L 24 Cytosolic Disposal Systems Inclusions in Health and Disease Flashcards
What are lysosomes?
They are membrane bound organelles that contain hydrolytic enzymes and have acidic PH
How many enzymes does a lysosomes contain and mention 4 of them?
It contains 40 different types of acidic hydrolases such as proteases lipases sulfatases and nucleases.
Where are the enzymes of a lysosomes synthesized?
They are manufactured in the rER and packed in golgi complex and released in vesicles from the trans golgi network
Function of lysosomes?
They aid in digestion of phagocytosed microorganisms,cell debris and cells but also organelles in excess or in senescent like mitochondria and RER. The various enzymes digest the engulfed material into small soluble substances that are transported out of lysosomes by carrier proteins into the cytosol and either reused or exported out of the cell
What are phagosomes?
They are vesicles that contain the phagocytosed/engulfed material and move towards the interior of the cell where it fuses with lysosome or late endosome. Hydrolytic enzymes break down most of the phagosomes content specifically proteins and carbs but not lipids so they remain in the lysosome which is now referred to as residual body
What is autophagy?
Self devouring of senescent organelles like mitochondria and RER.
How is the autophagosome formed?
The organelles to be degraded are surrounded by endoplasmic reticulum and become enclosed in a vesicle called autophagosome. Autophagosome either fuse with late endosome or lysosome and share the same fate as the phagosome.
What is the significance of autophagy?
Regulates diverse cellular functions like growth, differentiation, response to nutrient deprivation, macromolecules, cell death, organelle turnover and oxidative stress. And responsible for the removal of long lived proteins damaged organelles and malformed proteins
Mechanism of autophagosome?
Autophagosome formation is regulated by dozens of autophagy related genest Atgs.
Mutation leads to formation of double membrane vesicle that encloses the cytoplasms malformed proteins. Long-lived proteins and organelles and then fuse with lysosomes for degradation.
Autophagy regulation?
Autophagy is activated in response to diverse stress and physiological conditions like food deprivation hyperthermia and hypoxia which are all major environmental modulators for aging and are conditions that induce autophagy
Autophagy and disease?
On starvation, autophagy is increased greatly allowing the cell to degrade proteins and organelles to obtain amino acides fatty acids and nucleotides. Autophagy has an anticancer role but also prevent death of cancer cells. Autophagy is important for bacterial and viral infections neurodegenerative disorder myopathies and cardiovascular disease
what are proteosomes?
they are small organelles composed of protein complexes that are responsible for the proteolysis of the malformed ubiquitin tagged proteins. it monitors the protein content of the cell and ensure degradation of unwanted proteins like excess enzymes malformed proteins and proteins encoded from viruses are destroyed. the process of cytosolic proteolysis is carefully controlled and requires the candidate proteins to be tagged
what is the process of ubiquitination?
its the process where a ubiquitin molecule (76 amino acids) are attached to candidate protein using ATP. its then degraded by proteomes and ubiquitin molecules detached and renters the cytosolic pool to be reused.
protein degradation in health and in disease?
ubiquitin molecules attach covalently to the lysine side chains. the amino acid composition at the amino terminus determines how quickly the protein will be ubiquinated. and determines its half life
the half life of proteins?
CRYSTALLIN——–> very long half life found in the lens of the eye
HEAMOGLOBIN——–> 4 months half-life
ORNITHINE DECARBOXYLASE———–> 11 minus half life
