1.2 - The Proteome Flashcards
Unit One
Proteome definition
The entire set of proteins expressed by a genome
Size comparison of proteome and gene number
The proteome is drastically larger than the number of genes in the genome, particularly in eukaryotes, because more than one protein can be produced from each gene due to alternative splicing, and post translational modifications.
What do non-coding RNA genes produce
tRNA, rRNA and RNA molecules which control expression of other genes
Are all genes expressed as proteins
No, some are expressed as RNA molecules
Full name of SER
Smooth Endoplasmic Reticulum
Full name of RER
Rough Endoplasmic Reticulum
What is the purpose of the intracellular membrane
To increase the surface area to volume ratio, to allow for vital cell functions to take place
What is the difference between the RER and the SER
The rough endoplasmic reticulum has ribosomes and produces proteins while the smooth endoplasmic reticulum does not have proteins and produces lipids (fats)
Function of the endoplasmic reticulum
The ER creates a network of membrane tubules continuous with the nuclear membrane to produce lipids and proteins
Golgi apparatus
The cell organelle which receives proteins and lipids from the ER. Consisting of a series of flattened discs to process, carry outpost translational modification and send those modified proteins and lipids off to their destination
Lysosome definition
Membrane bound organelles containing hydrolases that digest proteins, lipids, carbohydrates and nucleic acids
Hydrolase definition
Enzymes that use water to break down substrates such as proteins, fats, nucleic acids and carbohydrates
What is the name of genes that don’t code for proteins
Non-coding RNA genes
Factors affecting proteins expressed in a cell
Metabolic activity, cellular stress, response to signalling molecules or disease
Vesicle definition
Cell organelles which transport materials between membrane compartments
What are intracellular membranes
They are membranes inside a cell which increase the cell membrane surface area to ratio
Lysosome pH
Acidic to allow for optimum enzyme activity
What is cytosol
Cytosol is part of the cytoplasm where the new cell organelles are suspended
Process of producing a cytosolic protein
- mRNA will leave the nucleus and travel to a ribosome in the cytosol
- the ribosome will remain in the cytosol
- a polypeptide chain will then be produced by the ribosome
- this will then fold into shape and become a protein will remain in the cytosol
Process of producing a transmembrane protein
- an mRNA strand travels from the nucleus to the cytosolic ribosome
- the cytosolic ribosome produces a polypeptide chain containing a signal sequence
- the cytosolic ribosome then travels to the endoplasmic reticulum and docks with it forming the RER
- translation then continues at the RER and is then packaged into a vesicle to be transported to the Golgi apparatus
- the Golgi apparatus then processes and carries out post translational modification
- then the transmembrane protein is sent out to its destination
How do proteins travel away from the rough endoplasmic reticulum
They use vesicles which bud off the endoplasmic reticulum and fuse to the Golgi apparatus
signal sequence definition
The sequence of amino acids that informs the ribosome that it needs to dock with the endoplasmic reticulum
Destination of cytosolic ribosomes
Nucleus, mitochondria, chloroplasts
Destination of transmembrane proteins
Plasma membranes, secretory vesicles, lysosomes