L19 - The secretory pathway Flashcards
Describe the structure of the endoplasmic recticulum.
The ER is connected to the nuclear envelope. It forms hollow tubes and flattened sacs.
The two types of endoplasmic reticulum are the RER and SER.
What are the functions of the endoplasmic reticulum?
- Quality control
- Synthesis
- Storage
- Detoxification
What is the SER and its function?
There are no ribosomes in the smooth endoplasmic reticulum.
It is for…
- Phospholipid and cholesterol synthesis.
- Steroid hormone production
- Synthesis and storage of glycerides & glycogen
- Important role as a calcium store
How do proteins pass from the ER to Golgi body and then to other destinations into the cell?
Vesicles bud off the ER (are pinched off`) and are received by the Golgi body.
Vesicles are coated but this has to be discarded before the vesicle can fuse with the target component.
Once proteins are modified in the Golgi body, Plasma membrane and secreted proteins are delivered to the cell surface by the constitutive secretory pathway in non-polarised cells.
What is the role of SNAREs?
SNAREs aid in vesicles reaching the correct target.
SNARE - soluble N-ethylmaleimide-sensitive factor adaptor protein receptor
Two types
v-SNAREs : vesicle SNARES- found in the vesicle membrane.
t-SNARE: target SNARES found in the membrane of the target membrane
Describe the structure of the Golgi apparatus.
Golgi apparatus is composed of flattened discs – also called cisternae. A typical Golgi apparatus will normally consist of 5-6 cisternae.
The Golgi apparatus tends to lie near the nucleus
The cisternae communicate with the ER and cell membrane by use of vesicles and tubules.
The Golgi is a highly structured organelle. Vesicles released from the ER bind to the cis face and are then processed and leave from the trans face of the organelle.
What are the 3 primary functions of the Golgi apparatus?
Modification and packaging if secreted proteins.
Renewal and modification of the plasma membrane.
Delivery of material to other organelles.
