Molecules of Life – Biomolecules http://www.dnareplication.info/images/dnadoublehelix2.jpg What Do These Pictures Have in Common? gov.mb.ca k8science.org nuclearfamilywarhead.com gsbs.utmb.edu Brain Tissue learn.genetics.utah.edu Protein Structure – the correct protein structure is important for normal function new-science-press.com Prions Dr. Stanley Prusiner. cmu.edu stanford.edu Why Is Carbon So Important? Organic/Inorganic Molecules • Organic vs. Inorganic in Chemistry – Organic refers to molecules containing a carbon skeleton – Inorganic refers to carbon dioxide and all molecules without carbon Carbon’s Versatility • Carbon atoms are versatile and can form up to four bonds (single, double, or triple) and rings • Functional Groups in organic molecules confer chemical reactivity and other characteristics – Determines how that molecule will function (For ex. whether it is polar [charged] or nonpolar [uncharged]) Common Elements Found in Living Organisms • • • • • Carbon (C) Hydrogen (H) Nitrogen (N) Oxygen (O) Phosphorous (P) Organic Molecule Synthesis • Biomolecules are polymers (chains) of subunits called monomers Dehydration Synthesis • Monomers are joined together through dehydration synthesis – An H and an OH are removed, resulting in the loss of a water molecule (H2O) Hyrolysis • Polymers are broken apart through hydrolysis (“water cutting”) – Water is broken into H and OH and used to break the bond between monomers Biological Molecules • All biological molecules fall into one of four categories – Carbohydrates – Lipids – Proteins – Nucleic Acids 1. Carbohydrates • Carbohydrate composition – Made of C, H, and O in the ratio of 1:2:1 • Construction – Simple or single sugars are monosaccharides – Two linked monosaccharides are disaccharides – Long chains of monosaccharides are polysaccharides Carbohydrates • Carbohydrates are important energy sources for most organisms Monosaccharides • Basic monosaccharide structure – Backbone of 3-7 carbon atoms – Many –OH and –H functional groups – Usually found in a ring form in cells • Example monosaccharides – Glucose (C6H12O6): the most common Monosaccharides • Fate of monosaccharides inside a cell – Some broken down to free their chemical energy – Some are linked together by dehydration synthesis for storage Disaccharides • Disaccharides are two-part sugars – Sucrose (table sugar) = glucose + fructose – Lactose (milk sugar) = glucose + galactose – Maltose (malt sugar)= glucose + glucose Polysaccharides Used For Energy Storage • Monosaccharides are linked together to form chains (polysaccharides) • Storage polysaccharides – Starch (polymer of glucose) • Formed in roots and seeds as a form of glucose storage – Glycogen (polymer of glucose) • Found in liver and muscles Polysaccharides Used For Structural Support • Structural polysaccharides – Cellulose (polymer of glucose) – Found in the cell walls of plants • Indigestible for most animals due to orientation of bonds between glucoses nsf.gov Polysaccharides Used For Structural Support • Structural polysaccharides continued – Chitin (polymer of modified glucose units) • Found in the outer coverings of insects, crabs, and spiders • Found in the cell walls of many fungi 2. Lipids • All lipids contain large chains of nonpolar hydrocarbons (a chain of carbon atoms w/hydrogen atoms attached) • Most lipids are hydrophobic (don’t like water) and water insoluble (don’t dissolve in water) • Lipids are diverse in structure and serve in a variety of functions – Energy storage – Waterproofing – Membranes in cells – Hormones 3 Groups of Lipids • 1. Oils, fats, and waxes • 2. Phospholipids • 3. Steroids Oils, Fats, and Waxes • Made of only C, H, and O • Made of one or more fatty acid subunits – Long chains of C and H with a carboxylic acid group (-COOH) at one end • Fats and oils – Formed by dehydration synthesis Oils and Fats • Fats and oils used for long-term energy storage – Fats and oils possess a high density of stored chemical energy Oils and Fats • Fat solidity is due to single or double carbon bonds – Fats that are solid at room temperature are saturated (carbon chain has as many hydrogen atoms as possible, and mostly or all C-C single bonds), e.g. beef fat Oils and Fats • Fat solidity is due to single or double carbon bonds (continued) – Fats that are liquid at room temperature are unsaturated (fewer hydrogen atoms, many C=C double bonds), e.g. corn oil Waxes • Composed of long hydrocarbon chains and are strongly hydrophobic • Highly saturated and solid at room temperature • Form waterproof coatings • Used to build honeycomb structures Phospholipids • Form plasma membranes around all cells • Phospholipids have hydrophobic and hydrophilic portions – Polar functional groups are water soluble – Nonpolar fatty acid “tails” are water insoluble Steroids • Steroids are composed of four carbon rings fused together • Examples of steroids – Cholesterol • Found in membranes of animal cells – Male and female sex hormones 3. Proteins • Proteins have a variety of functions – Enzymes catalyze (speed up) reactions – Structural proteins (e.g. collagen) provide support Amino Acids • Proteins are formed from chains of amino acids (monomers) – There are 20 amino acids that make up proteins of living things. Amino Acids • All amino acids have similar structure – Central carbon atom bonded to four different functional groups • • • • 1. 2. 3. 4. An amino group (-NH2) A carboxylic acid group (-COOH) A hydrogen (H) All have a variable “R” group – – – Some R groups are hydrophobic Some are hydrophilic Cysteine R groups can form disulfide bridges Amino Acids • The sequence of amino acids in a protein dictates its function Dehydration Synthesis • Amino acids are joined to form chains by dehydration synthesis – An amino group reacts with a carboxyl group, and water is lost Dehydration Synthesis • Resultant covalent bond is a peptide bond • A chain of two amino acids or a short amino acid chain is called a peptide • Long chains of amino acids are known as polypeptides or just proteins Three Dimensional Structures • The type, position, and number of amino acids determine the structure and function of a protein – Precise positioning of amino acid R groups leads to bonds that determine structure – Disruption of these bonds leads to denatured proteins and loss of function • For ex. If you expose a protein to high temperatures, it will cause the protein to unfold, in other words, to denature. 4.Nucleic Acids • Nucleotides are the monomers of nucleic acid chains • All nucleotides are made of three parts – Phosphate group – Five-carbon sugar – Nitrogen-containing base Molecules of Heredity • Two types of nucleotides – Ribonucleotides (A, G, C, and U) found in RNA • • • • A = adenine G = guanine C = cytosine U = uracil – Deoxyribonucleotides (A, G, C, and T) found in DNA • • • • A = adenine G = guanine C = cytosine T = thymine Molecules of Heredity • Two types of polymers (chains) of nucleic acids – DNA (deoxyribonucleic acid) found in chromosomes • Carries genetic information needed for protein construction – RNA (ribonucleic acid) • Copies of DNA used directly in protein construction One nucleotide Molecules of Heredity • Each DNA molecule consists of two chains of nucleotides that form a double helix • The nucleotides on opposing strands form hydrogen bonds, linking the two strands • RNA is copied from DNA in the nucleus – That information is used to synthesize proteins in the cell’s cytoplasm The End