Question

Which of the following is incorrect?

(a) Initial DNA sequencing reactions generate short sequence reads from DNA clones

(b) To assemble a whole genome sequence, these short fragments are joined to form larger fragments

(c) The average length of the reads is about 50 bases

(d) A number of overlapping contigs can be further merged to form scaffolds

I got this question in examination.

Question is taken from Genome Sequence Assembly topic in division Genome Mapping, Assembly and Comparison of Bioinformatics

Answer 1

Correct answer is (c) The average length of the reads is about 50 bases

The best I can explain: The average length of the reads is about 500 bases. To assemble a whole genome sequence, these short fragments are joined to form larger fragments after removing overlaps. These longer, merged sequences are termed contigs, which are usually 5,000 to 10,000 bases long. A number of overlapping contigs can be further merged to form scaffolds (30,000–50,000 bases, also called supercontigs), which are unidirectionally oriented along a physical map of a chromosome.