U1 - Synthesis And Transport Of Proteins Flashcards
What do eukaryotic cells have that increase the total area of the membrane
A system of internal membranes as the plasma membrane is too small to carry out all the vital functions carried out by membranes
What is the ER
The endoplasmic reticulum forms a network of membrane tubules continuous with the nuclear membrane
What is the Golgi apparatus
Is a series of flattened membrane discs
Lysosomes
Membrane bound organelles containing a variety of hydrolysed that digest proteins, lipids, nucleus acids and carbohydrates
What do vesicles do?
Transport materials between membrane compartments
Where are the lipids and proteins synthesised
They are synthesised in the ER. Lipids are synthesised in the SER and inserted into its membrane
Where does the synthesis of proteins begin?
The synthesis of proteins begins in the cytosolic membrane (cytoplasm). The synthesis of cytosolic proteins is completed in the cytosolic
What is a signal sequence and what carry’s it
A signal sequence is a short stretch of amino acids at one end of a polypeptide that determines the eventual location of a protein in a cell. It is arrived by a transmembrane protein.
Summarise protein synthesis
Transmembrane proteins carry a signal sequence, which halts translation and directs the ribosome synthesising the protein to dock with the ER, forming RER. Translation continues after docking and the protein is insterted into the membrane of the ER
Summarise the movement of proteins between membranes
Once the proteins are in the ER they are transported by vesicles that bud off from the ER and fuse with the Golgi apparatus
What is the role of vesicles in protein synthesis
Transport the protein from the ER to fuse with the Golgi apparatus. They then take the proteins to the plasma membrane and vesicles
What happens to proteins as they move through the Golgi apparatus
They undergo post-transnational modification where a carbohydrate is added.
How do vesicles move
Vesicles move along microtubules to fuse with other membrane compartments
How are carbohydrates added to the proteins during modification
Enzymes catalyse the addition of various sugars in multiple steps to form the carbohydrates
Where are secreted proteins translates
Secreted proteins are translated in ribosomes on the RER and enter its lumen.
