L24 Cytosolic Disposal Systems Inculsions In Health And Disease Flashcards
What are lysosomes
Membrane bounded organelles that have acidic ph and contain hydrolytic enzymes
What do lysosomes do
Receive contents to be digested from late endosomes
And aid in digestion of phagocytosed microorganisms,cellular debris and cells but also excess or senescent organelles such as mitochondria and RER
How do substances destined for degradation reach lysosome
Phagosomes
Pinocytotic vesicle
Autophagosomes
How do phagosomes transport substances in to lysosomes
Phagocytosed material,contained within phagosomes move toward interior of the cell
Phagosome joins either a lysosome or a late endosome
Hydrolytic enzymes digest most of contents
What part of phagosome isnt digested
Lipids remain enclosed within spent lysosome now referred to as residual body
What is autophagy
▪️Self digesting mechanism responsible for removal of long lived proteins,damaged organelles and malformed proteins during biosynthesis by lysosome
▪️Organelles are surrounded by elements of ER and are enclosed in vesicles called autophagosomes
Either fuse with late enodosomes or with lysosomes
Whats the significance of autophagy
Regulate diverse cellular functions including growth,differentiation,response to nutrient deficit and oxidative stress, cell death and macromolecule and organelle turnover
How is autophagsome formation regulated
By dozens of autophagy related genes called atgs and is activated in response to diverse stress and physiological conditions
What happens if there is a mutation in atgs
Mutation leads to formation of double membrane vesicle which encasuplates cytoplasm,malformed protein,long lived proteins and organelles and then fuses with lysosome for degradation
What is lysosomal storage disorder
Certain individuals with hereditary enzyme deficiencies are incapable of completely degrading various macromolecules in to soluble by products
They accumulate in lysosome and enlarge in size and interfere with cells ability to perform function
What are proteasomes
Small organelles composed of protein complexes that are responsible for proteolysis of malformed ubiquitin tagged proteins
What is ubiquination
Process where several ubiquitin molecules are attached to candidate protein using ATP(through covalent attachment of a lysine side chain)
How is half life of protein determined
Influenced by N terminal residue of amino acid
Destabilized(arginine and acetylated alanine)=shorter half life
Stabilized(serine)=longer half life
PEST sequence=faster tagging and degrading
What are peroxisomes
Small membrane bounded self replicating organelles that contain oxidative enzymes such as urate oxidase and d amino acid oxidase
How do peroxisomes function
Catabolism of long chained fatty acids(beta oxidation) forming CoA as well as H202
