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Endoplasmic Reticulum

Topic updated on 11/10/17 8:19am

 
 
 
Rough Endoplasmic Reticulum (RER) 
  • Structure 
    • composed of a lipid membrane with membrane bound ribosomes
    • lipid membrane is continuous with nuclear membrane
  • Function
    • synthesis of secretory proteins
      • e.g. peptide hormones
    • addition of N-linked oligosaccharides to peptides
  • Cell biology
    • RER is found in high concentration in
      • neurons
        • termed Nissl bodies
          • stain basophilic 
          • synthesize/secrete peptide neurotransmitters in prepackaged vesicles
      • pancreatic acinar cells
        • synthesize/secrete digestive enzymes
Smooth Endoplasmic Reticulum (SER)
  • Structure
    • lipid membrane without membrane bound ribosomes
  • Function 
    • steroid synthesis
    • detox of chemicals
      • makes compounds water soluble
      • two mechanisms
        • hydroxylation
          • via cytochrome P450 hydroxylase complex
        • conjugation
          • involves binding of polar moiety (e.g. glucuronate via glucuronyl transferase) to toxin
    • lipid metabolism
      • release of fatty acids from triglycerides
      • assembles lipoproteins for release
    • carbohydrate metabolism
      • gluconeogenesis
        • allows free glucose to be released into circulation during fasting by removing phosphate from glucose-6-phosphate
        • mediated by glucose-6-phosphatase
          • deficient in von Gierke's disease
            • glycogen storage disease type I
            • presentation
              • accumulation of glycogen in kidney and liver
                • hepatomegaly
              • hypoglycemia
  • Cell biology
    • found in high concentrations in
      • hepatocytes
      • kidney
      • adrenal cortex
      • corpus luteum
      • muscle
        • modified SER = sarcoplasmic reticulum
          • stores and releases calcium to mediate muscle contraction


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(M1.BC.21) Steroid hormone synthesis, lipid synthesis, and chemical detoxification are activities of which of the following? Topic Review Topic

1. Rough Endoplasmic Reticulum
2. Golgi bodies
3. Peroxisomes
4. Smooth Endoplasmic Reticulum
5. Nucleolus

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