Biomolecules: Lipids, Carbohydrates, Proteins, and Nucleic Acids PDF

LIPIDS What are they? Compounds that are generally hydrophobic (do not mix well with water). Unlike proteins and carbohydrates, they generally don’t form large polymers. Includes fats, waxes, sterols, phospholipids, vitamins What do we use them for? Typically, lipids are involved in energy storage,...

LIPIDS What are they? Compounds that are generally hydrophobic (do not mix well with water). Unlike proteins and carbohydrates, they generally don’t form large polymers. Includes fats, waxes, sterols, phospholipids, vitamins What do we use them for? Typically, lipids are involved in energy storage, lipid bilayers that are involved with membranes, and also as signalling molecules. Dietary fats O Palmitic (16:0) HO O Stearic (18:0) HO O Oleic (18:1) HO O Linolenic (18:3) HO O Docosahexanoic HO (22:6) Saturated vs nonsaturated fats Saturated fats Present in dairy, meat fat, palm & coconut oil Implicated in raising LDL levels Increased LDL levels are associated with heart disease Omega fatty acids Omega fatty acids are essential fatty acids Common sources are fish and flaxseed oil Most fats are stored as triacylglycerides Triacylglycerides (TAGs) are made up of glycerol (a 3-carbon alcohol) and 3 fatty acids (a carboxyl group attached to a long carbon skeleton) Ester linkage Lipids in membranes Phospholipids consist of two fatty acids and a phosphate group attached to glycerol Hydrophobic tails Hydrophilic head Choline Phosphate Glycerol Fatty acids Hydrophilic head WATER Hydrophobic tail WATER Lipids as signaling molecules Estradiol Testosterone Lipids as vitamins CARBOHYDRATES What are they? Compounds that are hydrates of carbon – they generally have the formula C(H2O)n. Most are saccharides, which includes monosaccharides, polysaccharides, oligosaccharides and polysaccharides. What do we use them for? Like lipids, carbohydrates can be used to store energy, as signalling molecules, or as structural components. Simple carbohydrates Simple carbohydrates (a) Linear and ring forms (b) Abbreviated ring structure Simple carbohydrates Simple carbohydrates Disaccharides are joined by a glycosidic linkage 1–4 glycosidic linkage Glucose Glucose Maltose Sweetness Lactose Galactose Maltose Glucose Sucrose Fructose 16 32 33 74 100 173 Artificial Sweeteners Saccharin 300-500x sweeter Sodium cylamate 30-50x sweeter Artificial Sweeteners Aspartame 200x sweeter Sucralose 600x sweeter Complex carbohydrates = polysaccharides (a)  and  glucose ring structures  Glucose (b) Starch: 1–4 linkage of  glucose monomers  Glucose (b) Cellulose: 1–4 linkage of  glucose monomers Polysaccharides are energy stores Chloroplast Mitochondria Starch Glycogen granules 0.5 µm 1 µm Glycogen Amylose Amylopectin (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide Cellulose is a structural polysaccharide Cell walls Cellulose microfibrils in a plant cell wall Microfibril 10 µm 0.5 µm Cellulose molecules  Glucose monomer Carbohydrates for molecular recognition Many of our cells use carbohydrates attached to proteins (glycoproteins) and lipids (glycolipids) to recognise each other. PROTEINS What are they? A chain made up of amino acids joined by peptide bonds that forms a specific 3D structure What are amino acids? There are 20 different amino acids that have different functionalities, giving proteins distinct structures and functions What do we use them for? Used to build, maintain and repair the body, and make things like enzymes, antibodies and hormones Amino acids Amino acids in the diet Amino acids in the diet The peptide bond Protein structure Alpha helices Beta sheets Parallel and antiparallel beta sheets Tertiary Structure Chemical bonds maintain structure Hydrophobic interactions and van der Waals interactions Polypeptide backbone Hydrogen bond Disulfide bridge Ionic bond Quaternary Structure What happens when we unfold a protein? Denaturation Normal protein Renaturation Denatured protein Proteins function through specific recognition and binding of a target molecule Enzymes Structural Motors Channels Receptors Transporters Messengers Defence Proteins function through specific recognition and binding of a target molecule Enzymes: speed up chemical reactions are substrate specific are reaction specific Proteins function through specific recognition and binding of a target molecule Structural Collagen Motors Myosin Helicase Transporters, messengers Hemoglobin Insulin Defence Antibodies NUCLEIC ACIDS What are they? A chain made up of nucleotides joined by phosphodiester bonds that forms a specific 3D structure. The main nucleic acids are DNA and RNA What do we use them for? Used to store, transmit, and help express information Nucleic Acids are made up of nucleotides DNA and RNA have different nucleotides DNA and RNA molecules can form hydrogen bonds