Lecture 7 Flashcards
Endosomes: Form and Function
Endosomes
Converges what?
Property?
Converges biosynthetic and endocytic pathway
-low pH of 6
-is the recycling and sorting compartment
Why does endosomes have low pH and what is it’s function?
Low pH is caused by the proton pump which acidifies the content. Low pH promotes dissociation of receptors and their ligands
what is LDL
LDL is low-density lipoproteins, they carry cholesterol to be used for biosynthesis
Hypothesis for endosome compartments
Stable which transfers down cargo vesicle and bring back empty ones
Maturation is where early fuses to late fuses to lysosomes and recycles vesicle back u
Horseradish Peroxidase and what does it catalyze?
-good for tracing
-catalyze polymerization of DAB which forms a product that is visible with EM
Heterotypic Fusion
Fusion of compartments with different composition
eg. vesicle to ER
Homotypic
Fusion of same composition compartments
eg. Golgi to Golgi
Homotypic Fusion involves?
Rab GTPase with GEF, tethers, SM and R- and Q-SNAREs
Multivesicular Bodies or late endosomes
Internalized molecules for degradation becomes packaged into large spherical structures
2 main functions of Light Microscopy
Magnify and add contrast
Refraction
Is when light’s velocity changes when medium changes
How does oil immersion increase resolution?
It allows light to not have internal reflection and focuses the rays to just inside the immersion compared to just air
Phase-Contrast Microscopy
Enhances phase shift by increase interference.
Different protein concentration have different refractive index
Do late endosomes mature or fuse into lysosomes?
Experiment was used to confirm that late endosomes FUSE
HRP was used to chase. All HRP was internalized by lysosomes which are then inactivated by DAB. All late endosomes were not maturing and could not fuse.
How do endosomes sort?
Geometry and biochemically
