The Synthesis And Transpirt Of Proteins Flashcards
What do eukaryotic cells have
A system of internal membranes which increases the total area of the membrane
Because of their size what do eukaryotes have
Relatively small surface area to volume ratio
Describe the plasma membrane of eukaryotic cells
To small to carry out all the vital functions carried out be membranes
LEARN HOW TO NAME ALL THE PARTS IF EUKARYOTIC CELL
What does the endoplastic reticulum do
Forms a network of membrane tubules continuous with the nucleus membrane
What is the Golgi apparatus
A series of flattened membrane discs
What are lysosomes
Membrane bound organelles containing a variety of hydrolyses that digest proteins, lipids, nucleic acids and carbohydrates
What do vesicles do
Transport materials between membrane compartments
LEARN OTHER MEMBRANE DIAGRAM !,!
What are synthesised in the endoplasmic reticulum
Lipids and proteins
What does a rough ER have and a smooth er
Ribosomes on its cytosolic face while smooth lack ribosomes
Where are lipids synthesised
In the smooth endoplasmic reticulum and inserted into its membrane
Where is the synthesis of proteins
The synthesis of all proteins begins in the cytisolic ribosomes
Where are cytsolic proteins synthesised
In the cytosolic ribosomes and remain in the cytosol
What do transmembrane proteins do
Carry a signal sequence which halts translation and directs the ribosome synthesising the protein to the dock with the ER forming RER
What is a signal sequence
A short stretch of amino acids at one end of the polypeptide that determines the eventual location of a protein in a cell
What continuous after docking
Translation and the protein is inserted into the membrane of the ER
LEARN HOW TONLABEL SYNTHESIS RER DIAGRAM
What are the stages of synthesis by RER
1, proteins are synthesised by ribosomes in the cytoplasm
2, a signal protein from the membrane binds to the ribosome and stop’s translation
3, The signal protein binds to the receptor directs the ribosome to attach to the endoplasmic reticulum forming RER
4, translation restarts and the proteins is now inserted into membrane of the ER
5, once translation is finished the ribosome detaches
What happens once the proteins are in the ER
They are transported by vesicles that bud of from the ER and fuse with the Golgi apparatus
What happens as proteins moves through the Golgi apparatus
They undergo post translational modification, the addition of the carbohydrate is the major modification
LEARN HIW TO LABEL GOLGI DIAGRAM
Where do molecules move through in the Golgi apparatus
Golgi discs in the vesicles
What do enzymes to in the Golgi apparatus
Catalyse the addition of various sugars in multiple steps to form carbohydrates
What do vesicles that leave the Golgi apparatus do
Take proteins to the plasma membrane and lysosome
What do vesicles do
Move along microtubules to other membranes and fuse with them within the cell
Where are secreted proteins translated
In the ribosomes on the RERand enter it’s lumen
What are examples of secreted proteins
Peptide hormones
Digestive enzymes
LEARN HOW TO LABEL SECRETORY PATHWAY
What do proteins do in the secretory pathway
Move through Golgi apparatus and are packaged into secretory vesicles
What do vesicles do I’m the secretory pathway
Move and fuse with the plasma membrane releasing proteins out of the cell
What happens to many secreted proteins
Synthesised as inactive precursors and require proteolytic cleavage to produce active proteins
What is proteolytic cleavage
Type of post translational modification
Name examples of secreted proteins that require proteolytic cleavage
Digestive enzymes and insulin
