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13 Cards in this Set

  • Front
  • Back
Early endosome characteristics
-located close to plasma membrane
-involved in receptor recycling
-transport of early endosomes to late endosomes takes place through endosomal carrier vesicles
Late Endosome characteristics
-Lie close to Golgi or nucleus
-Receive materials for digestion
-arise from early endosomes or fuse with hetero/autophagosomes
Series of events to form a lysosome
1. Take material in via endocytoses in clathrin coated pit
2. loses clathrin joins w/ early endosome (pH=6) which sorts contents
3.early endosome bring material to late endosome (pH=5.5)
4.Hetero/autophagosomes can join w/late endosomes forming lysosome (pH=5)
Lysosome characteristics
-formed from late endosomes
-pH=5-6 maintained by ATP driven H+ pump
-Contain hydrolytic enzymes i.e. nuclease, proteases, lipases
-like small stomachs
-special membranes to protect from enzymes
- membrane prevents leakage but allow digested materials to diffuse into cytosol
-permeability may change
-end products of lysosomal digestion are residual bodies or cleared out
Peroxisome characteristics
-small, vary in size and shape
-electron-dense contents usually contain crystallin and cylindrical bodies
-contain catalase but no acid-phosphatase, produce H2O2
-location: liver cells, kidney tubules
-fxns: perform oxidative reactions, energy is then used for metabolic processes or is dispersed as heat, detox ethanol
-a role in gluconeogenesis
consists of:
microfilaments, intermediate filaments, microfilaments, associated intercalated proteins.
-microfilaments, microtubules have similar structure in all cells, but intermediate filaments vary in composition from cell to cell.
contractions, rigidity, mechanical strength, give shape to cell, intercellular transport/movement, chromosomal migration.
microfilament (actin and myosin)
-actin filaments:
8nm, G and F actin form helices, only 1/2 cellular actin is found in filamentous form, crosslinked by actin binding proteins into parallel bundles and gel like networks
slide along each other during muscle contraction
Intermediate Filaments
-helical array of tetramers formed by elongated filamentous protein monomers
-abundant in cells subjected to mechanical stress
provide mechanical strength to cell, shape, make different cells unique
-in 6 major types:
keratin, desmin, vimentin, glial filaments, neurofilaments and nuclear lamins
-hollow tubules
-protofilaments formed of alpha tubulin and beta tubulin subunits (13 of these combine to form a microtubule)
positive: polymerizing and growing
negative: depolymerizing
-fxns of MAPs (microtubule-associated proteins):
prevent depolarization and mediate interactions w/ other cell components, dyneins and kinesins are MAPs
centrioles pull chormosomes apart, provide binding sites for MAPs, mediate organelle, and vesicle movement, structural components of basal bodies, maintenance of shape in erythrocytes and platelets
-barely visible w/ LM
-consist of 2 centrioles at right angles to each other
-components of 9 groups of triplets (1 complete, 2 incomplete)
Cytoplasmic Inclusions:
do not participate in cell metabolism

-present in liver, heart and skeletal muscle cells
-stained w/ bests caramine or PAS
-alpha particles assemble as groups in rosette config
-beta particels are individual units
-in adipose cells, hepatocytes and sterid producing cells
-non-membrane bound droplet
-imp. energy resource
-dark brown to black
-membrane bound melanosomes in melanocytes
-may be transferred to keratinocytes
-due to hemoglobin degradation
-golden brown due to iron, formed of ferritin
spleen, liver, bone marrow, hemal nodes
-aging pigment in cardiac cells, neurons
-residual product of lysosomal activity