Cells And Proteins- Proteins Flashcards
What is the proteome?
The entire set of proteins expressed by a genome
Not all genes are expressed as proteins…
In a particular cell type
What can happen to the set it proteins expressed by a given cell type?
Can vary over time and under different conditions
Describe lysosomes
Membrane bound organelles containing a variety of hydrolysed that digest proteins, lipids, nucleus acids and carbon
What is the role of vesicles?
Transport materials between membrane compartments
Where are lipids synthesised?
In the smooth ER and inserted into its membrane
What happens in cytosolic ribosomes
The synthesis of all proteins
What happens to cytosolic proteins?
Synthesis is completed in the cytosolic ribosomes, and these proteins remain in the cytosol
How is the RER formed?
Transmembrane proteins carry a signal sequence, which halts translation and directs the ribosome synthesising the protein to dock with the ER, forming the RER
What happens after the ribosome synthesising the protein docks?
The protein is inserted into the membrane of the ER
What is the process if movement of proteins between membranes
1) Once that proteins are int he ER they are transported by vesicles that bud off from the ER and fuse with the Golgi apparatus.
2) As proteins move through the Golgi apparatus they undergo post translational modification.
3) the addition of carbohydrate groups is the major modification.
4) vesicles that leave the Golgi apparatus take proteins to the plasma membrane and lysosomes.
5) vesicles move along microtubules to other membranes and fuse with them within tue cell
Describe the secretory pathway
1) secreted proteins are translated in ribosomes on the RER and enter its lumen.
2) the proteins move through the Golgi apparatus and are then packed into secretory vesicles.
3) these vesicles move to and fuse with the plasma membrane, releasing the proteins out of the cell.
4) many secreted proteins are synthesised as inactive precursors and require proteolytic cleavage to produce active proteins
What do amino acids determine?
Protein structure
The wide range of functions carried out by protein’s results from what?
The diversity of R groups
What happens to R groups not involved in protein folding?
Can allow binding to ligand
What does the change in conformation lead to?
A functional changes in the protein
What do allosteric proteins with multiple subunits show?
Co-operativity in binding, in which changes in the binding of one subunit alters the affinity of the reaming subunits
What do protein kinases do?
Catalyse the transfer of a phosphorus group to other proteins
What do protein phosphatases do?
Catalyse the reverse reaction
How are many cellular proteins, such as enzymes and receptors, regulated?
Phosphorylation
