FCELL- fate of newly synthesised proteins

Question 1

why do proteins need to be targeted to different locations

Answer 1

animal cells have different compartments and membrane bound organelles - each compartment carries out specific functions that need to be separated from other processes

proteins are specific to enhancing these specific processes

synthesised in the cytosol so need to go to the organ that needs it for function

Question 2

outline the concept of signal sequences

Answer 2

ER proteins / organelle-specific uptake-targeting sequence
each compartment of cell has a different signal sequence
each signal sequence has a specific receptor

nucleus -5’ AA which are found within the protein

Question 3

what are the cellular roles of the nucleus

Answer 3

double membrane - continuous with ER membrane

nuclear pore complex = proteins embedded in double membrane and cytosolic fibrils and nuclear basket

nuclear import- dependent on size - small molecules can diffuse in by free diffusion, larger ones need to be imported via active transport - require energy and specific receptors

T - antigen expression exclusive in nuclei

Question 4

what are the stages of the secretion of proteins

Answer 4

vesicle genesis
cargo loading 
concentration and processing
vesicle transport and targeting 
vesicle docking
calcium dependent vesicular fusion