Unit 1 Cells and Proteins: Key Area 2 - Protiens (Proteomics, Synthesis and Transport) Flashcards
What is genomics?
The study of the genome.
What is the genome?
The genome is the total genetic material in a cell.
What is the proteome?
The entire set of proteins expressed by a genome.
Is the proteome larger than the genome?
Yes, especially in eukaryotes.
Why is the proteome larger than genome?
The proteome is larger because more than one protein can be produced from a single gene as a result of alternative RNA splicing..
What are not always expressed as proteins in a cell?
Genes.
What are genes that do not code for proteins called?
Non-coding RNA genes.
What are examples of non-coding RNA genes?
Those that are transcribed to produce: tRNA, rRNA and RNA molecules that do not control the expression of other genes.
What factors and conditions affect the set of proteins expressed by a given cell type?
The metabolic activity of the cell, cellular stress, the response to signalling molecules and diseased v healthy cells.
What do eukaryotic cells have that increase the total area of membrane?
Eukaryotic cells have a system of internal membranes, which increases the total area of membrane.
Why do cells need membrane?
They increase the surface area of cells so the cell can carry out vital functions.
What does the Endoplasmic Reticulum (ER) do?
The endoplasmic reticulum (ER) forms a network of membrane tubules continuous with the nuclear membrane.
What are the two types of Endoplasmic Reticulum (ER)?
The Rough Endoplasmic Reticulum (RER)
And Smooth Endoplasmic Reticulum (SER).
What is the difference between the RER and SER?
The RER has ribosomes on its cytoplasmic face whereas the SER lacks ribosomes.
What is the Golgi Apparatus?
The Golgi apparatus is a series of flattened membrane discs.
What are Lysosomes?
Lysosomes are membrane-bound organelles containing a variety of hydrolases that digest proteins, lipids, nucleic acids and carbohydrates.
What function do Vesicles carry out?
Vesicles transport materials between membrane compartments.
What is the structure of membranes made up of?
Lipids and Proteins.
Where are lipids and proteins of the membrane structure synthesised?
In the SER.
What is the function of the SER?
To synthesise lipids and insert them, into there membrane.
Where does the synthesis of all proteins begin?
In cytosolic ribosomes where cytosomes are not attached to the ER.
What is protein synthesis, site of completion dependent on?
The type of protein being synthesised.
Where is the synthesis of cytosolic proteins completed and where do they go afterwards?
In cytosolic ribosomes and they 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.
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 happens after docking of a ribosome with ER to form RER?
Translation continues after docking and the protein is inserted into the membrane of the ER.
Where does synthesis start, finish and where does the product go for the product - Lipids?
Synthesis start in the SER and ends in the SER. The product goes to the SER membrane.
Where does synthesis start, finish and where does the product go for the product - Cytosolic proteins?
Synthesis start in the cytosolic ribosome and ends in the cytosolic ribosome. The product goes to the Cytosol.
Where does synthesis start, finish and where does the product go for the product - Transmembrane Proteins?
Synthesis start in the cytosolic ribosome and ends in the RER . The product goes to the RER Membrane.
Once synthesised at the ER, where can proteins go to?
They can move around the cell to wherever it is needed.
Once proteins are in the ER how are they transported?
Once the proteins are in the ER, they are transported by vesicles that bud off from the ER and fuse with the Golgi apparatus.
How do molecules move through the Golgi apparatus?
Molecules move through the Golgi discs in vesicles that bud off from one disc and fuse to the next disc in the stack.
What happens as proteins move through the Golgi apparatus?
As proteins move through the Golgi apparatus they undergo post-translational modification.
What happens to the proteins during post-translational modification in the Golgi apparatus?
The polypeptide chains have carbohydrates or phosphates added to them or are cleaved (cut) to make them an active protein.
What catalyses the addition of various sugars in multiple steps to form carbohydrates?
Enzymes.
Is the addition of carbohydrates to the protein a minor modification?
No, this is a major modification.
Where do vesicles that leave the Golgi apparatus take proteins to?
Vesicles that leave the Golgi apparatus take proteins to the plasma membrane and lysosomes which has a membrane.
What do vesicles move along?
Vesicles move along microtubules to other membranes and fuse with them within the cell.
What are microtubules?
Structure that make up the cell cytoskeleton and offer support and a means of transport.
What are the 5 different type of proteins?
S - Structural H- HormoneS A - Antibodies R - Receptors E - Enzymes
What happens to secreted proteins?
Secreted proteins are translated in ribosomes on the RER and enter its lumen. (Extra) They bud off the RER in a vesicle and go to the Golgi Apparatus.
What happens to the Secreted proteins that are translated and enter the lumen?
They move through the Golgi Apparatus and are packaged into secretory vesicles. These vesicles move to and fuse with the plasma membrane, releasing the protein out of the cell.
What are many secreted proteins synthesised as and what do they require to happen?
Many secreted proteins are synthesised as inactive precursors and require proteolytic cleavage to produce active proteins.
What is proteolytic cleavage?
A type of post-translational modification where the polypeptide is cut out.
What is an example of secreted proteins that require proteolytic cleavage to become active?
Digestive enzymes.
