Bios 208 1st Edition Lecture 10Outline of Last Lecture I. Glycosidic linkagesII. Cellulose digestionIII. ChitinIV. LipidsV. Fats and OilsVI. The structure of a phospholipidOutline of Current Lecture I. CholesterolII. Protein FunctionsIII. Amino acidsIV. Amino Acid PolymersV. Protein StructureVI. Sickle-Cell Disease: A Change in Primary StructureVII. Nucleic Acids VIII. Nucleotide Polymers IX. Structures of DNA and RNA MoleculesCurrent LectureI. CholesterolA. Cholesterol is a steroid. It has 4 fused rings (found in all steroids), plus a short hydrocarbon tail and a hydroxyl group. It is a component of lipid bilayers.B. Cholesterol can regulate membrane fluidity when inserted in to lipidBilayer.C. A Key Concept: Relationship between DNA and protein synthesis…a flow of information.D. There are two types of nucleic acids: Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA).E. DNA provides directions for its own replication.F. DNA also directs synthesis of messenger RNA (mRNA); known as“transcription.”mRNA, encodes protein synthesis via the assembly of amino acid monomers to make polypeptide polymers; known as “translation.”These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.G. Protein synthesis occurs on ribosomes in cells.II. Protein FunctionsA. Protein is a biologically functional molecule that consists of one or more polypeptides.a) Enzymes (make/break bonds) as catalystsb) Defense against disease/antibodiesc) Amino acid storaged) Transport across membranese) Hormonesf) Receptorsg) Cell motilityh) Structure and supportB. Enzymatic proteinsa) Function: Selective acceleration of chemical reactions.b) Example: Digestive enzymes catalyze the hydrolysis of bonds in food molecules.C. Defensive proteinsa) Function: Protection against disease.b) Example: Antibodies inactivate and help destroy viruses and bacteria.D. Storage proteinsa) Function: Storage of amino acids.b) Examples: Casein, the protein of milk, is the major source of amino acids for baby mammals. Plants have storage proteins in their seeds. Ovalbumin is the protein of egg white, used as an amino acid source for the developing embryo.E. Transport proteinsa) Function: Transport of substances.b) Examples: Hemoglobin, the iron-containing protein of vertebrate blood, transports oxygen from the lungs to other parts of the body. Other proteins transport molecules across cell membranes.F. Hormonal proteinsa) Function: Coordination of an organism’s activities.b) Example: Insulin, a hormone secreted by the pancreas, causes other tissues to take up glucose, thus regulating blood sugar concentrationG. Receptor proteinsa) Function: Response of cell to chemical stimuli.b) Example: Receptors built into the membrane of a nerve cell detect signaling molecules released by other nerve cells.H. Contractile and motor proteinsa) Function: Movement.b) Examples: Motor proteins are responsible for theundulations of cilia and flagella. Actin and myosinproteins are responsible for the contraction of muscles.I. Structural proteinsa) Function: Support.b) Examples: Keratin is the protein of hair, horns,feathers, and other skin appendages. Insects and spiders use silk fibers to make their cocoons and webs,respectively. Collagen and elastin proteins provide a fibrous framework in animal connective tissues.III. Amino acidsA. Amino acids are organic molecules with carboxyl and amino groups.B. Amino acids differ in their properties due to differing side chains, called R groups.C. Polypeptides are unbranched polymers built from the same set of 20 amino acids.D. Amino acids are the subunits of proteins.E. The alpha-carbon has 4 groups attached; 1-3 are common to all amino acids.a) Amino groupb) Carboxyl groupc) Hd) R-group. Each of the 20 amino acids found in proteins has a different R-group.IV. Amino Acid PolymersA. Amino acids are linked by peptide bonds.B. A polypeptide is a polymer of amino acids.C. Polypeptides range in length from a few to more than a thousand monomers.D. Each polypeptide has a unique linear sequence of amino acids, with a carboxyl end (C-terminus) and an amino end (N-terminus).E. Polypeptide synthesis involves the carboxyl group of one AA with the amino group of another AA.F. Dehydration synthesis reaction.G. Peptide backbone has repeating pattern: NCC-NCC-NCC-.H. The first AA is at the amino end (N-terminus).I. Each new AA is added to the carboxyl end (C-terminus).J. R-groups (side chains) stick out.K. The AA chain is a polypeptide.V. Protein StructureA. A functional protein consists of one or more polypeptides precisely twisted, folded, and coiled into a unique shape.B. The coils and folds of secondary structure result from hydrogen bonds between repeating constituents of the polypeptide backbone.C. Typical secondary structures are a coil called anα helix and a folded structure called a βpleated sheet.D. The primary structure of a protein is its unique sequence of amino acids.a) Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain.b) Tertiary structure is determined by interactions among various side chains (R groups).c) Quaternary structure results when a protein consists of multiple polypeptide chains.E. Order or sequence of AAs.F. Every protein has precise chainlength and a specific AA ateach position (e.g., transthyretinhas 127 AAs).G. Number of possible sequences = 20n.H. 20 is the number of letters in the.I. Amino Acid “alphabet” n is the number of AAs in the chain.J. A protein’s FUNCTION is dependent on its overall 3D STRUCTURE.K. Lysozyme (an enzyme) can kill bacteria by destroying their cell walls, but only if the enzyme is in its “native conformation”.L. Tertiary structure is determined by interactions between R groups, rather than interactions between backbone constituents.M. These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions.N. Strong covalent bonds called disulfide bridges may reinforce the protein’s structureO. Quaternary structure results when two or more polypeptide chains form one macromolecule.P. Collagen is a fibrous protein consisting of three polypeptides coiled like a ropeQ. Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains.R. In addition to primary structure, physical and chemical