Cell Bio III Flashcards
Macropinocytosis
- Actin-based
- Nonspecific ingestion of fluid and solutes
- Can be triggered by bacteria
Clathrin-mediated endocytosis
- Occurs at clathrin-coated pits
- Dynamin GTPase required to pinch off vesivle.
- Can be mediated by receptors - process to endocytose specific molecules
Phagocytosis
- Ingestion of large particles, mediated by receptors
- Dependent on actin, not clathrin
- Phagosomes fuse with lysosomes
Regulated pathway of exocytosis
stores product
Constitutive pathways of exocytosis
constantly forms secretory products to go through exocytosis. Does not store
Porocytosis
Quantal release of neurotransports
Ribosomes
- Contain E, P, and A sites
- Have large and small ribosomal subunit
- Required for protein synthesis
rER
- Cisternae are studded with polyribosomes
- Basophilic
- Continuous with outer membrane of nuclear envelop
Function of rER
- Synthesis of proteins for secretion, insertion into membranes, and lysosomal proteins
- Synthesis of sER enzymes
- Protein modification - cells with a lot of protein syntheiss have a lot of rER
Glycosylation
Attaches one carbohydrate to another, helps with protein folding
ER stress
Accumulation of unfolded/misfolded proteins in the ER cisternia
Unfolded protein response
- Increased chaperone synthesis to help repair misfolded proteins
- Decreased synthesis of proteins
- Misfolded proteins get exported from ER to cytosol where they are tagged for degradation by proteasomes
- Activate caspases - apoptosis
Alpha1-antitrypsin deficieny
mutant protein aggregates in ER
Function of sER
- Steriod synthesis
- Cholesterol homeostasis
- Synthesis of phospholipids
- Glycogen metabolism
- Drug detox
- Storagem release, and uptake of calcium ions in striated muscle
Von Gierke’s disease
- Glycogen storage disease
- Mutation at either g-6-p transporter or glucose-6-phosphatase
What can increase the volume of sER
phenonbarB, in alcoholics
Co-translational translocation of proteins
- Have mRNA bound in ribosome. Also bound is protein strand with a recognition strand
- Signal recognition molecule sees recognition strand then binds
- Whole complex binds to signal recognition receptor
- Translocon gets “uncorked”
- Protein sequence can enter lumen of rER
- After protein sequence enters, signal peptidase cleaves off signal sequence, releases mature protein into rER lumen