CTools021411lecture16

CTools021411lecture16 - Biology 172 Lecture 16: Monday,...

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Lecture 16: Monday, February 14, 2011 Biology 172 Today’s Outline Announcements Chromosome Structure Models for DNA Replication - Conservative model - Semi-conservative model - Dispersive model - Meselson-Stahl Expt DNA Replication - Basic Features - Initiation - Elongation - Termination DNA Repair •  Discussion this week: Central Dogma Quiz on Lectures 14, 15, 16
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Multiple levels of chromatin packing in euks 1. Nucleosomes (10-nm fiber) “beads on a string” basic unit of DNA packing “beads” = histone proteins have amino tail projecting outward “string” = double strand of linker DNA
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Interactions between histone tails of one nucleosome, linker DNA, and adjacent nucleosomes cause coiling 30-nm fibers form loops attached to a chromatin scaffold of non-histone proteins to make 300-nm fibers 2. Higher levels = 30 nm and 300 nm fibers ultiple levels of chromatin packing in euks
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Particular genes are always in the same place 3. Further packing produces metaphase chromosomes ultiple levels of chromatin packing in euks
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Chromosome Structure Levels of Eukaryotic DNA Packaging Nucleosome – basic unit of DNA packing Packing of looped domains into fibers and into condensed chromosomes Figure 18.2 Nucleosomes (a) Nucleosomes in chromatin Nucleosomes DNA 200 nm (b) Nucleosome structure Linker DNA H1 protein attached to linker DNA and nucleosome Nucleosome Group of 8 histone proteins 30-nm fiber 30 nm Protein scaffold Chromosome in its condensed form (the form it’s in during cell division)
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What does DNA do? 1. Copy Function - Faithfully copied during cell division DNA Replication 2. Expression Function - Encodes cellular products that determine phenotype RNA Protein Transcription Translation
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Today’s Outline Chromosome Structure Models for DNA Replication - Conservative model - Semi-conservative model - Dispersive model - Meselson-Stahl Expt DNA Replication - Basic Features - Initiation - Elongation - Termination DNA Repair
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Figure 4.9 DNA FORMS A TEMPLATE FOR ITS OWN SYNTHESIS. 1.
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This note was uploaded on 02/13/2012 for the course BIO 172 taught by Professor Clark during the Winter '08 term at University of Michigan.

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CTools021411lecture16 - Biology 172 Lecture 16: Monday,...

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