Homework Problems for Review Session 10 9 25 DNA synthesis Which of the following is true about DNA 1 DNA polymerase forms phosphodiester bonds by connecting the 3 OH of the new nucleotide to the 5 triphosphate of the previous nucleotide 2 G C base pairs have stronger hydrogen bonding than A T base pairs 3 The nitrogenous bases are attached to the 1 carbon on the deoxyribose sugar 4 The DNA double helix is relatively sti and does not bend easily 5 Chromatin contains both DNA and histone proteins 6 One of the two sister chromatids is made of short pieces called Okazaki fragments 7 The other sister chromatid is made of one continuous double stranded DNA molecule 8 There are always more purines in DNA than pyrimidines 9 New nucleotides added during DNA synthesis are nucleotide triphosphates or dNTPs 10 Single stranded DNA molecules will anneal if they have identical sequences and the temperature is low enough 11 Nitrogenous bases of DNA are of two types purines and pyrimidines 12 A and T are purines and G and C are pyrimidines You analyze a segment of DNA and nd the following part of the segment is double stranded part of the segment has single stranded regions RNA primers are present What else could be true about this DNA segment or the cell it is in 1 The segment contains an origin of replication 2 DNA Helicase is active in this region 3 Addition of new deoxy nucleotides into a DNA strand is occurring 4 DNA ligase function is completed 5 DNA polymerase III is active 6 Rb is partially phosphorylated 7 DP1 is fully phosphorylated Match the following with the stage of cell cycle they occur in A G1 B S C G2 D M 1 Rb is unphosphorylated 2 Helicase is being expressed 3 DP1 is phosphorylated 4 RNA primers are being removed from DNA 5 Cyclin B levels are high 6 Cyclin E is undergoing ubiquitin dependent proteolysis 7 Okazaki fragments are present 8 Proteins are holding double stranded DNA molecules together Ori 3 5 If a replication bubble were to open at the Origin of replication shown which of the following would be true 1 Two replication forks would form one to the left of the Ori and one to the right 2 The top strand would be the template for the leading strand of the left replication fork 3 The top strand would be the template for the leading strand of the right replication fork 4 The bottom strand would be the template for the lagging strand of the left replication fork 5 The bottom strand would be the template for the leading strand of the right replication fork HW Which of the following would function more on the lagging strand than the leading strand 1 Primase 2 DNA Polymerase III 3 DNA Polymerase I 4 single strand binding protein 5 DNA Ligase HW DNA func on Analysis of a cell shows the following DP1 is phosphorylated Expression of the gene encoding DNA ligase has ended DNA Helicase has completed its RNA primers are present in the p53 is ac vated What else could be true 1 Rb should be fully phosphorylated 2 DNA polymerase III has already func oned 3 DNA polymerase I is defec ve 4 Topoisomerase has already func oned 5 CDKI levels are low 6 DNA ligase has completed its func on 7 The cell are in G2 phase Analysis of a single cell shows the following MEK is phosphorylated cAMP levels are low CDK4 6 is ac vated Cyclin A levels are low but rising SR ac vates Cyclin D EGF ac vates Cyclin E Adrenaline blocks EGF If this was a normal healthy cell what else would be true about this cell 8 The EGF receptor would be dimerized 9 G protein alpha would be binding GDP 10 Rb would be fully phosphorylated 11 DP1 would be phosphorylated 12 Okazaki fragments would be present 13 The cell would be in G2 phase 14 RNA primase would be ac ve 15 DNA Helicase would be inac ve 16 APC would be binding to CDC20