(1) DSA: Cell Organelles Flashcards
Role of Endoplasmic reticulum?
- Protein synthesis
- Lipid synthesis
- Protein folding
- Storage of calcium
Role of lysosomes?
Digest organelles and biomolecules
Role of peroxisomes?
Oxidation reactions
What are the 3 Topological compartments of the cell?
- Nucleus and cytosol
- Secretory pathway (ER, Golgi, Endosomes, Lysosomes)
- Mitochondria
Membrane ______ and ______ allows the lumen of these compartments to communicate with each other and with the cell exterior
budding; fusion
What are the two compartments of the endoplasmic reticulum?
- Luminal/Cisternal compartment
- Cytoplasmic/cytosolic compartment
Cells that make _______ proteins have lots of RER
secreted
Protein synthesis:
How does it occur b/w ribosomes and the RER?
- Ribosomes attach to ER
2. Secretory proteins are directed to ER based on SIGNAL SEQUENCE
Most proteins exit the RER in vesicles transported to the ____ portion of the Golgi apparatus
Cis
How is SER different from the RER?
SER…
- Lacks ribosomes
- Tubular cisternae
What is the role of lysosomes?
Cellular suicide organelles
- digest
- born from endosomes and golgi vesicles
Vesicle transport mechanisms:
What are the two types of coated vesicles?
- Clathrin-coated vesicles
2. COP-coated vesicles
Where do CLATHRIN COATED vesicles travel?
Golgi–> Lysosomes
Where do COP-COATED vesicles travel?
Travel within stacks of the golgi apparatus (COP1)
From ER to the Golgi (COPII)
What is the function of dynamin?
Surrounds the neck of the invaginated coated pit, causing the neck of the vesicle to pinch off from the plasma membrane
Lysosomal enzymes are most active at what pH?
ACIDIC pH
What are the IMPORTANT 2 steps of lysosomal sorting?
- Phosphorylation of lysosomal enzymes (M6P)
4. Binding of lysosomal enzymes to M6P receptor
What do lysosomes contain that maintains an acidic intralysosomal environment?
ATP-dependent H+ pump
What is a primary lysosome?
No digestive events, inactive enzymes
What is a secondary lysosome?
Engaged in catalytic process
Function of the golgi?
Post-translational changes on proteins and lipids
Role of mitochondria?
- Makes ATP
- Signaling
- Cell differentiation and death
Cells that make _______ proteins have lots of RER
Secreted
The SMOOTH ER is continuous with the RER but differs in two ways:
- Lacks ribosomes
- Tubular cisternae
What signals to the golgi to make lysosomal enzymes?
Mannose-6-phosphate
Golgi apparatus/complex:
What does retrograde traffic refer to?
Vesicles traveling from golgi to ER
Golgi apparatus/complex:
What does anterograde traffic refer to?:
Vesicles traveling from Golgi toward exiting cytoplasm
What is the fate of a CLATHRIN coated vesicle?
Golgi–> lysosomes/exterior of cell
What is the fate of COP-coated vesicles?
Products travel b/w stacks of Golgi (COP-I)
Products travel from ER to Golgi (COP-II)
What are the 3 pathways for intracellular degradation?
- Phagocytosis
- Autophagy
- Receptor-mediated endocytosis
*IMPORTANT change to endosome maturation?
Lowering of internal pH to 5.5
What is familial hypercholesterolemia?
Mechanism: cholesterol uptake is disrupted
- Elevation in LDL (predominant cholesterol transport protein in plasma)
- High levels lead to atherosclerotic plaques
Functions of peroxisomes?
- Synthesis and degradation of hydrogen peroxide
- Beta-oxidation of long chain fatty acids
- Bile acid and cholesterol synthesis
- Detoxify alcohol
What are Zellweger spectrum disorders caused by?
Peroxisome biogenesis disorder
- Absence or reduced # of peroxisomes
- Congenital
- No cure, death within first year of life
Mitochondria originated from…
bacteria
Mitochondria evolved to eventually…
retain own DNA
