Advanced higher Biology key area 1.2 ( proteins)

Allosteric enzymes

Enzymes that change the conformation in response to the modulator

Alpha helix

Polypeptide chain coiled into a helix with hydrogen bonds to stabilise

Alternative RNA splicing

Removal of non-coding introns from primary mRNA transcript to leave only the coding exons ( several different combinations)

Beta pleated sheets

Polypeptide chains arranged in rows with the chain folding in parallel or anti-parallel arrangements

Conformations

Structural arrangements of the polypeptide within a protein; it can be altered by factors such as PH

Co-operativity

Changes in the binding of a target molecule to one subunit of a multiunit polypeptide changes the affinity of the other subunits for the target molecule

Disulfide bridge

A strong covalent bonds that stabilises the tertiary and quaternary structures of many proteins

Endoplasmic reticulum

A network of membrane tubes within the cytoplasm of a eukaryotic cell

Exon

A section of the DNA retained during splicing

Glycoprotein

A protein with a carbohydrate added by a post translational modification

Golgi apparatus

A series of flattened membrane discs that package proteins into membrane bound vesicles inside the cell before the vesicles are sent to their destination

Hydrogen bonds

Attractions between polar in which hydrogen is bound to a larger atom

Hydrolases

A class of enzyme that use water to break chemical bonds

Introns

A section of RNA usually removed during splicing

Ionic bonds

A type of bonding that involves electrostatic attraction between oppositely charged ions

Ligand

A substance that can bind to a protein; the protein has a shape complimentary to the ligand to allow binding

Lysome

A modified Golgi vesicle containing hydrolytic enzymes

Modulators

These bind to a secondary site on an enzyme to alter its conformation; positive modulators activate enzymes and negative modulators deactivate

Monomers

A mollecule that can bind chemically to other monomers to form polymer

Non-coding RNA gene

A gene that codes for RNAs other than messenger RNA , so do not encode protein

Phospholipid

A component of cell membranes

Post translational modification

Adittion of different chemicals groups to, or modification of, a protein to alllow a particular function

Prosthetic group

A non-protein groups unit tightly bound to a protein necessary for its function

Protein kinases

Catalyse the transfer of a phosphate from a donor mollecule

Protein Phosphatases

An enzyme that removes a phosphate group from its substrate

Primary structure

Sequence in which amino acids are found joined by peptide bonds 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 group

The arrangement of multiple folded polypeptide units folded together

Proteolytic cleavage

A major form of post translational modification; it occurs when a protease cleaves one or more bonds in a target proteins to activate, inhibit, or destroy

Proteome

The entire set of proteins expressed by a genome ( larger than the genome)

R-groups

Side groups that allow different bonding between amino acids and give them their wide range of functions

Basic R-group

Contains an amine functional group, producing a basic solution

Acidic R-group

Contains an acid in functional group and produces an acidic solution

Polar r-group

Group that prefers to exist in a watery environment

Hydrophobic r-group

Composed mostly of Hydrogen and carbon, and then to be repelled from water

Rough endoplasmic reticulum

Organelle made up of membranes with ribosomes attached

Signal sequence

A short sequence of amino acids at one end of the poly peptide that determines its location within the cell

Smooth endoplasmic reticulum

A membrous organelle found is most euakrotyic cells; its main function are synthesis of lipids and steroid hormones

Turns

Secondary structures that reverses the direction of the poly peptide chain

Vesicles

Small membrane bound compartments filled with liquid