Whole-genome sequencing (WGS) determines the order of DNA bases across an organism’s entire genome. This lesson introduces why sequencing can help investigate disease and explains the main methods scientists use to read and assemble DNA sequences.
Doctors may use sequencing when a disease has a suspected genetic basis but its cause is not clear. WGS examines the entire genome, providing a broad search for genetic variants that may help explain a condition. It is a powerful, relatively broad approach, but identifying a sequence difference does not automatically prove that it causes a disease; results need careful interpretation.
All flashcards
What is whole-genome sequencing?
A process that determines the DNA sequence across an entire genome. It can help researchers investigate genetic causes of disease and other biological questions.
How does whole-exome sequencing differ from WGS?
Whole-exome sequencing focuses on exon-containing, protein-coding regions, whereas WGS examines the entire genome, including noncoding regions.
What is the role of a ddNTP in Sanger sequencing?
A ddNTP is a fluorescently labeled DNA building block that stops strand extension when incorporated because it lacks the group needed to add another nucleotide.
What is a contig?
A longer DNA sequence assembled from overlapping shorter sequences or fragments.
What does sequence alignment reveal?
It arranges DNA, RNA, or protein sequences so that similar and different regions can be compared. Similarities may provide clues about shared function, structure, or evolutionary relationships.
Quiz questions
Which regions are the primary target of whole-exome sequencing?Answer: Exon-containing regions that code for proteins.
Why does a ddNTP terminate DNA strand extension during Sanger sequencing?Answer: It lacks the hydroxyl group needed to attach the next nucleotide.
How can sequencing both ends of a DNA fragment aid assembly?Answer: The two end sequences provide additional clues about the fragment's placement.
What can be concluded when whole-genome sequencing finds a DNA difference in a patient?Answer: The difference may warrant investigation but does not by itself prove disease causation.
How do DNA microarrays differ from whole-genome sequencing?Answer: Microarrays test selected targets represented on the array, while sequencing can survey genome-wide sequence information.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.