PROTEINSBy: 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.

AMINO 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)

AMINO ACIDS

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.

MAIN 20 TYPES OF AMINO ACIDS

Polar Non-Polar Acidic (Polar)

Basic (Polar)

Serine Glycine Aspartic Acid Lysine

Threonine Alanine Glutamic Acid Arginine

Asparagine Valine Histidine

Glutamine Leucine

Cysteine Isoleucine

Tyrosine Proline

Methionine

Phenylalanine

Tryptophan

AMINE

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.

CARBOXYLIC ACID 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 GROUP

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.

AMINO ACID

PEPTIDE BOND

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

STRUCTURES OF PROTEINS 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.

PRIMARY STRUCTURE

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.

SECONDARY STRUCTURE

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.

SECONDARY STRUCTURE

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 4th amino acid

Beta Pleated Sheet: formed by 2+ parallel regions that form bonds holding them together.

TERTIARY STRUCTURE

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.

QUATERNARY STRUCTURE

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.