BCHM 3050 1st Edition Lecture 18 Outline of Last Lecture I How Sanger Sequencing Works II Southern Blotting Outline of Current Lecture I Triple Stranded DNA II Prokaryotes vs Eukaryotes III Transposons IV Comparing Genome Segments from Selected Organisms V General Characteristics of DNA Replication VI Meselson and Stahl VII Replication Origins VIII Summary of DNA Replication Current Lecture I Triple Stranded DNA a Triple helix facilitates role to enable crossing over recombination in meiosis b Polypyrimidine breaks off and forms additional bonds with other bases to form triple helix unstable form II Prokaryotes vs Eukaryotes a Eukaryotes have a lot of interruptions in its DNA discontinuous 95 of our DNA does not code for anything 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 b Do not have operons everything has their own control unit c Operons one control unit and everything in controlled by that unit found in prokaryotes III Transposons a Transposons jumping genes b Transposons cause random mutation some parts of DNA moves from one chromosome to another IV Comparing Genome Segments from Selected Organisms a Notice the amounts of non coding DNA in Humans Corn vs yeast E coli b Also notice the amounts of introns and especially the small amounts of coding specifically for genes in Human DNA c Finally Humans also have large amounts of DNA coding for tRNA s d Pseudogenes are only found in high organisms like humans not in prokaryotes e Empty spaces genes that code for tRNA V General Characteristics of DNA Replication a Chemically uni directional 5 3 b Semi conservative c Spatially bi directional DNA goes in both direction from a single point d Semi discontinuous e Adding new nucleotides to a growing chain of DNA is essentially DNA replication f Red leading strand made continuously g Green lagging strand made discontinuously made in pieces h DNA replication is considered semi discontinuous i Okazaki scientist who discovered lagging strands okazaki strand j VI Lagging does not refer to a lag in time or that the replication is slower in that stand Meselson and Stahl a Meselson and Stahl proved that DNA is semi conservative b Conserve 50 and make the other 50 from scratch c DNA replication happens in the nucleus of the cell at first DNA strands are separated d DNA can be labeled by its phosphorus nitrogen oxygen or carbon e Labeled nitrogen in the DNA of bacteria by labeling nitrogen in the food that they gave the bacteria f Labeled both strands of DNA with the heavy form of nitrogen N15 g Bacteria divide every 20 minutes the new DNA that was made had N14 instead of N15 for one strand DNA is semi conservative h Conservative is unequal sharing of DNA mother cell gives all DNA to one daughter cell and makes other daughter cell get DNA from scratch VII Replication Origins a Origins of replication are defined by certain sequences b All prokaryotes have the same origin most eukaryotes have the same origins c Break DNA open at the origin replication occurs in 2 directions both 5 to 3 d Eukaryotes have many origins sequences scattered throughout DNA breaks at different origin e Replication bubbles when DNA breaks at origin f VIII All strands are leading strands in this picture red Summary of DNA Replication a As leading strand is being made the zipper of DNA opens up more and more b Enzyme that carries out DNA replication is DNA polymerase c Polymerase needs a primer existing stretch of nucleotide d RNA primers e Memorize the functions of all of the proteins involved in DNA replication f Helicase opens the DNA from the origins of replication g DNA polymerase III enzyme that added nucleotides h RNA primase primers i DNA ligases joins the Okazaki fragments j DNA polymerase 1
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