1.2b - The Synthesis and Transport of Proteins Flashcards
Eukaryotic cells have a system of internal membranes which…
increases the total area of membrane
Because of their size, eukaryotes have a relatively small…
surface area to volume ratio
The plasma membrane of eukaryotic cells is too small an area to…
carry out all the vital functions carried out by membranes
The endoplasmic reticulum (ER) forms a…
network of membrane tubules continuous with the nuclear membrane
The Golgi apparatus is…
a series of flattened membrane discs
Lysosomes are…
membrane-bound organelles
Lysosomes contain…
a variety of hydrolases that digest proteins, lipids, nucleic acids and carbohydrates
Vesicles transport materials between…
membrane compartments
Lipids and proteins are synthesised in the…
ER
The Rough ER (RER) has…
ribosomes on its cytosolic face
The Smooth (SER)…
lacks ribosomes
Lipids are synthesised in the SER and inserted…
into its membrane
The synthesis of all proteins begins in…
cytosolic ribosomes
The synthesis of cytosolic proteins is completed in…
the cytosolic ribosomes
Cytosolic proteins remain in the…
cytosol
How is RER formed?
transmembrane proteins carry a signal sequence, which halts translation and directs the ribosome synthesising the protein to the dock with the ER, forming RER
Translation continues after docking, and the protein is…
inserted into the membrane of the ER
Once the proteins are in the ER, they are…
transported by vesicles that bud off from the ER and fuse with the Golgi apparatus
As proteins move through the Golgi apparatus…
they undergo post-translational modification
Molecules move through the Golgi discs in…
vesicles that bud off from one disc and fuse to the next one in the stack
Enzymes catalyse the addition of various sugars in multiple steps to…
form the carbohydrates
Vesicles that leave the Golgi apparatus take proteins…
to the plasma membrane and
lysosomes
Vesicles move along the microtubules and…
fuse with them within the cell
Secreted proteins are…
translated in ribosomes on the RER and enter its lumen
2 examples of secreted proteins
peptide hormones and digestive enzymes
The proteins move through the Golgi apparatus and are then…
packaged into secretory vesicles
Many secreted proteins are synthesised as…
inactive precursors and require proteolytic cleavage to produce active proteins
Proteolytic cleavage is a type of…
post-translation modification
Digestive enzymes are one example of…
secreted proteins that require proteolytic cleavage to become active
