661. Nucleoside is a pyrimidine or purine base
A. covalently bonded to a sugar
B. ionically bonded to a sugar
C. hydrogen bonded to a sugar
D. none of the above

662. In gel electrophoresis, what fragments will move most quickly through a gel?
A. Large fragments
B. Small fragments
C. Large genome
D. None of these

663. Which pyrimidine base contains an amino group at carbon 4?
A. Cytosine
C. Uracil
D. Adenine

664. Nucleotide bases and aromatic amino acids absorb light respectively at
A. 280 and 260 nm
B. 260 and 280 nm
C. 270 and 280 nm
D. 260 and 270 nm

665. The glycosidic bonds in DNA and RNA
A. connect the sugar to the base
B. can be hydrolyzed by OH- ion
C. stabilize Watson-Crick H-bonds
D. are free to rotate over about 180°

666. Nucleic acids can be analyzed experimentally by their
A. molecular weight
B. absorption of visible light
C. absorption of uv light
D. none of these

667. Thymidine
A. can participate in hydrophobic interactions due to its methyl group
B. is replaced by uracil in RNA
C. normally forms two hydrogen bonds with adenosine
D. all of the above

668. A nucleotide consists of
A. a sugar, a base and a phosphate
B. a sugar and a phosphate
C. paired bases
D. a sugar, a base and three phosphates

669. A five carbon sugar lacking a hydrogen at the number 2 carbon is found in

670. The unfavourable free energy associated with not satisfying a hydrogen bond after formation of the double helix is approximately
A. 10 kJ/mol
B. 20 kJ/mol
C. 25 kJ/mol
D. 30 kJ/mol