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17 Cards in this Set
- Front
- Back
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Size of pores in nuclear envelope
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90 nm in diameter
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What is continuous with the outer nuclear membrane?
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Endoplasmic reticulum
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What is associated with the inner nuclear membrane?
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Nuclear lamina
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Lamins
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attach chromatin to the inner membrane of the nuclear envelope and participate in the breakdown and reformation of the nuclear envelop during cell cycle
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What happens when the lamina is phosphorylated?
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Initiation of nuclear disassembly into small vesicles (prophase of mitosis)
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What is the nucleolus responsible for?
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ribosomal RNA (rRNA) synthesis and ribosome assembly
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Nucleolus: Granular zone
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found at periphery; contains ribosomal precursor particles in various stages of assembly
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Nucleolus: Fibrillar zone
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centrally located; contains ribonuclear protein fibrils
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Nucleolus: Fibrillar center
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contains DNA that is not being transcribed
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Are histone proteins positively or negatively charged?
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Positively
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What are the two types of structures histones are important in forming?
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Nucleosomes and solenoid fibers
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What proportion of chromatin is euchromatin in a typical cell?
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90%, although only about 10% is being actively transcribed
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Where are the large ribosomal subunits synthesized?
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Nucleolus
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Where are the small ribosomal subunits synthesized?
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Nucleus
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Polysomes
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Single mRNA that is being translated by several ribosomes at once
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Free polysomes are the site of synthesis of proteins destined for...
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Nucleus, peroxisomes, mitochondria
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Membrane-associated polysomes are the site of synthesis of...
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secretory proteins, membrane proteins and lysosomal enzymes
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