Question on DNA sequancing

DNA sequancing

1. Which of the following is untrue about DNA sequencing methods?

a) Purified fragments of DNA cut from plasmid/phage clones or amplified by polymerase chain reaction (PCR)
b) Clones of DNA fragments are denatured to single strands, and one of the strands is hybridized to an oligonucleotide primer
c) Taq polymerase is quite heat sensitive
d) New strands of DNA are synthesized from the end of the primer

Answer: c

2. Using ddATP, the resulting synthesis creates a set of nested DNA fragments, each one ending at one of the as in the sequence through the substitution of a fluorescent-labeled ddATP.
a) True
b) False

Answer: a

3. The combined mixture of all labeled DNA fragments is electrophoresed to _____ the fragments by______ and the ladder of fragments is scanned for the presence of each of the four labels.
a) separate, size
b) separate, pH
c) assimilate, pH
d) assimilate, size

Answer: a

4. The sequence can also be verified by making an oligonucleotide primer complementary to the distal part of the readable sequence and using it to obtain the sequence of the complementary strand on the original DNA template.
a) True
b) False

Answer: a

5. When the process is fully automated, a number of priming sites may be used to obtain sequencing results that give optimal separation of bands in each region of the sequence.
a) True
b) False

Answer: a

6. To sequence larger molecules, individual chromosomes are purified and broken into _____ or larger random fragments, which are cloned into vectors designed for large molecules.
a) 100-Mb
b) 100-kb
c) 5000-kb
d) 600-kb

Answer: b

7. Many levels of clone redundancy may be required to build a consensus map because individual clones can have _______
a) rearrangements
b) deletions
c) two separate fragments
d) vectors

Answer: d

8. Once the correct map has been obtained, unique overlapping clones are chosen for sequencing.
a) True
b) False

Answer: a

9. An alternative method is to sequence all the subclones, produce a computer database of the sequences, and then have the computer assemble the sequences from the overlaps that are found.
a) True
b) False

Answer: a

10. Which of the following is untrue about Shotgun Sequencing?
a) When DNA fragments derived from different chromosomal regions have repeats of the same sequence, they will appear to overlap
b) When DNA fragments derived from different chromosomal regions have repeats of the same sequence, they will appear to scrutinize
c) In a new whole shotgun approach, Celera Genomics is sequencing both ends of DNA fragments of short (2 kb), medium (10 kb), and long (BAC or >100 kb) lengths
d) A large number of reads are then assembled by computer

Answer: b