Chapter 7 Molecular Organization of Chromosomes

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Chapter 7Molecular Organization of Chromosomes
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The range of genome sizes in the animal plant
kingdoms
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DNA can assume alternative conformations such as
partially melted or supercoiled states
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Mechanism of action of a topoisomerase
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Mechanism of folding of a bacterial chromosome
There are many supercoiled loops (100 in E.
coli) attached to a central core. Each loop can
be independently relaxed or condensed.
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Packing of DNA in an eukaryotic cell involves
wrapping around a core of basic (positively
charged) proteins called histones
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Steps in the folding of DNA to create an
eukaryotic chromosome
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The rate of renaturation of single stranded DNA
depends upon the concentration and sequence
complexity
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The rates of renaturation of DNAs with different
kinetic complexities
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DNA of an eukaryotic cell has several components
with different kinetic complexities
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DNA with low kinetic complexity is located in the
middle (near the centromere) and at the ends
(near the telomeres) of a chromosome
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Structure of the centromere in a Saccharomyces
chromosome
The centromere DNA has 4 centromere determining
elements (CDEs)
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Replication of telomere DNA repeats
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Mechanism of replication of telomere DNA by the
enzyme telomerase
The enzyme telomerase has a RNA molecule that
serves as the template for telomere DNA synthesis.
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Telomerase has protein and RNA components
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Proposed 4-stranded structure of telomere DNA in
two protozoans
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Hydrogen bonding structure of G quartet