the ER and the golgi Flashcards
(26 cards)
what is the ER
network of phospolipid bilayer membranes arranged into tubes, vesicles & sacs
what are the flattened sacs called?
cisternae
what are the functions of the ER
Synthesis of intracellular & secreted lipids & proteins
Protein maturation
Storage within cisternae
what can the er store?
glyocgen and calcium
what are microsomes
ER vesicles formed when cells are disrupted
how can rough and smooth er vesicles be seperated?
separated by density- gradient centrifugation
why are the vesicles from the RER more dense than smooth ER
presence of ribosomes
does the smooth ER have ribsomes?
no
what is the smooth er involved with?
lipid metabolism
what are the 2 things the smooth er involved with?
Synthesis of membrane lipids, & steroid hormones from cholesterol
Detoxification of lipid drugs into excretable forms
ER vesicles
the ser is where the vesicles form and fuse with other orgnalles
what does the SER store?
calcium storage
what does the ser iniate>
Ca2+ signalling processes
channels in the PM
channels in the ER membrane
what does the ser terminate?
caclium signalling
Pump Ca2+ into ER ‘store
Pump Ca2+ out of cell
what is membrane lipid syntehsis?
involves lipid synthesis and essentail componenets of cell membranes
how are phosphlipids made?
made from FAs on cytosolic face of ER membrane
how is the membrane formed?
Growing Fatty Acid (FA) chains are elongated to 16 carbons [16C]
what enzyme helps the membrane lipid synthesis?
by acetyl CoA carboxylase
where does physophelration syntehsis occur?
occurs in the cytosol adjacent to ER membrane that is studded with proteins that act in synthesis
explain the process membrane lipid syntehis?
2 molecules of FA are esterified onto glycerol-3-phosphate to form phosphatidic acid (catalysed by GPAT enzymes)
An alcohol is then esterified onto the phosphate of phosphatidic acid to form a phospholipid
what does the rough er consist off?
cisternae which have ribosomes on their outer surface
what are the functions of the ER?
Functions in protein synthesis/maturation
What is each ribsome in the rer composed off?
50 different proteins (ribosomal proteins)
Several RNA molecules – the ribosomal RNAs (rRNAs
where does translation occur?
Occurs at the Ribosome, using mRNA as template
