Cell Organelles DSA Flashcards
The liver haptocyte has a high amount of this membrane
mitochondria inner membrane
the pancreatic exocrine cells has a high amount of this membrane
Rough ER membrane
What are the 3 topological categories
!) Nucleus and cytosol (communicate through nuclear pore
complex).
2) Organelles in secretory and endocytic pathways (ER, Golgi apparatus, endosomes, and lysosomes) (communicate through vesicles).
3) Mitochondria
what allows compartments to communicate with each other and cell exterior
fusion and budding
What compartments does the ER divide the cytoplasm into?
1) The luminal or cisternal compartment.
2) The cytoplasmic or cytosolic compartment
Rough ER imp functions
1) Proteins are modified &
Ribosomes assembled
2) Segregation of proteins for intracellular use and
3)Export from the cell (collagen, cell membrane proteins)
how are secretory proteins directed to the ER?
signal sequence
proteins that exit RER in vesicles travel to which portion of Golgi
cis portion
how does the smooth ER differ from rough ER?
- Lacks ribosomes
- Tubular cisternae
Functions of smooth ER
- Glycogen metabolism
- Lipid synthesis
- Phospholipid synthesis (other membranes)
- Detoxification
- Steroidogenesis
- Calcium regulation
- abundant in cells that make steroid or lipids
what are functions of the Golgi complex?
- Modification of carbohydrates attached to glycoproteins and proteoglycans
- Polysaccharide & oligosaccharide synthesis
- Synthesis of sphingomyelin and glycosphingolipids
- Sorting secretory products
- Packaging & storing secretory products into secretory granules or vesicles
what does the golgi complex mark lysomal enzymes with
mannose-6-phosphate (M6P)
the golgi dissembles during _____ and reassembles in _____
mitosis/meisosi and interphase
clathrin coated vesicles
transporting products from the Golgi apparatus to lysosomes or products from the exterior of the cell to lysosomes (like cholesterol)
COP (coat protein) I coated vesicles
transporting products between stacks of the Golgi apparatus
COP II coated vesicles
transporting products from the endoplasmic reticulum to the Golgi apparatus
what mediates clathrin binding to vesicular membrane
adaptin
in COP coated vesicles what leads to vesicle budding
coatomer
In COP coated vesicles what leads to disassembly of the vesicle coat
hydrolysis bound GTP changes ARF to GDP-bound leading to disassembly of the vesicle coat before the vesicles fuses with a target membrane
what causes the neck of a clatherin coated vesicle to be pinched off?
dynamin
what mediates clathrin binding to vesicle membrane?
adaptins
at what pH are lysosomes most active?
acidic pH
what is the lysosomal sorting pathway?
1) synthesis of lysomal enzyme
2) phosphorylation of lysosomal enzymes (mannose 6-P (M6P)
3) inter-golgi transporting vesicles
4) binding of lysosomal enzymes to M6P receptors
5) clathrin coated transporting vesicle
6) clathrin coat is lost. M6P receptor is recycled in Golgi and lysomal enzymes soared in primary lysosome
how to lysosomes maintain an acidic environment?
AtP-dependent H+ pump
primary lysosomes
- the storage site of lysosomal hydrolases
- No digestive events
- Homogeneous
- Inactive enzymes
secondary lysosomes
- engaged in a catalytic process
- Digestive enzymes
- Heterogeneous
- Active enzymes
what are the 3 pathways for intracellular degradation
1) phagocytosis
2) autophagy
3) receptor mediated endocytosis
how are lysosomes formed
- from the fusion of transport vesicle with endoscope
- early endoscopes mature to late endoscopes (precursors to secondary lysosomes)
what is an imp change in endosome maturation?
lower of internal ph to 5.5
Familial hypercholesterolemia
- Mechanism of cholesterol uptake is disrupted
- Characterized by elevation of LDL, the predominant cholesterol transport protein in the plasma
- Primary defect is mutation in gene encoding the LDL receptor
- High levels of LDL lead to atherosclerotic plaques
peroxisomes
-found in cytoplasm
-contains a number of enzymes that forms hydrogen peroxide (immediately broken down by catalase)
functions
•synthesis and degradation of hydrogen peroxide
•ß -oxidation of long-chain fatty acids
•bile acid and cholesterol synthesis
•detoxify alcohol
Zellweger spectrum disorder
- peroxisome biogenesis disorder
- defects in assembly of peroxisome
- defect in any 1 of 12 genes
- most serious= absent or reduced number of peroxisomes in cells
- present at birth, no cure, usually death in first year of life
which organelles originated from bacteria?
mitochondria and chloroplast
-adapted to generate and harness energy
are mitochondria more or less dynamic in high energy cells?
less dynamic
-can pack tightly
what is the evolution of mitochondria?
-fermenting bacteria to photosynthesis, to cellular respiration
changes in mt ___ have been linked to over 200 disease states
tRNAs
what does mutations of mt tRNAs prevent?
tRNA aminoacylation
what are 2 types of mitochondrial disease
- sometimes caused by mutations in the mt DNA that affect mitochondrial function
- Other causes of mt disease are mutations in the genes of the nuclear DNA, whose gene products are imported into as mt proteins as well as acquired mt conditions
