1.2 proteins Flashcards
alternative RNA splicing
removal of non-coding inions form a primary mRNA transcript to leave only the coding axons; several different mature transcripts can be produced from a single primary trancript
ER (endoplasmic reticulum)
a network of membrane tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane
exon
section of RNA usually retained during splicing
glycoprotein
a protein with a carbohydrate added by post-translational modification
Golgi apparatus
a series of flattened membrane discs the package proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination
hydrolyses
a class of enzyme that use water to break chemical bonds
intron
a section of RNA usually removed during splicing
lysosome
a modified Golgi vesicle containing enzymes
non-coding RNA gene
a gene that codes for RNA’s other than messenger RNA, so they do not code for a protein
phospholipid
component of cell membrane
post-translational modification
addition of different chemical groups to, or modification of, a protein to allow for a particular function
proteolytic cleavage
a major form of post-translational modification; it occurs when a protein cleaves one or more bonds in a target protein to activate, inhibit or destroy the proteins activity
proteome
the entire set of proteins expressed by a genome; it is much larger than the genome
RER (rough endoplasmic reticulum)
organelle made up of membrane with ribosomes attached
signal sequence
a short stretch of amino acids at one end of the polypeptide that determines its eventual location in a cell
SER (smooth endoplasmic reticulum)
a membrane organelle found in most eukaryotic cells; its main function are to synthesis of lipids and proteins
vesicles
small membrane bound compartments filled with liquid
allosteric enzymes
enzymes that change conformation in response to a modulator
alpha helix
polypeptide chain coiled into a helix with hydrogen bonding occurring to maintain the arrangement
beta-pleated sheets
polypeptide chain arranged in rows with the chain folding in parallel or anti-parallel arrangements
conformation
structural arrangement of the polypeptide chains within a protein; it can be altered by factors such as pH and the binding of ligands and modulators
co-operativity
changes in binding of a target molecules to one subunit of a multiunit polypeptide changes the affinity of the other subunits for the target molecule
disulphide bridge
a strong covalent bond that stabilises the tertiary and quaternary structures of many proteins
hydrogen bonds
attractions between polar molecules in which hydrogen is bound to a larger atom, such as oxygen or nitrogen
ionic bonds
a type of chemical bonding that involves the electrostatic attraction between opposites charged ions
ligand
a substance that can bind to a protein; the protein has a complementary shape to the ligand to allow binding
London dispersion force
a temporary weak attraction between atoms and molecules
modulators
these bind to a secondary site on an enzyme to alter its conformation; positive modulators activate enzymes and negative modulators deactivate/inhibit them
monomer
a molecule that can bind chemically to other monomers to form a polymer
polymer
a macromolecule composed of many repeated subunits
prosthetic group
a non-protein unit tightly bound to a protein and necessary for its function
protein kinases
catalyse the transfer of a phosphate group from a donor molecule (usually ATP) to an acceptor
protein phosphatases
an enzyme that removes a phosphate group from its substrate
protein strucure
different levels of arrangement of polypeptides within a protein
primary structure
sequence in which amino acids are found within a protein
secondary structure
hydrogen bonding occurring within a polypeptide forming alpha helices or beta-pleated sheets
tertiary structure
bonding of many types occurring between the R groups of amino acids within a protein
quaternary structure
the arrangement of multiple folded polypeptides connected together
proteolytic cleavage
a major form of post-translation modification; it occurs when a protease cleaves one or more bonds in a target protein to activate, inhibit or destroy the proteins activity
R groups
side groups that allow different bonding between amino acids and give them their wide range of functions
hydrophobic group
composed mostly of carbon and hydrogen, and tend to be repelled from water
turns
secondary structure that reverses the direction of a polypeptide chain
Factors that effect protein activity
Metabolic activity
Cellular stress
Hormones
Disease
Cytosolic proteins include
Enzyme of glycolysis
Enzymes that attach amino acids to tRNA molecules for synthesis
Amino acid R groups
Basic
Acidic
Polar
Hydrophobic
Interactions between R groups can be
Hydrophobic
Ionic
Hydrogen
LDFs
Disulfide bridges
Interactions between the R groups can be altered by
Temperature and PH
What influences affinity
PH
temperature
