last  page PLNT3140 Introductory Cytogenetics
Lecture 9, part 1 of 4
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September 28, 2017



Learning Checklist:

A. Eukaryotic genomes are huge, which requires them to have elaborate mechanisms for replicating and packaging their DNA.
B. Be able to explain why
gene expression and DNA replication are fundamentally in conflict, and how the design of the eukaryotic cell resolves this conflict.
C. Eukaryotic chromosomes are DNA molecules packaged by histone and non-histone proteins, which, together with DNA form chromatin. Know the basics of histones, how they form a histone core particle.
D. Know the basics of how DNA coils around histone octamer particles to form nucleosomes.
E. Know the basics of the chromatin structure in solenoids, or 30nm fibers are coils of chromatin.
F. Know how histones are replaced by protamines in spermatogenesis.

G. Understand the experiments which demonstrate that for transcription to occur,  the chromatin structure of a gene must be 'open', that is, accessible to the transcription machinery.
H. Understand the experiments that demonstrate that transcriptionally active DNA remains associated with histones.

Cytogenetics could be said to be a hubristic pursuit. The goal of cytogenetics is nothing less than the understanding of the eukaryotic genome as a dynamic, functioning unit. This seemingly quixotic enterprise has culminated with the complete map and DNA sequence for a growing number of species, including yeast, Caenorabiditis elegansDrosophila, Arabidopsis thaliana and man.
The next 3 lectures will concentrate on what we know today about chromosomal and nuclear structure and function. Later in the course, we will focus on methods for mapping and sequencing eukaryotic genomes.

Preview: Summary of Chromosome Structure
from Lodish et al. Molecular Cell Biology

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last  page PLNT3140 Introductory Cytogenetics
Lecture 9, part 1 of 4
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