- chromatin
- eu chromatin : spread out for transcription
- heterochromatin: tight packed for storage
- nucleolus (-i)
- nuclear envelope
- double membrane structure
- nuclear pores control transport of material into and out of nucleus
- effective diameter of 9nm
- visible diameter of 70-80 nm
- actively transports proteins across
- nuclear lamina acts as support
- outer membrane continuous with rER
1.8 THE NUCLEUS [Hist]
| Size and structure of nucleus. |
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| Nuclear function. Communication between nucleus and cell. |
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1.8.1 Nuclear Structure [Cell Biol]
| DNA: long molecule, packing problem; histones, solenoids
and loops; relate to functions of DNA (replication, transcription, repair,
recombination). |
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| Interphase nuclei: chromatin (basophilic); eu- and
hetero-chromatin; constitutive and facultative heterochromatin (Barr
body); concept of condensed chromatin and gene inactivity. |
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| Nuclear envelope, defines eukaryote; inner and outer
membrane, perinuclear space; lamina; pores and problems of transport in
and out. |
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| Nucleolus, a ribosome-producing factory. |
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1.8.2 DNA and Information [Cell Biol]
| DNA as a container of the "genetic material". |
Classic experiments of DNA mediated transformation and
transduction of bacteria. |
| Chemistry of DNA makes it uniquely suited to its genetic
role. Nucleotide structure, and solving the structure of the double helix.
Base pairing and complementarity. DNA is a chemically stable molecule. |
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| Genetic code. DNA contains genes, which encode proteins. |
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| Mammalian genome (109 nucleotides in humans)
is complex; large fraction is "junk". Genes are programmed to be
expressed at different stages of development and in different tissues. |
Bacterial genome (106 nucleotides) is highly
streamlined: all genes are ready for action. |
1.8.3 Principles of Replication
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