P ROTEINS By: Jenny, Susana, Jessica, Ruian, Michelle
FUNCTIONS Building blocks of living things. Regulation of enzymes and hormones Growth Enzyme catalyst used to transport and store molecules Carry out cell functions Responsible for growth and reparations of body cells/tissues Ex: Help with oxygen transport, blood clotting, fix broken bones etc.
A MINO ACIDS Amino acids are the smallest units that make up proteins. They are molecules composed of 2 functional groups: Amino group – made from nitrogen bonded with 2 hydrogens Carboxyl group – 1 carbon single-bonded to O-H, double bonded to oxygen Amino acids differ depending on their R group (remainder of molecule excluding the amino and carboxyl groups)
A MINO A CIDS Amino acids help determine the properties of a protein 20 different amino acids; about 20 different types of R groups commonly found in proteins. The amine and carboxyl group, along with the alpha carbon, form the base of the amino acid which is found in all of the 20 amino acids relevant to biochemistry.
M AIN 20 TYPES OF A MINO A CIDS PolarNon-PolarAcidic (Polar)Basic (Polar) SerineGlycineAspartic AcidLysine ThreonineAlanineGlutamic AcidArginine AsparagineValineHistidine GlutamineLeucine CysteineIsoleucine TyrosineProline Methionine Phenylalanine Tryptophan
A MINE Consists of two hydrogen atom bonded to a nitrogen atom. Is an organic functional group, represented by the chemical symbol (NH2). Is connected to the amino acid by the alpha/chiral carbon.
C ARBOXYLIC A CID Is represented by the chemical symbol (COOH). Consists of two oxygen atoms bonded to a carbon One single bonded One double bonded A hydrogen atom singly bonded to an oxygen atom The carbon atom in the carboxyl group is also bonded to the alpha/chiral carbon.
R G ROUP Represents the side chain which distinguishes each amino acid from another. Can be a variety of arrangements of organic atoms extending from the alpha carbon. The R group gives each amino acid its distinct characteristics, and amino acids are frequently represented by their side chains.
A MINO A CID
P EPTIDE B OND A covalent bond between 2 amino acids Creates polymers Caused by a dehydration reaction Bonds when the carboxyl group is adjacent to the amino group
S TRUCTURES OF P ROTEINS Different proteins each have their own unique 3D shape and their own different functions They are all made up the same set of 20 amino acids Are one or more polypeptide chains folded, coiled or twisted to make a single, uniquely shape molecule. The order of amino acids and the way proteins are shaped determines the way proteins function Slight changes could the change the function or render the protein non-functional. There are 3 main levels of protein structure + a fourth level when 2 or more polypeptide chains in a single protein molecule.
P RIMARY S TRUCTURE Defined as the way that amino acids are specifically sequenced in the polypeptide chains. Determined by inherited genetic info Slight differences can affect the form/shape and the functionality of the protein.
S ECONDARY S TRUCTURE Determined by the coils and folds formed by the shape. The coils and folds are determined mainly by the order of amino acids; where the weak hydrogen bonds are in the chain. The hydrogens have a weak positive charge and create hydrogen bonds with the slightly negatively charged nitrogen or oxygen atoms. Hydrogen bonds are very weak, but hold the structure of the polypeptide chain together through sheer numbers.
S ECONDARY S TRUCTURE There are two main types of coils or folds that are formed by these weak hydrogen bonds. Alpha Helix: formed by hydrogen bonds made between every 4 th amino acid Beta Pleated Sheet: formed by 2+ parallel regions that form bonds holding them together.
T ERTIARY S TRUCTURE Tertiary structure is the overall 3D shape of the protein molecule formed by R groups and the different ways that it folds from the secondary structure. Includes the irregular folds/coils resulting from non-covalent reactions of the R groups.
Q UATERNARY S TRUCTURE A fourth level is present when 2+ polypeptide chains combine to form a single functioning molecule. Like the tertiary structure, it is the overall 3D shape of the two combined polypeptides that create the single molecule.