BIOL 1107 1nd Edition Lecture 11 Outline of Last Lecture I Interphase a G1 Phase b S Phase c G2 Phase II Mitosis a Prophase b Prometaphase c Metaphase d Anaphase e Telaphase III Cytokinesis IV Mitosis vs Meiosis V Meiosis VI Meiosis Outline of Current Lecture I DNA Synthesis Current Lecture I DNA Synthesis Most prokaryotes have circular single chromosomes while they are linear in eukaryotes Replication proceeds in both directions form 5 to 3 end because DNA has directionality you can only add a nucleotide to a previous nucleotide to 3 end Living things have regions where an enzyme moves in and breaks hydrogen bonds Several proteins are responsible for opening and stabilizing the double helix o The enzyme helicase is responsible for this catalyzes the breaking of hydrogen bonds between the two DNA strands to separate them o Then single strand DNA binding proteins SSBPs attach to the separated strands to prevent them from re bonding and closing reuniting o Another enzyme cuts strand to get rid of the tension then rejoins them These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute DNA polymerase requires a primer indicated process of replication o Provides free 3 hydroxyl OH group that can combine with something to form a phosphodiester bond Primase a type of RNA polymerase synthesizes an RNA primer to synthesis a DNA strand o Why an RNA primer and not a DNA primer RNA is single stranded and can therefore complement the single stranded portion on the DNA Need additional enzymes to bring in nucleotides and build new stand Primer has to keep being added to the lagging strand The lagging strand is synthesized as short discontinuous fragments called Okazaki fragments Eventually you are going to come to the end of the lagging strand with a primer having an un replicated end so in order to not lose useful information telomerase enzymes come in to extend the un replicated end so you can finish off the lagging strand creates a redundant sequence to protect coded sequence from destruction telomerase is only active in gametes
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