Endomembrane system Flashcards
What is the endomembrane system comprised of?
Nuclear membrane, endoplasmic recticulums, golgi apparatus, lysosomes
What is the role of the smooth endoplasmic reticulum?
Phospholipids are manufactured
Drug detoxification,
Carbohydrate metabolism
Synthesis of fats
What is the SER responsible for in hepatocytes?
The breakdown of stored glycogen and release glucose
What is the sarcoplasmic reticulum?
Highly specialised muscle cell SER which sequences calcium ions from the cytosol
What forms inside the tubular SER?
calcium
Describe the calcium pump
SR bound ATPase which pumps calcium ions into SR lumen
What is muscle contraction triggered by?
A change in the action potential in muscle cell plasma membrane which triggers the SR the release calcium ions into the muscle cytosol.
How does muscle contraction take place?
The calcium ions bind to a protein complex of tropomyosin and troponin which normally blocks the interaction between the myosin heads and actin. Calcium ions attach this complex changing its conformation. This allows the myosin heads to interact with the actin filaments
What proteins are synthesised in the RER?
extracellular proteins
membrane proteins
lysosomal proteins
glycoproteins
Where does protein synthesis of RER destined proteins begin?
In the cytosol
What do ribosome synthesising proteins have to have to become attached to the RER?
Specific signal peptide sequence
What stops translation in the cytosol?
When SRP attaches to the signal peptide
What does glycosylation mean?
Addition of sugars or oligosaccharides
