Question 1

Which of the following best describes the role of Cas9 in CRISPR genome editing?

Accepted Answer

Cas9 is an enzyme that makes double-stranded cuts in DNA at locations specified by a guide RNA.

Question 2

What is the main advantage of using CRISPR-Cas9 over older genetic engineering techniques?

Accepted Answer

CRISPR-Cas9 allows for faster, easier, cheaper, and more accessible gene editing.

Question 3

A scientist wants to correct a single base pair mutation in a human gene using CRISPR-Cas9. Which DNA repair pathway must be activated to ensure precise correction?

Accepted Answer

Homology-directed repair (HDR)

Question 4

Why does Cas9 require a guide RNA to target specific DNA sequences?

Accepted Answer

Guide RNA base pairs with the target DNA sequence, directing Cas9 to the correct location.

Question 5

If a mutation caused by CRISPR-Cas9 results in a frameshift, what is the most likely consequence for the protein encoded by that gene?

Accepted Answer

The protein will be severely impaired or nonfunctional due to altered amino acid sequence.

Question 6

Which of the following equations best represents the probability of a specific 6-base sequence occurring in random DNA, assuming equal base distribution?

Accepted Answer

$$P = \frac{1}{4^6$}$$

Question 7

What is a major ethical concern associated with germline editing using CRISPR-Cas9?

Accepted Answer

Germline editing can result in permanent changes passed on to future generations.

Question 8

In most eukaryotic cells, which DNA repair mechanism is most commonly used after a double-stranded break induced by Cas9?

Accepted Answer

Non-homologous end joining (NHEJ)

Question 9

A researcher uses a mutated Cas9 that can bind DNA but cannot cut it. What is a potential application of this 'dead' Cas9?

Accepted Answer

Labeling specific DNA sequences or activating gene expression.

Question 10

Which of the following best explains why CRISPR-Cas9 is considered a revolutionary tool in medicine?

Accepted Answer

It enables targeted correction of genetic disorders, potentially curing previously untreatable diseases.

Question 11

What is the function of the PAM (Protospacer Adjacent Motif) sequence in CRISPR-Cas9 genome editing?

Accepted Answer

It is a short DNA sequence that Cas9 must recognize to bind and cut the target DNA.

Question 12

A scientist wants to insert a new gene into a cell using CRISPR-Cas9. Which step is essential for ensuring the new gene is incorporated?

Accepted Answer

Providing a DNA template with homology to the target site for HDR.

Question 13

Which of the following is NOT a potential application of CRISPR-Cas9 technology?

Accepted Answer

Synthesizing ATP directly from DNA.

Question 14

If a scientist wants to use CRISPR-Cas9 to create a knockout mutation in a gene, which DNA repair pathway is most likely to result in a loss-of-function mutation?

Accepted Answer

Non-homologous end joining (NHEJ)

Question 15

Which of the following statements about guide RNA in CRISPR-Cas9 is correct?

Accepted Answer

Guide RNA is a short RNA molecule that directs Cas9 to a specific DNA sequence by base pairing.

Question 16

Which equation represents the number of possible 20-nucleotide guide RNA sequences, assuming four possible bases at each position?

Accepted Answer

$$N = 4$$^{20}$$

Question 17

Why do scientists often use a simplified guide RNA design in laboratory CRISPR experiments?

Accepted Answer

To make the guide RNA more stable and easier to synthesize.

Question 18

Which of the following best describes the difference between somatic and germline genome editing?

Accepted Answer

Somatic editing affects only the individual, while germline editing can be inherited by future generations.

Question 19

A patient with sickle cell disease is treated using CRISPR-Cas9 to correct the mutation in their blood stem cells. What is the most likely outcome?

Accepted Answer

The patient’s blood cells will function normally, but the change will not be passed to offspring.

Genome Editing with CRISPR-Cas9: Principles, Applications, and Ethical Considerations

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