3. “Nucleus” is a Latin word meaning Kernel
It is the “CONTROL CENTER” of the cell
It was First cell organelle to be discovered
It is membrane bound organelle found in eukaryotic cells
Main functions are
- to maintain the integrity of genes
- to control the activities of the cell by regulating gene expression
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5. Also known as perinuclear envelope, nuclear membrane or
karyotheca
Encloses the nucleus and separates the cell's genetic material
from the surrounding cytoplasm
It is a lipid bilayer
Consists two cellular membranes, an inner & outer membrane,
arranged parallel to one another and separated by 10-50(nm)
of space
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7. 6 nm thick
Faces cytoplasm and is continuous at certain sites with the
RER
A loosely arranged mesh of intermediate filaments (vimentin)
Ribosomes stud the cytoplasmic surface of the outer nuclear
membrane
Ribosomes synthesize proteins that enter the perinuclear
cisterna (space between two membranes 20-40nm wide)
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8. Faces the nuclear material
Primary site for location of inner nuclear membrane proteins
IMP
Inner membrane proteins – LAP2, SUN1, EMERIN, MAN1,
LBR (used during formation of NE during mitosis as well as
some role in transcriptional activity)
Outer and inner membranes are fused at the nuclear pore
complex sites
Inner Membrane is supported underneath by Nuclear lamina
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10. Nucleolus is the discrete densely
stained structure found in nucleus
It is a nuclear inclusion that is not
surrounded by a membrane
Present in cells that are actively
synthesizing proteins
Its size depends on metabolic
activity of cell
Average size .5-5um in dia
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11. It is generally detectable when the
cell is in interphase
Synthesis of RNA and its assembly
into ribosome precursors- main
function
More than one nucleolus can be
present in the nucleus
3nucleoli , nucleus of the
spinosum cell layer of skin
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13. Anucleated cells- which contain no nuclei, thus has no
capacity to divide eg.
RBC Platelets
Polynucleated cells- With multiple nuclei eg.
Species of protozoa
Some fungi
Intestinal parasites like giardia
Giant cells in inflammation
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