Advanced Higher Biology Prelim Revision Flashcards
what is SDS- PAGE
separation of proteins by size alone
how does SDS-PAGE separate proteins
by giving all molecules an equally negative charge and denaturing them
what is western blotting
this is an analytical technique used after SDS-PAGE
what is involved in western blotting
the gel is run and then the separated proteins are transferred onto a solid medium.
how are proteins identified using western blotting
using specific antibodies that have reporter enzymes attached
what is bright filed microscopy
used to observer:
- whole organisms
- parts of organisms
- thin sections of dissected tissue
- individual cells
what is a haemocytometer
a graduated microscope slide that can be used to estimate cell numbers in a liquid culture
what must be present in a cell culture
growth factors and nutrients
what are growth factors
protein which promote cell growth or proliferation
what is a colorimeter
used to measure the concentration of a pigment in a solution
what is the proteome
the number of proteins expressed by a genome
why is the number of proteins expressed higher than the number of genes expressed
due to alternative RNA splicing producing multiple proteins expressed by a single gene
where are all protein synthesised
in the cystolic ribosome
where are transmembrane protein synthesis completed
not completed in the cystol instead they carry a signal sequence which halts translation and directs the ribosome to doc with the endoplasmic reticulum
what is the signal sequence on the transmembrane protein
short stretch of amino acids at the end of the polypeptide which determines the eventual location of the protein
Describe the movement of proteins between membranes
- proteins enter the membrane of the ER and are then 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-translation modifications
- molecules move through the Golgi discs in vesicles
- vesicles that leave the Golgi then take proteins to the plasma membrane
what are the post-translational modification in the Golgi
addition of a carbohydrate molecule
what is the quaternary structure
exists in proteins with several connected polypeptide subunits which are linked by bonds between the R -groups of the chain
what are the 4 main amino acid classes
acidic - COOH carboxylic acid
basic - NH2 amine group
polar - OH hydroxide group
hydrophobic - CH hydrocarbon
What is a peptide bond
joins two amino acids together to create a polypeptide chain
how is a polypeptide chain formed
a condensation reaction
what is a ligand
a substance which can bind to a protein
what happens when the ligand binds
there is a conformational change which causes a change in the function of the protein
what is a modulator
binds to the allosteric site of an enzyme altering the affinity of the active site for a substrate