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L312/Spring 2007 Lecture 17 Drummond March 22

L312/Spring 2007 Lecture 17 Drummond March 22. Important class notes: Sorry about the lost time and missing a class. Also apologies--exams are not graded. I’ll update when I can For today: Focus on Ch. 5 focus on pp 178-191 nucleosome and nuclear organization in the cell

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L312/Spring 2007 Lecture 17 Drummond March 22

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  1. L312/Spring 2007 Lecture 17 Drummond March 22 Important class notes: Sorry about the lost time and missing a class. Also apologies--exams are not graded. I’ll update when I can For today: Focus on Ch. 5 focus on pp 178-191 nucleosome and nuclear organization in the cell the initial material (DNA structure, pp 169-178) should be review Last time: concluded structural elements (microtubules, intermediate filaments, actin) don’t lose track of these as we go along--what happens to them Today: preparing for cytokinesis (cell division). Imagining a reversible cellular structure that can be ‘packed away’ and reconstituted. track organelles, filaments (modular structures), and connections focus on: nuclear structure and packaging of DNA: how is the information for cellular function packaged, regulated and accessed? Key topics for today: nucleosome structure and the histone code

  2. Scenario to consider: You go off to college; the ‘rents want to move to California! They want you to help them move all the stuff in the house!!! What key events must happen to prepare for the move? Who will be in charge? How will the events be controlled? Will everything be packed away during the move? How will the materials in the house be packaged? What will things look like in the new setting? Is there a specific sequence of events for unpacking? Is there an analogy to be developed between DNA organization and events in cellular division (mitosis)? Notes: be sure to think about this in terms of both function and information + events present, past and future

  3. 0.34 nm/bp Length of the human genome 5 x 109 bp x 0.34 x 10-9 m/bp =

  4. Gene sequences code for proteins Be sure you can connect regulation of transcription, translation and protein stability with extracellular signals mediated by GPRs, RTKs, SRHs.

  5. Look closely at dimensions; chromosomes are HIGHLY COMPACTED DNA (HOW?) What are: heterochromatin euchromatin What are the bands? Compare to boxes in move How MIGHT this relate to gene expression?

  6. Chromosome structure and compaction changes with the cell cycle What happens to the nuclear lamina? Minimal transcription and translation (where is ER/Golgi/nucleus/etc?) Expression to maintain Cellular function Analogy revisited

  7. Key structures within DNA (must remain accessible in compacted DNA)

  8. DNA compaction: focus on size scales and structures

  9. How is DNA compacted? What do these structures represent? Where might txn initiate? How does an RNA polymerase Read through these structures?

  10. How do nucleosomes pack into higher order structures? This has to be done in manner that is reversible and controllable with a memory

  11. Identification of the histone and nucleosome core components Distinguish Histones from nucleosomes

  12. DNA wrapped around a histone octamer Is this as tightly as DNA can be wound? Why would a positively charged polymer (DNA) stably wrap around proteins?

  13. Connecting “free” DNA with compacted structures--how are they related?

  14. What is heterochromatin? Building on the model that some chromosomal regions are ‘packed away”

  15. Answer these three questions: In the moving analogy, what is the real-world comparison for having gene next to a telomere vs. positioned in an accessible location? With that in mind, what is likely to be true of genes that normally reside near telomeres or in other heterochromatin structure? What might happen to a single human cell that experienced a recombination event that moved an important tumor suppressor gene next to a telomere?

  16. DNA is tagged with regulatory information at the level of the histone/nucleosome

  17. An introduction to the ‘histone code’ KNOW THIS!! What are these amino acids?

  18. Levels of organization within the nucleus

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