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Lysosomal storage diseases
40 inherited diseases caused by defects in lysosome function
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Peroxisomes
- with processes that metabolize hydrogen peroxide (H2O2)
- also involved in fatty acid metabolism (oxidation)
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Properties of Eukaryotes: Synthesis
- ribosomes
- Rough ER
- Smooth ER
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Where are proteins made?
on Ribosomes
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Ribosomes free in cytoplasm
Proteins destined for organelles, cytosol
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Ribosomes bound to ER (rER)
- Proteins of the endomembrane system
- Proteins to be exported / secreted
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Ribosomes in energy-processing organelles
Some proteins in mitochondria, chloroplasts
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Endoplasmic Reticulum
organelle made of complex out-foldings of the outer nuclear membrane
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Rough ER
- has ribosomes attached
- modifies proteins and directs their transport
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Smooth ER
- lacks attached ribosomes
- involved in lipid and carbohydrate synthesis, steroid hormone production, detoxification
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Export - thru the Endomembrane System
- Synthesis on rER or in ER
- Transport to Golgi
- Glycosylation
- Exocytosis / Secretion
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Vesicular transport
transport vesicle forms at donor compartment, goes to donor compartment to deliver membrane and content
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Golgi Apparatus
- organelle containing stacks of membranes
- functions in modification and targeting of proteins
- generates vesicles that go to many destinations
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The Endomembrane System, The Secretory Pathway
An integrated network of molecular trafficking
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Organelles of the Secretory Pathway
- ER
- Golgi
- plasma membrane
- lysosome
- endosome
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Animal pancreatic cell
Exports digestive enzymes
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Exocytosis
vesicle membrane is added to the plasma membrane and contents are released from the cell (secretion)
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Endocytosis
internalization of plasma membrane and extracellular contents are internalized
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Receptor - mediated Endocytosis
- Recycling of receptors (proteins) from lysosome back to plasma membrane; e.g. during uptake of cholesterol from blood stream
- Some receptors are degraded in the lysosome
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Ribosomes bound to rER
- Proteins of the endomembrane system
- Proteins to be exported / secreted
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Co translation transport
protein is synthesized and transported into ER at the same time
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Ribosomes free in cytoplasm
Proteins destined for organelles, cytosol
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Post-translational transport
protein is completely synthesized and released from the ribosome before transport
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Proteins have targeting signals
a molecular address tag
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Secretory pathway proteins are targeted to the ER by ...
a signal sequence
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Protein sorting and vesicle transport
- 1. Proteins are tagged
- 2. Proteins are sorted
- 3. Vesicles bud
- 4. Proteins interact with receptors
- 5. Delivery
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Sorting within the secretory pathways occurs via ...
sorting signals
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Energy-processing chemical reactions
- cellular respiration in mitochondria
- photosynthesis in chloroplasts
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Two membrane systems
- Outer membrane acts as boundary
- Inner membrane with energy reactions
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Semi-autonomous organelles
- With some of their own DNA and Ribosomes
- Codes for some of their own proteins
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Chloroplast (plants and algae)
- organelle that carries out photosynthesis
- composed of three membranes (2 systems)
- possesses its own DNA and ribosomes
- a kind of plastid ... others include chromoplasts (pigments) and amyloplasts (starch)
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Mitochondria and bacteria are ....
similar in size
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