one of four bases?

Accepted Answer

$$k = 4^d$$

Question 16

Which of the following is a reason why CRISPR-edited plants are sometimes not considered GMOs in the US?

Accepted Answer

The edits can be a single base pair change that could occur naturally.

Question 17

Which step is essential for CRISPR-Cas9 to successfully edit a genome in a laboratory setting?

Accepted Answer

Designing a sgRNA complementary to the target DNA sequence.

Question 18

Which of the following is a plausible consequence of off-target effects in CRISPR-Cas9 genome editing?

Accepted Answer

Unintended mutations in non-target genes leading to potential health risks.

Question 19

Which of the following best explains why CRISPR-Cas9 technology has revolutionized genetic research in model organisms like C. elegans?

Accepted Answer

It allows for precise, targeted genome editing with minimal off-target effects.

Question 20

Which of the following is NOT a necessary component for a CRISPR-Cas9 reaction?

Accepted Answer

DNA polymerase

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

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