1. (a) What is the structural differencebetween all deoxyribonucleotides and all ribonucleotides and whydoes this make DNA more appropriate to act as the genetic materialthan RNA. (4 points)
(b) Why is uracil replaced by thymine in DNA? (4 points)
(c) Can ribonucleotides base-pair with a deoxyriboncleotides andif so when does this happen? (4 points)
(d) The two strands in DNA are antiparallel. What does thismean? (4 points)
(e) Why are they antiparallel? (4 points)
2. A single stranded DNA molecule has thefollowing sequence: 5'-GGTTAGGTTAGGTTAGGTTA-3'
(a) To fully replicate this molecule, what is the sequence ofthe primer that must be synthesized by the primase enzyme (assume aprimer length of 5 bp). (Here and below write how you wouldconventionally write a single stranded DNA sequence, i.e. withoutthe template.) (4 points)
(b) When fully replicated, what is the sequence of the newlysynthesized DNA strand? (4 points)
(c) What is the sequence of the molecule synthesized in theabsence of DNA pol I? (4 points)
(d) What is the sequence of what would be synthesized in theabsence of DNA ligase? (4 points)
(e) What is the total number of H-bonds that are formed duringthe synthesis of the DNA strand (from the very beginning)? (4points)
3. Different temperature sensitive mutants ofE. coli in genes encoding proteins involved in replication weregrown at the permissive temperature for several generations andwhile still actively growing the temperature was raised to therestrictive temperature. After raising temperature, the synthesisof new DNA was assessed using radioactively labeled nucleotides.Assume the mutations completely inactivate the proteins at therestrictive temperature and that function of the mutant protein wasabolished instantly temperature was raised. Would any new DNA bedetected in the following mutants after raising thetemperature?
(4 points each) (a) DnaA
(b) DNA helicase
(c) DNA primase
(d) DNA pol I
(e) DNA pol III
