Download Nucleus/Nucleolus

Zachary Knott
Biology 101
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The nucleus is the cell’s control center
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It issues instructions to that control cell activities
It stores hereditary information
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Nuclear envelope: special kind of membrane that
bounds the surface of the nucleus
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Acts as a barrier between the nucleus and the
cytoplasm, but substances need to pass through it
Nuclear Pores: openings that form when the two
membrane layers pinch together
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The DNA of eukaryotes
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Form by dividing into several segments and
associating with protein
After cell division the chromosomes uncoil
forming threadlike structures called chromatin
The chromatin is then available for protein
synthesis
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Cite for several hundred genes that encode
rRNA
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rRNA: ribosomal RNA
Where ribosome subunits assemble
Nucleolus
Nuclear Envelope
Nuclear Pores
Chromosomes
Chromatin
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Huntington’s Disease
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Caused by a faulty gene being present on
chromosome 4
Having the faulty gene leads to damage of the nerve
cells in areas of the brain
Result: gradual physical, mental, and emotional
changes
The Huntington Disease Association
http://www.hda.org.uk/charity/whatishd.html
What is chromatin?
1.
A.
B.
C.
D.
A barrier between the nucleus and the cytoplasm
The place where ribosome subunits assemble
Uncoiled DNA that is used in protein synthesis
The cell’s control center
What is the role of nuclear pores?
2.
A.
B.
C.
D.
A special kind of membrane that bounds the surface of
the cell
It contains proteins that allow RNA in and out of a the
cell
Forms a barrier between the nucleus and the cytoplasm
allowing certain to pass through it
Openings that form when two membranes pinch
together