Biomolecules Biomolecules are molecules produced by living organisms or are compounds that occur naturally in plants and animals. They could be large macromolecules or smaller molecules such as primary or secondary metabolites Macromolecules Proteins ucleic acids Polysaccharides Lipids Small Molecules Terpenoids Steroids Sugar Derivatives i Amino Acids and Peptides Alkaloids
ucleic Acids ucleic acids (DA and A) are unquestionably the top levell molecules l because they store our genetic information. They are polymers of nucleotides, which themselves are made of three parts a heterocyclic base, a sugar, and a phosphate ester. ucleotide The base along with the sugar forms a nucleoside, which combined with the phosphate group forms the nucleotide Phosphates are key compounds in nature because they form useful stable linkages between molecules and can also be built up into reactive molecules by simply multiplying l i the number of phosphate h residues. The most important tof these nucleotides is also one of the most important molecules in nature Adenosine triphosphate or ATP.
The Components of ucleic Acids In nucleic li acids there are only five bases, two sugars, and one phosphate h group possible. The bases are monocyclic pyrimidines or bicyclic purines and are all aromatic. The two sugars are ribose (A) and 2-deoxy ribose (DA). Bases Sugar 2 adenine guanine 2 ribose (A) 2 uracil (A) thymine (DA) cytosine 2-deoxyribose (DA)
The Double elix Structure Each polymeric strand of DA coils up into a helix and is bonded to another strand by hydrogen bonds between the bases. Each base pairs up specifically with another base: adenine with thymine (A T) and guanine with cytosine (G C) P P P 5' 3' 2' A 2 A 2 T Double elix adenine guanine thymine cytosine Each purine (A or G) is bonded specifically to one pyrimidine (T or C) by two or by three hydrogen bonds. The hydrogen bonds are of two kinds: one links an amine to a carbonyl group and one links an amine to an imine.
Modified ucleosides and Bases
Proteins Proteins are made of amino acids and are formed in livingi organisms based on the information contained in DA. -TAC- DA Triplet A Synthesis -AUG- A Triplet Instructiontobegin Protein Synthesis Polyamides Protein Synthesis 2 C Methionine S
Structure of Proteins Amino acids are the basic units of proteins and are linked together th through h amide bonds. 2 L-amino acid The -groups can be alkyl, aromatic, alcoholic or phenolic, thiol or thioether, basic groups like amine or guanidine and carboxylic acids. In proteins these individual groups act together to perform various functions. The linear chain of amino acids (primary structure), folds itself through various interactions to give secondary, and tertiary structures. In some proteins, two or more tertiary structured protein subunits join together to give quaternary structures. The function of a protein is highly affected by the three dimensional structure it can adopt. The function of certain proteins is to provide structural stability.
Glutathione A functional tripeptide Smaller chains of amino acids, joined together th by amide bonds are called peptides. C 2 S glutathione - S C Glutathione is a tripeptide formed from glutamic acid, cysteine and glycine. The middle amino acid is the vital one for the function cysteine with a free S group. Thiols are easily oxidized to disulfides and glutathione sacrifices itself if it meets an oxidizing agent. Later, the oxidized form of glutathione is reduced back to the thiol. 2 2 S S S S S S Gl t thi l t l hil d t ith t i d th t t th Glutathione also act as a nucleophile and react with toxic compounds that enter the body to make them harmless substances
Lipids Lipids (fats) are important components of cell membranes. They are essential to the function of membranes as selective barriers to the movement of molecules. The most common types of lipids are esters of glycerol. Glycerol is just propane-1,2,3- triol ilbut it has interestingi stereochemistry. It is not chiral as it has a plane of symmetry, but the two primary groups are enantiotopic. If one of them is changed by esterification, for example the molecule becomes chiral. atural glycerol phosphate is suchanester e and it is optically active. Typical lipids found in food are triesters of glycerol with various fatty acids, depending on the source. For example: live oil is the triester of glycerol with oleic acid a 18 carbon carboxylic acid with a cisdouble bond between the 9 th and 10 th carbon atoms.
Sugars Sugars are the building blocks of carbohydrates. Their functions include, Provision of energy Construction of cell wall ecognition of proteins Sugars normally exist in cyclic forms. Glyceraldehyde is the simplest aldehyde sugar or aldose and dihydroxyacetone is the simplest keto-sugar or ketose. C glyceraldehyde dihydroxyacetone
Glycosides