Biological Molecules

Macromolecules: Very large molecules. Monomers: One, the can exist on their own. Polymers: compound of monomers. Consideral building blocks of biological molecules. Large Biological Molecules: Carbohydrates: Simple sugars or polymers of sugars. Monosaccharides: Single sugars. C-based, commonly contain 3-7C atoms. Highly H₂O soluble. Contain 2 or more -OH groups. Exist in ring or linear form. Disaccharides: 2 sugars bonded. Formed by condensation reaction between 2 monosaccharides. Polysaccharides: Many sugars. True macromolecules. Polymers of 100s to 1000s. Product of condensation synthesis. Highly H₂O soluble while longer chains get big & bulky. Not digested by humans. Subgroups: Starch & glycogen: energy reserve form Cellulose: glucose polymer, can't be digested by humans Lipids: Large biological molecules. Not true polymers. Hydrophobic (water-fearing). Subgroups: Fats (e.g., oils): hydrophobic Phospholipids: amphipathic Steroids: hydrophobic Condensation Reaction/Dehydration Reaction: Formation of a covalent bond with the loss of a water molecule. Used to attach a monomer to a growing polymer. Depending on how many rounds of condensation occur, can lead to small polymers or all the way to large biological molecules. Hydrolysis: Breaks apart a bond via the addition of water. Releases monomers. Occurs in macromolecules to: Remove damaged molecules. Release macromolecules no longer needed. Both C.S and hydrolysis are tightly regulated on a cellular level, as cellular chaos would occur if reactions were random. Four major groups of large biological molecules: Carbohydrates Proteins Lipids Nucleic Acids (DNA & RNA) Nucleic Acids: Large biological molecules. Polymers of nucleotides. DNA (deoxyribonucleic acid) & RNA (ribonucleic acid) Title: Biological Molecules **Fats:** * Will NOT dissolve in water (polar solvent) * Formed by 3 fatty acids + 1 glycerol backbone * 3 condensation reactions * 3 water molecules lost **Fatty Acids:** * Saturated Fatty Acids * No double bonds (C=C) * Saturated with Hydrogen * Linear chain * Solid at room temp * Unsaturated Fatty Acids * One or more double bonds (C=C) * Monounsaturated (1 C=C bond) * Polyunsaturated (2+ C=C bonds) * Cis or Trans configuration * Cis: Hydrogens on same side of the double bond * Trans: Hydrogens on opposite sides of the double bond * Degree of unsaturation affects fluidity * Cis & Trans cis isomers affect fluidity differently * Saturated fats: * Solid at room temp * Liquid at high temp * Unsaturated fats: * Liquid at room temp **Trans vs. Cis Fatty Acids:** * Trans fatty acids formed during processing of cis fatty acids * Hydrogenation used to reduce unsaturated fatty acids to saturated fats and prevent spoilage * Isomerization happens sometimes during hydrogenation * Trans fatty acids are packed tightly and can clog arteries * Cis fatty acids are bent and less likely to clog arteries **Steroids:** * Hydrophobic, non-fatty lipid * 4 fused rings (steroid structure) * Cholesterol * Major steroid * Precursor for many other steroids * Component of cell membranes **Proteins:** * Macromolecules * Amino acids are monomer subunits of proteins * 20 different amino acids * Proteins have a structural role * Proteins have a catalytic role * Humans cannot synthesize all 20 amino acids * Different amino acids have different side chains (R groups) * Amino acids contain an asymmetric (chiral) carbon atom * Some amino acids are essential and must be obtained from the diet. [Image of amino acid structure] * Cellular skeleton * Multicellular animals have a lot of extracellular collagen **Protein Terminology** **Protein** * Held together by peptide bonds. Peptide bond formation is a condensation/dehydration reaction. * R groups do not take part in peptide bond formation. * A string of 10+ linked amino acids (polypeptide chain) **Levels of Structure** * All proteins have primary (1°), secondary (2°), and tertiary (3°) structure. * Primary structure is a linear sequence of amino acids. * Secondary structure is the α-helix and β-pleated sheet. * Tertiary structure is the 3D shape of the functional protein. It is the sum of 2° and 3° structure. * Some proteins have quaternary (4°) structure. These are composed of 2+ polypeptide subunits. * 2+ polypeptides interact to form the functional protein. * Does NOT include 1° structure. * They interact in a 3D space. **Denaturation** * Change in 3-D structure of a protein due to a change in the environment of the protein. * Change in pH, ion concentration, solvent * Not all changes are reversible. * Ex: High temperature results in irreversible denaturation. * Requires protein in correct environment (pH, salt concentration, etc.) * Protein denaturation is a change in conformation away from the native conformation.