Biology 1002B Chapter Notes - Chapter 2.3: Lysosomal Storage Disease, Mitochondrion, Inner Mitochondrial Membrane
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• Golgi Complex
o Responsible for final modification, sorting, distribution of proteins and lipids
o Separated cisternae unlike ER cisternae, typically 3-8
o Number and size of Golgi depends on if cell is highly active in secreting
proteins
o ER vesicles contact cis face (near nucleus) and fuse with Golgi
o Modified proteins bud off from Golgi at trans face (near plasma membrane)
o Determines if proteins are secreted, embedded in plasma membrane, or
placed in lysosomes by adding labels during modification
o Secretory vesicle: carry proteins to release them via exocytosis
o Endocytic vesicle: contain proteins from outside via endocytosis
• Lysosomes
o Vesicle that contains 30 hydrolytic enzymes for digestion of complex
molecules
o Found in animals but not plants
o Plants have vacuole that carry out lysosome functions
o Formed by budding from Golgi and enzymes are synthesized in rough ER
o pH within lysosome is 5 while cytosol is 7.2, so hydrolytic enzymes work
optimally in lysosome
o Autophagy: digestion of organelles that are not functioning correctly
o Play a role in phagocytosis and break down bacteria
• Large vesicle contains engulfed bacteria
• Lysosomes fuse with vesicle and release enzymes to degrade them
o Lysosomal storage disease: one hydrolytic enzyme is absent so that substrate
accumulates in lysosomes
o Tay-Sachs disease: caused by lack of enzyme that hydrolyzes fatty acid
derivatives found in brain
2.3e Mitochondria Are the Organelles in Which Cellular Respiration Occurs
• Cellular respiration: energy-rich molecules are broken down to water and CO2 by
mitochondrial reactions
o Energy released by cellular respiration is used to generate ATP
o Mitochondria require oxygen for this
• Structure
o Outer mitochondrial membrane is smooth and covers outside of organelle
o Inner mitochondrial membrane surrounds matrix and is expanded by folds
called cristae
o ATP-generating reactions occur in cristae and matrix
• Matrix contains DNA and ribosomes that resemble equivalent structures in
bacteria
o This suggest that mitochondria originated from ancient bacteria
o During evolution of eukaryotic cells, these bacteria became permanent
residents inside the cells
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