Lecture 34 Self Assessment DNA Structure II Chromatin Topology Replication Lecture 35 1 Euchromatin Heterochromatin readily decondenses for transcription 2 Euchromatin Heterochromatin is found constitutively in this state at the telomere and centromere of prokaryotic eukaryotic 4chromosomes 3 Portions of the chromatin which can condense or decondense as needed is facultative heterochromatin constitutive4heterochromatin 4 If a piece of DNA has 1040 bp and Writhe 0 what is the twist 100 5 What is the linking number 100 6 Change in DNA linking number can only happen when the DNA is cut TF 7 DNA molecules that differ in linking number are alleles topoisomers analogs 4 8 Name the two main differences between Topoismerase I and II Topoisomerase I makes one cut in the DNA and the linking number changes by one another is that this process does not require ATP but just the release of tension to power this change in linking number Topoisomerase II requires ATP cuts both strands and changes the linking number by 2 9 Replication requires a primer b DNA template NTPs and dNTPs c Mg2 10 What is the function of Mg2 in replication also has the same role in transcription it turns out Helps to position the phosphate groups for optimal reaction distance and catalyzes the reaction 11 What feature of DNA polymerase ensures that the correct bases are added and that the incorrect bases are excised by the endonuclease function of DNA polymerase Hydrogen bonding between the bases in the minor groove of DNA and the amino acids in the polymerase Arginine and Glutamine do not occur unless the correct deoxynucleotide has been added an incorrect pair would not allow the nucleotide to be held tightly and this nucleotide would slip into the exonuclease and be cleaved off 12 The DNA helicase that functions in eukaryotic replication is Mcm2F7 13 The DNA Polymerase that replicates the leading strand in eukaryotes is DNA Polymerase epsilon 14 This enzyme clears DNA RNA heteroduplexes in eukaryotes RNAseH while in prokaryotes it is DNA POLI 15 Enzyme that seals the nick left by excision of primers in both eukaryotes and prokaryotes called DNA Ligase 16 DNA TEMPLATE is read in the 3 to 5 direction 17 RNA PRIMERS are polymerized in the 5 to 3 direction Lecture 34 Self Assessment DNA Structure II Chromatin Topology Replication 18 DNA POL III is a polymerase in prokaryotes eukaryotes 4that4serves this purpose Main replicative DNA polymerase 19 Initiation occurs at one origin of replication per genome in both prokaryotes and eukaryotes True False Please make sure to study replication initiation in both prokaryotes and eukaryotes Know the proteins and enzyme that work to allow DNA polymerase to begin replication
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