The proteome Flashcards
what is the proteome?
The proteome is the entire set of proteins expressed by a genome
Why is the proteome larger than the number of genes?
(particularly in eukaryotes)
more than one protein can be produced from a single gene as a result of alternative RNA splicing
Are all genes expressed as proteins?
Not all genes are expressed as proteins in a particular cell type
What changes the proteins expressed by a given cell type?
The set of proteins expressed by a given cell type can vary over time and under different conditions
What do eukaryotic internal membranes do?
Eukaryotic cells have a system of internal membranes, which increases the total area of membrane
what does the endoplasmic reticulum (RER) form?
The endoplasmic reticulum (ER) forms a network of membrane tubules continuous with the nuclear membrane
What is the golgi apparatus?
The Golgi apparatus is a series of flattened membrane discs
What are lysosomes and what do they do?
Lysosomes are membrane-bound organelles containing a variety of hydrolases that digest
proteins, lipids, nucleic acids and carbohydrates
What do vesicles do?
Vesicles transport materials between membrane compartments
where are lipids and most proteins synthesized at some stage?
Lipids and most proteins are synthesised in the ER at some point.
Where are lipids synthesised?
Lipids are synthesised in the smooth endoplasmic reticulum (SER) and inserted into its membrane
Where do all proteins begin being synthesised?
The synthesis of all proteins begins in cytosolic ribosomes.
Where are cytosolic proteins completed?
The synthesis of cytosolic proteins is completed in the cytosolic ribosomes, and these proteins remain in the cytosol
What do transmembrane proteins do?
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 inserted into the membrane of the
ER
What happens to proteins in 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
The addition of carbohydrate groups is the major modification
Vesicles that leave the Golgi apparatus take proteins to the plasma membrane and lysosomes
Vesicles move along microtubules to other membranes and fuse with them within the cell
