Question 1

Which of the following best describes the function of restriction enzymes in bacterial innate immunity?

Accepted Answer

They cleave specific DNA sequences in invading bacteriophage DNA.

Question 2

In the CRISPR-Cas system, what is the primary role of the spacer sequences found between palindromic repeats?

Accepted Answer

They are sequences from invading viruses or plasmids, serving as molecular memory.

Question 3

Which of the following is required for Cas9 to cleave a target DNA sequence during genome editing?

Accepted Answer

Presence of a PAM sequence adjacent to the target site.

Question 4

A researcher wants to induce random insertions and deletions (indels) in a gene using CRISPR-Cas9. Which repair pathway should be utilized?

Accepted Answer

Nonhomologous end-joining (NHEJ) to ligate fragments.

Question 5

Which equation correctly represents monosomy in a diploid organism?

Accepted Answer

$$2n - 1$$

Question 6

Familial Down syndrome is most commonly caused by which chromosomal event?

Accepted Answer

Robertsonian translocation between chromosomes 14 and 21.

Question 7

Which of the following statements about inversions is correct?

Accepted Answer

Balanced inversions generally do not affect phenotype unless breakpoints disrupt genes or regulatory regions.

Question 8

Aneuploidy can be produced through nondisjunction in which of the following cellular processes?

Accepted Answer

Meiosis I, meiosis II, or mitosis.

Question 9

Which chromosomal rearrangement is most likely to cause a position effect phenotype?

Accepted Answer

Translocation

Question 10

Which of the following best explains why bacteria do not destroy their own CRISPR spacer DNA during Cas9-mediated cleavage?

Accepted Answer

Cas9 only cleaves DNA adjacent to a PAM sequence, which is absent in the bacterial CRISPR locus.

Question 11

Which of the following is NOT a way that deletions can cause abnormal phenotypes?

Accepted Answer

Haploinsufficient genes can result because too much gene product is produced.

Question 12

Which repair pathway is less error-prone and can be used for precise genome editing with CRISPR-Cas9?

Accepted Answer

Homology-directed repair (HDR) using an artificial donor template

Question 13

Which of the following is a special case of nonreciprocal translocation involving fusion of two acrocentric chromosomes?

Accepted Answer

Robertsonian translocation

Question 14

Which of the following statements about duplications is correct?

Accepted Answer

Duplicated regions increase gene dosage, which affects processes like development that require specific amounts of protein.

Question 15

Which of the following best describes the difference between innate and adaptive immunity in bacteria?

Accepted Answer

Innate immunity is immediate and non-specific, while adaptive immunity is delayed, highly specific, and forms memory.

Question 16

Which of the following chromosomal mutations does NOT alter the structure of chromosomes?

Accepted Answer

Aneuploidy

Question 17

Which equation correctly represents nullisomy in a diploid organism?

Accepted Answer

$$2n - 2$$

Question 18

Which of the following is a real-world example of a disease caused by chromosomal translocation?

Accepted Answer

Chronic myelogenous leukemia (CML)

Question 19

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

Accepted Answer

Cas nucleases cleave viral DNA and insert fragments into CRISPR loci as new spacers.

Genetic Mapping, CRISPR-Cas Systems, and Chromosome Mutations: Advanced Genetics Study Notes

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