Question 1

Which of the following best describes a Robertsonian translocation?

Accepted Answer

A fusion of the long arms of two acrocentric chromosomes, resulting in a single chromosome.

Question 2

In Sanger sequencing, what is the role of dideoxynucleotide triphosphates (ddNTPs)?

Accepted Answer

They terminate DNA synthesis by preventing addition of further nucleotides.

Question 3

Which DNA sequencing technology is most suitable for accurately sequencing through highly repetitive regions of the genome?

Accepted Answer

Third generation sequencing

Question 4

What is the main advantage of next generation sequencing (NGS) over Sanger sequencing?

Accepted Answer

NGS can sequence many DNA fragments in parallel, increasing throughput.

Question 5

During DNA synthesis, which direction does DNA polymerase add nucleotides to the growing strand?

Accepted Answer

$5' \rightarrow 3'$

Question 6

Which of the following is a key feature of third generation sequencing technologies?

Accepted Answer

They produce long reads, allowing for assembly of entire genomes and detection of large-scale variants.

Question 7

In the DNA synthesis reaction, what is released as a byproduct when a nucleotide is added to the growing DNA strand?

Accepted Answer

A pyrophosphate group ($PP_i$)

Question 8

Which sequencing method relies on reversible chain termination chemistry?

Accepted Answer

Next generation sequencing (Illumina)

Question 9

A researcher wants to identify the precise breakpoints of a Robertsonian translocation in a patient’s genome. Which sequencing technology would be most effective for this purpose?

Accepted Answer

Third generation sequencing

Question 10

Why do next generation sequencing (NGS) reads need to be computationally aligned?

Accepted Answer

Because NGS produces short reads that must be overlapped to reconstruct the original sequence.

Question 11

Which of the following statements about Sanger sequencing is TRUE?

Accepted Answer

It generates one sequence at a time and is considered slow but accurate.

Question 12

What is the function of a primer in a DNA synthesis reaction?

Accepted Answer

It initiates DNA synthesis by providing a free $3'$-OH group for nucleotide addition.

Question 13

Which of the following is a disadvantage of third generation sequencing compared to NGS?

Accepted Answer

It is more expensive per reaction.

Question 14

A patient’s genome contains a repetitive DNA region that is difficult to sequence using NGS. Which sequencing technology would best overcome this challenge?

Accepted Answer

Third generation sequencing

Question 15

Which of the following is NOT a component required for a Sanger sequencing reaction?

Accepted Answer

RNA polymerase

Question 16

In next generation sequencing (NGS), what is the purpose of ligating adaptors to DNA fragments?

Accepted Answer

To allow fragments to bind to the flow cell and serve as primer binding sites.

Question 17

Which of the following best explains why third generation sequencing is useful for identifying quasispecies in viral genomes?

Accepted Answer

It can sequence an entire genome in one read, allowing identification of multiple variants within a single host.

Question 18

Which of the following statements about DNA polymerase is correct?

Accepted Answer

It adds nucleotides to the $3'$ end of a primed, single-stranded template.

Question 19

A researcher is sequencing a genome with many large chromosomal deletions and inversions. Which sequencing technology would be most appropriate?

Accepted Answer

Third generation sequencing

Question 20

Which of the following is a limitation of short-read sequencing technologies?

Accepted Answer

They may miss large structural variants due to gaps in sequence assembly.

DNA Sequencing Technologies and Chromosomal Rearrangements: Study Notes for Genetics

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