Milestones in Biology 3 Test Your Knowledge

What was the typical sequence length that could be obtained in a single read at the time the HGP began?
a. ~25 nucleotides

b. ~50 nucleotides

c. ~100 nucleotides

d. ~500 nucleotides

e. ~1,500 nucleotides

d

Why were computational advances particularly important for the success of the Venter–Celera approach to sequencing the human genome?

Because the Venter-Celera approach required piecing together (in the right order) massive numbers of genome fragments. An enormous amount of data had to be processed, requiring the development of new programs and algorithms.

Both Collins and the NIH team and Venter and the Celera team relied on shotgun sequencing at some point. What differed between the approaches of the two teams?

Shotgun sequencing is the breaking up the genome into random small fragments, then sequencing these shorter fragments and putting the sequences back together. The NIH team used a hierarchical approach: they first fragmented individual chromosomes into large pieces, mapped the pieces onto their physical location on the chromosome, then carried out shotgun sequencing on these larger pieces. The Celera team “shotgunned” the entire genome, without first mapping any sections of DNA onto a physical location. They then assembled the entire genome sequence from the small shotgun fragments.

What were some surprises in the human genome?
a. The number of nucleotides was much smaller than expected.

b. The number of genes was much smaller than expected.

c. A small new chromosome was discovered.

d. The sequence is extremely similar between different people.

e. all of the above

b

The National Center for Genome Resources has developed a test that allows couples to determine whether they are carriers for mutations in genes that can cause devastating and lethal genetic diseases in their children. Would you want to take this test before having a child? What do you think you would do if you and your partner were found to be at risk for having a child with a lethal genetic disease?

Answers will vary.