Biomolecules: carbohydrates and lipids

H O C N Few elements but many compounds In the complex world of living organisms, there are essentially 4 constituent elements: hydrogen oxygen carbon nitrogen H O C N Biomolecules: carbohydrates and lipids

Biological macromolecules Biological macromolecules can be divided into 4 families CARBOHYDRATES (or saccharides or sugars) LIPIDS (or fats) PROTEINS NUCLEIC ACIDS Biomolecules: carbohydrates and lipids / Biological macromolecules

Mean composition of an organism The ‘dry’ part of living organisms consists of of proteins and nucleic acids. Carbohydrates and lipids are used as a source of energy. Biomolecules: carbohydrates and lipids / Mean composition of an organism.

The cell Cell is an autonomous structure but it is in relationship with other cells and the outside world. Biomolecules: carbohydrates and lipids / The cell

Metabolism: the role of energy

Biochemical reactions involved in metabolism The metabolism The set of reactions that take place in cells and in the organism are known as “metabolism” (from the Greek metabolé meaning “change, modification”). Biochemical reactions involved in metabolism energetic status physiological role Biomolecules: carbohydrates and lipids / Metabolism: the role of energy

Endoergonic (require energy) Exoergonic (release energy) Metabolic maps Very complex sequences of biochemical reactions are described by metabolic maps. Reagents Products Direction of reactions (Energetic status) Precursors Metabolites Endoergonic (require energy) or Exoergonic (release energy) Biomolecules: carbohydrates and lipids / Metabolism: the role of energy

Reactions of metabolism Catabolism vs Anabolism Reactions of metabolism catabolism anabolism degrade the larger molecules with oxidation and are exoergonic construct large molecules us ing reduction and are endoergonic Biomolecules: carbohydrates and lipids / Matabolism: the role of energy

Carbohydrates: energy and support Carbohydrates, also known as saccharides or sugars, are composed of carbon, oxygen and hydrogen. Molecules to get energy from by breaking the chemical bonds with complex sets of reactions. The result is a stable system. They form the scaffolding support of plants. Biomolecules: carbohydrates and lipids / Carbohydrates: energy and support

Carbohydrates Carbohydrates can be divided into 3 broad groups: Monosaccharides Disaccharides Polysaccharides Biomolecules: carbohydrates and lipids / Catabolism vs Anabolism

Monosaccharides Contain 4, 5 or 6 carbon atoms but the most common in nature are pentoses or hexoses Depending upon they contain the aldehyde or the ketone functional group the monosaccharides are divided into: ketoses aldoses Biomolecules: carbohydrates and lipids / Monosaccharides

The Dextro configuration Monosaccharides consist of D or L configurations by how the hydroxyl group linked to carbon is arranged. Biomolecules: carbohydrates and lipids / The Dextro configuration

The cyclical structure Monosaccharides may also occur with a closed structure: cyclical. An example is glucose. Biomolecules: carbohydrates and lipids / The cyclical structure

The energy of life Sources of energy for all living things are Glucose and Fructose (ketohexose) found in fruit and honey together with ribose and deoxyribose, which are constituents of nucleic acids. Biomolecules: carbohydrates and lipids / The energy of life

Carbohydrates derived from the condensation Oligosaccharides and Disaccharides Carbohydrates derived from the condensation of several monosaccharide molecules (from two to five), with loss of one or more molecules of water and the formation of a glycosidic bond. Disaccharides are formed by the union of 2 monosaccharides Biomolecules: carbohydrates and lipids / Oligosaccharides and Disaccharides

We classify polysaccharides into: Consist of long chains whose repeating units are of the individual monosaccharides. We classify polysaccharides into: RESERVE SUPPORT Example: Starch Example: Cellulose Biomolecules: carbohydrates and lipids > Polysaccharides

benzene, chloroform, and ethers. Lipids: hydrophobic chains Lipids, or fats, are organic compounds characterized by their hydrophobicity, or insolubility in polar liquids such as water, and lipophilicity, or solubility in apolar solvents such as benzene, chloroform, and ethers. Fats are macromolecules essential for living organisms Represent an energy reserve Are at the base of the structure of the cell membrane Biomolecules: carbohydrates and lipids > Lipids: hydrophobic chains

Groups of Lipids TRIGLYCERIDES WAXES STEROIDS PHOSPHOLIPIDS Biomolecules: carbohydrates and lipids > Groups of Lipids

1. Triglycerides Triglycerides are derived by the esterification of 1 molecule of glycerol with 3 fatty acid molecules. Biomolecules: carbohydrates and lipids > Triglycerides

1. Triglycerides: fats and oils Triglycerides in which saturated acids dominate, such as butter, appear as solids and are called fats. Triglycerides in which there is a strong presence of unsaturated acids are liquids and are called oils, abundant in fish. Biomolecules: carbohydrates and lipids > Triglycerides: fats and oils

2. Waxes Waxes are a rather heterogeneous mixture of compounds of alcohols, ketones, alkanes and especially of the esters of a fatty acid (palmitic acid, stearic acid etc.) together with an alcohol (cetyl, ceryl etc.), all of which have very long chains. Waxes are extremely insoluble in water and chemically inert. Waxes also provide an effective barrier against bacteria Biomolecules: carbohydrates and lipids > Waxes

3. Steroids Steroids are united by a base structure formed by 3 hexatomic rings and a pentatomic ring called sterane, which are linked to an aliphatic chain and an –OH group. The best known of the steroids is cholesterol. Biomolecules: carbohydrates and lipids > Steroids

Phospholipids Phospholipids (or glycerophospholipids) are derived from the esterification of glycerol, like the triglycerides, but, unlike the latter, have two fatty acid molecules and a molecule of phosphoric acid, to which, in general, a choline group is linked. Biomolecules: carbohydrates and lipids > Phospholipids

Amphipathic nature The phosphate group is the hydrophilic ‘head’ of the molecule while the two lipid chains are the hydrophobic ‘tail’. The double nature of the phospholipid molecules are termed amphipathic. Biomolecules: carbohydrates and lipids > Amphipathic nature

Bilayers structure: the cell membrane In liquid, phospholipids line up spontaneously next to each other, aligning the lipid chains and turning the hydrophilic heads towards the water. The cell membrane, appropriately called a “phospholipid bilayer”, is an example of bilayers structure in line with the model proposed by Singer and Nicolson in 1972 that has been further improved with the so-called “fluid mosaic” model. Biomolecules: carbohydrates and lipids > Amphipathic nature