For each question, choose the ONE BEST answer or completion.
1. When a DNA strand with the sequence 3' GACTAACGATGC 5' is used as a template on which a daughter DNA sequence is formed, the daughter strand has the sequence
A. 3' CTGATTGCTACG 5'
B. 5' GCATCGTTAGTC 3'
C. 5' CTGATTGCTACG 3'
D. 3' CGTAGCAATCAG 5'
E. 3' CGUAGCAAUCAG 5'
2. Okazaki fragments are
A. short peptide sequences.
B. RNA primers.
C. newly synthesized stretches of DNA produced during replication of the lagging template strand.
D. degraded fragments of DNA.
E. the lengths of DNA between origins of replication.
3. Following a spontaneous DNA deamination of cytosine that generates uracil, repair proceeds in the following order:
A. Removal of the uracil from its ribose, removal of the sugar to leave a gap, addition of an appropriate new deoxyribonucleotide, reformation of the phosphodiester links.
B. Removal of the sugar from the sugar-phosphate backbone, removal of the hydrogen-bonded uracil, addition of an appropriate new deoxyribonucleotide, reformation of the phosphodiester links.
C. Removal of the uracil from its ribose, insertion of cytosine which hydrogen bonds to guanosine, reformation of the bond between cytosine and ribose.
D. Addition of an appropriate new deoxyribonucleotide to the opposite side of the DNA helix, rotation of the helix by topisomerase 1, reformation of the phosphodiester links.
E. Transamination of uracil to regenerate cytosine, checking of the conversion by self-correcting DNA polymerase.
4. Which of the following do not play a role in replication?
A. RNA primers
D. Stop codons
E. DNA polymerase
5. During DNA replication, the new DNA is formed on the lagging strand in a series of independent short sections because
A. DNA polymerase III can synthesize DNA in both the 3' to 5' and 5' to 3' directions but makes more mistakes when working in the 5' to 3' direction.
B. DNA polymerase III can only operate in the 5' to 3' direction.
C. Thymine dimers are excised from the growing strand, leaving it cut into short fragments.
D. The hydrogen bonding between adenine and thymine is relatively weak.
E. DnaA causes the DNA strands to melt.
6. The human genome comprises
A. protein-coding genes.
B. genes encoding mRNAs.
C. sequences that do not encode genes.
D. genes for ribosomal RNAs and transfer RNAs.
E. all of the above.
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