5. Dideoxynucleosides are employed in the course of the Sanger process of DNA sequencing. Dideocynucleosides are used because

Question

a) They stop the synthesis of DNA strands
b) They are fluoresce
c) They are radioactive
d) They move quicly during gel electrophoresis
e) They stabilize small double-standed DNA fragments
MY ANSWER: a
6. Gel Electrophoresis sperates fragments of DNA using
a) a sieving medium through which DNA fragments are moved by gravitational forces
b) repulsion of charged DNA molecules by the electrically charged gel beads
c) a sieving medium through which DNA molecules are moved by electrical forces
d) movement through a sieving medium by positively charged DNA molecules attracted by ultracentrifugation
MY ANSWER: c
7. A fragment of DNA is called recombinant if
a) when separated by heat, it will anneal on cooling
b) it is acted upon by spliceosomes and parts of it are existed
c) it has been amplified using the polymerase chain reaction
d) it has been reverse transcribed from RNA
e)it contains DNA sequences from more than one source

8. The recognition sites of fie restriction endonucleases are shown below. Which would make cuts in the following DNA fragment? You will need to draw in the complementary DNA strand before attempting this question.
5’-GCAAGCTTGCTGCAGAATTACCCGGA-3’
Recognition Sites:
EcoRI 5’-GAATTC-3’
3’-CTTAAG-5’
SmaI 5’-GGGCCC-3’
3’-CCCGGG-5’
AluI 5’-AGCT-3’
3’-TCGA-5’
HindIII 5’-AAGCTT-3’
3’-TTCGAA-5’
a) HindIII and Smal
b) EcoRI and AluI
c) EcoRI and SalI
d) EcoRI and HindIII
e) AluI and HindIII
MY ANSWER : b