Lecture 8 - Lecture8...

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Lecture 8 Difference between a Northern blot and microarry is? Involve RNA Involves determining whether a particular RNA species is present in a particular sample and at what level it is expressed at. Quantitative methods for looking at the relative expression pattern of various RNA that are encoded by a certain gene The difference in a northern blot is the actual experimental sample are run on the agarose gel, then transfered to filter paper, and the gene whose expression your interested in is the probe. have to look at each gene separately Microarray experiment is reversed, all the genes you are interested in and want to examine are spotted on the chip either short oligos that are complementary to the message or the cDNAs of those message. And the RNAs are probed. probe - who ever has the tag that your experimental design is detecting in both experiments the goal is to determine the level of RNA for a specific gene Microarray allows you to examine tens of thousands of genes at once where North- ern blot allows you to look at many tissues but only one gene at a time. Both give quantitative information, so the signal shows greater hybridization in that band or spot, so there had to be more RNA in the sample To make it quantitative which nucleic acid should be in excess for a chip, should it be the oligonucleotide on the chip or should it be the RNA your hybrid- izing onto the chip? RNA, otherwise it would saturate the chip so you wouldn’t have a quantitat- ive result Microarray some gene is covalently attached to the slide. Why does every spot in microarray have a different intensity? the intensity correlates to the level of expression. greater intensity means that there is higher expression tells how much of the probe hybridized to the given gene In any given genome, a replicon of the unit between the origin and the termination In phage or e. coli there is only one origin, and the replicon is the entire genome In larger organisms, it is required to have many replicons growing at the same time to ensure that replication can occur in the alloted time. So the human genome is broken into many replicons Some genomes have an origin that has a unidirectional fork, meaning the direction that your unwinding the parental DNA (fork) is moving in one direction. (usually viral genome) In other types of genomes replications is bidirectional, meaning that there is a fork movement in both directions. And have two different replication apparatus as- sembled on two different sides moving in two different directions simultaneously. (usually bacterial)
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RNA polymerase requires NTPs and a template needs a template to tell the polymerase what should I synthesize and where is the complementary base. Without a template it does not know how to synthesize the polynucleotide chain. Uses 4 ribotriphosphates
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Lecture 8 - Lecture8...

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