Orbital compartmentation

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Cytosol[edit | edit source]

It is the cytoplasm itself, i.e. liquid part without organelles. Metabolism takes place here:

Among other things, part of the heme synthesis and urea pathways, purine and pyrimidine metabolism takes place here. Cell Organelles - 1. Nucleus, 2. Nucleus, 3. Ribosome, 4. Vesicle, 5. Rough Endoplasmic Reticulum, 6. Golgi Apparatus, 7. Cytoskeleton, 8. Smooth Endoplasmic Reticulum , 9. mitochondria, 10. vacuole, 11. cytosol, 12. lysosome, 13. centriole

Mitochondria[edit | edit source]

It belongs to the important organelles of cellular metabolism. Metabolism takes place here:

  • saccharides: PDH, beginning of gluconeogenesis (conversion of pyruvate to oxaloacetate)
  • fatty acids: β-oxidation of MK (Lynen's spiral), ketobodies synthesis (only liver cells), degradation of ketobodies (only extrahepatic tissues)
  • amino acid: oxidative deamination of glutamate and some transaminations

The junction of all catabolic reactions is located here - Krebs cycle. The respiratory chain and oxidative phosphorylation take place on the inner mitochondrial membrane. Mitochondria are also important for heme and urea synthesis.

Rough endoplasmic reticulum[edit | edit source]

It has an important role in proteosynthesis (translation of mRNA takes place here). The synthesized proteins are subsequently post-translationally modified (oxidation, cleavage, methylation, phosphorylation, glycosylation).

Smooth endoplasmic reticulum[edit | edit source]

It has a significant role in the synthesis of TAG and phospholipids. Enzymes for "elongation" (up to a maximum length of 24 carbons in nervous tissue) and "desaturation" (up to a maximum distance of 9 carbons from the carboxyl group) of fatty acids are located here. Part of steroid synthesis and biotransformation of xenobiotics takes place here. In some tissues there is a localized glucose-6-phosphatase which converts glucose-6-phosphate into glucose.

Golgi Apparatus[edit | edit source]

Post-translational modification of proteins (e.g. glycosylation), further sorting of proteins and formation of ``secretory vesicles takes place here.

Lysosomes[edit | edit source]

It is used for the hydrolytic cleavage of proteins, carbohydrates, lipids and nucleic acids.

Peroxisomes[edit | edit source]

It serves to degrade MK with a long chain (from 20 carbons).