Unit 1 Key Area 2 Flashcards
What is the proteome
The entire set of genes expressed by the genome
Why is the proteome larger than the genes
Because more than one protein can be produced from one single gene as a result of the alternative rna splicing
What are genes called that do not code for proteins
Non coding RNA genes
What do non coding rna genes include
Those that are transcribed to produce tRNA, rRNA & RNA molecules that control the expression of other genes
The set of proteins can vary over time and under different conditions. What are these conditions
Metabolic activity of the cell
Diseased vs healthy cells
Cellular stress
The response to signalling molecules
What in eukaryotic cells increases the total area of membrane
System of internal membrane
do eukaryotes have a small or large SA:Volume ratio
RELATIVELY SMALL
What is a con of having a small plasma membrane
it hs too small for carrying out vital functions carried out by membranes
What is the endoplasmic recticulum
a network of membrane tubules continuous with the nuclear membrane
what is the golgi apparatus
a series of flattened membrane discs
what is a lysosome
membrane bound organelles cintaining a variety of hydrolases
what do hydrolases digest
Lipids, nucleic acids and carbs
what is a vesicle
it transports materials between membrane compartments
where are lipids and proteins synthesised
the endoplasmic reticulum
what is the Rough Endoplasmic reticulum
has ribosomes on its cytosolic face while smooth er lacks ribosomes
what happens with the lipids in the SER
inserted into its membrane
where does the synthesis of all proteins begin
the cytosolic ribosomes
where is the synthesis of proteins completed
the cytosolic ribosomes
where do the proteins remain after completion of synthesis
in the cytosol
what do transmembrane proteins carry
a signal sequence
what does a signal sequence do
halts translation and directs the ribosome synthesising the protein to dock with the ER
what does the docking of ribsomes form
the 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
when does translation occur
continues after docking and the protein is inserted into the membrane of the ER
What happens when the proteins are in the ER
they are transported by vesicles that bud off from the ER and fuse the golgi apparatus
what happens in the golgi apparatus
the proteins move through the GA and they undergo Post translational modification
what is the process for going through the golgi apparatus
molecules move through the golgi disc in vesicles that bud off from one disc and fuse to the next one in the stack.
what do enzymes do in the golgi
catalyse the addition of various sugars in multiple steps to form the carbohydrates
what is a MAJOR modification
the addition of carbohydrate groups
what happens after the post translational modifications
the vesicles leave the golgi apparatus and take proteins to the plasma membrane and lysosomes
where do vesicles also move to
move along microtubules to other membranes and fuse with them within the cell
What is are examples of secreted proteins
peptide hormones and digestive enzymes
where do secreted proteins begin translation
in ribosomes on the rer by entering its lumen
what is the process of the secratory pathway
enter the rer lumen then move through the golgi apparatus (the normal protein synthesis occurs) the PTM occurs they are then packaged into secretory vesicles and the vesicles move to and fuse with the plasma membrane releasing the proteins out of the cell or move along microtubules
what are many secreted proteins synthesised as?
inactive presursors
what do inactive precursors require
proteolytic cleavage to produce active proteins
what is proteolytic cleavage
another type of PTM
why are digestive enzymes secreted proteins
if they were active within the cell it would be lethal for the cell and they require proteolytic cleavage to become active and carry out its function
What do amino acids differ in
the R group present
What do R groups vary in
size, shape, charge, hydrogen bonding capacity and chemical reactivity
what are the r group classified as?
basic (+) acidic (-) polar and hydrophobic
what does a diversity allow proteins to do
carry out a range of functionsw
what is the primary function
the sequence in which the amino acids are synthesised into the polypeptide
WHat does the secondary structure involve
hydrogen bonding along the backbone allowing the alpha helices, parallel or anti- parallell beta pleated sheets or turns to form
what does folding of the polypeptide form
the tertiary structure
how is the tertiary strucure stablised
with interactions between the r groups
what is the quaternary structure
exists in proteins with twoor more connected polypeptide subunits
what does the QS describe
the spatial arrangement of subunits
what are disulfide bridges
covalent bonds between r groups containing sulfur
ilhhd
what are examples of the interactions between the r groups
Ionic bonds
London Dispersion forces
Hydrogen bonds
hydrophobic interactions
Disulfide bridges
what does a decrease in pH or increase in temperature do to the affinity of haemoglobin to oxygen
decrease affinity of haemoglobin for oxygen ∴ a reduced binding and this then causes the promotion of increases oxygen delivery to tissue
what is a prosthetic group
a non-protein unit tightly bound to a protein essential for its function
what is the ability of haemoglobin binding to O2 dependent on
the non-protein haem group
