Noncytoskeletal Contents of Cytosol

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Non-cytoskeletal Contents of Cytosol
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Proteosome

• Barrel shaped multimeric complex of proteases
• Capped by regulatory particle containing ATPase.
• Digests ubiquinated proteins into smaller
  polypeptides of about 8 aa.

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Proteosome
8 aa Peptide
Misfolded protein
Ubiquitin
Ubiquinated protein
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Inclusions

• Stored material in cytoplasm resulting from
  either normal physiology or pathology
• Membrane limited storage vesicles (pigment
  granules, secretory granules), part of membrane
  organelle system

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Glycogen

• Carbohydrates are stored as glycogen granules
• By LM, stain acidophilic (associated protein) or
  by carbohydrate stains (PAS)
• by EM, appear as electron-dense particles

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Glycogen Storage Disease

• Inborn or acquired defect in enzyme required for
  glycogen utilization can produce abnormal
  glycogen accumulation

E
E
E
Glycogen Glucose
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Lipids

• Lipids (another storage form for energy)
• stored primarily by adipocytes
• ability to accumulate in other cells
• hepatocytes
• exist as free cytoplasmic droplets

Unlike in Wolmans disease, this lipid not in
lysosomes
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Nucleus
Very Important organelle but structurally
non-descript
Most of the important components are
submicroscopic
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Most of what we know about nuclear function is
from isolated nuclei and their components
Stores genetic material in long DNA molecules --
chromosomes
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• Visible parts of nucleus by light microscopy
• Nucleolus
• Euchromatin
• Heterochromatin

Chromatin DNA and its associated proteins
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• Visible parts of nucleus by electron microscopy
• Nucleolus
• Heterochromatin
• Euchromatin
• Nuclear membrane
• Nuclear pores
• Nuclear scaffold

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Chromatin organization clue to synthetic
activity of cell
Heterochromatic
Euchromatic
Does not indicate activity of synthesis of
specific protein