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The Nucleus and Ribosomes. By M. Wickenheiser. Nucleus. Is surrounded by the nuclear envelope A double membrane perforated by pores that regulate the movement of large macromolecules between the nucleus and the cytoplasm. Is the largest organelle in the cell Directs protein synthesis .
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The Nucleus and Ribosomes By M. Wickenheiser
Nucleus • Is surrounded by the nuclear envelope • A double membrane perforated by pores that regulate the movement of large macromolecules between the nucleus and the cytoplasm. • Is the largest organelle in the cell • Directs protein synthesis
Nuclear Lamina • Lines inner membrane • Is a layer of protein filaments that helps to maintain the shape of the nucleus
Chromatin • Is where cell’s DNA along with associated proteins diffuse into a mass • Located in the nucleus
Chromosomes • Thin chromatin fibers that coil up to become thick enough to be a separate structure. Only coil when cell is about to divide. • Inside the nucleus • Provides DNA for the mother and daughter cell.
Nucleolus • Prominent structure within the nondividing nucleus • Location • Center of nucleus • Appears through the electron microscope as a mass of densely strained granules and fibers adjoining part of the chromatin • A special type of RNA called ribosomal RNA is synthesized and assembled with proteins imported from the cytoplasm into the main components
Ribosomes • Particles made of ribosomal RNA and protein • Organelles enclosed in membrane • Function • Protein synthesis • Locations • Free Ribosomes are suspended in the cytoplasmic locales • Bound Ribosomes are attached to the outside of the endoplasmic reticulum or nuclear envelope. • Both are structurally identical and can alternate between the two roles