4. The endomembrane system Flashcards
list the components of the endomembrane system
nuclear membrane
endoplasmic reticulum (rough & smooth)
Golgi apparatus
lysosomes
name 3 functions of the smooth ER
- drug detoxification
- carbohydrate metabolism
- synthesis of fats, phospholipids and steroids
how does the smooth ER detoxify drugs
by adding charged- water soluble groups e.g. sulphate
what is the sarcoplasmic reticulum an example of?
what is its function
smooth endoplasmic reticulum
it isolates calcium ions from the cytosol which enables muscle contraction
how do calcium ions enter the sarcoplasmic reticulum
a SR bound ATPase - this pumps calcium ions into the SR lumen
what occurs in the rough endoplasmic reticulum
protein synthesis
glycolysation
define glycolysation
the addition of sugars and oligosaccharides
what is the function of the Golgi apparatus
mediates the flow of proteins from the RER to various parts of the endomembrane system, e.g. become lysosomes or enzymes
how many enzymes do lysosomes contain
what do these do
around 60 hydrolytic enzymes
these degrade almost all biomolecules
how are enzymes in lysosomes activated
once a lysosome fuses with its target, H+ ions are pumped in to lower pH and activate enzymes
what are the perfect conditions for lysosome enzymes
acidic (low pH)
lysosomes carry out autophagy, what is this?
recycling of worn out organelles
how do lysosomal storage diseases occur
partially degraded insoluble metabolites can accumulate within lysosomes when enzymes are defective
result in enlarged lysosomes that compromise cell function
give an example of a lysosomal storage disease, what happens
tay-sachs disease
- hexaminidase A enzyme deficiency= accumulation of the lipid ganglioside
- death occurs
