8 20 2013 Chemical basis of life Part II Chapter 3 Carbon is the building block of organic molecules Figure 3 2 Functional groups impart specific chemistry to organic molecules Functional groups are Examples to know include Table 3 1 commonly occurring groups of atoms in a Methyl molecule that Hydroxyl participate in Carbonyl characteristic reactions Carboxyl Amino Phosphate Sulfate Sulfhydryl 1 8 20 2013 Name Amino NH2 Characteristics Basic positively charged R Example Amines amino acids Name Carbonyl CO Characteristics Polar R R or H Example Ketones like acetone aldehydes and sugars Name Carboxyl COOH Characteristics Acidic negatively charged R Example Acids like acetic acid 2 8 20 2013 Name Hydroxyl OH R Characteristics Very polar hydrophilic Example Alcohols like ethanol sugars Name Phosphate PO4 2 Characteristics Acidic negatively charged R Example Organic Example phosphates ATP glycerol phosphate Name Sulfhydryl SH R Characteristics Can form disulfide bridges Example Thiols 3 8 20 2013 Name Methyl CH3 Characteristics Nonpolar hydrophobic R Function methylation can affect gene expression protein function and other biological functions Functional groups change the function of molecules Figure 3 13 Biological molecules some terms Biological molecules are typically large molecules polymers constructed from smaller subunits monomers Mer Mono Poly 12 4 8 20 2013 Biological Molecules Dehydration reactions Hydrolysis breaks down Compare to Figure 3 5 Four classes of biological molecules 1 Proteins 2 Carbohydrates 3 Lipids 4 Nucleic acids http www jelks coffee com newshop contents media dots jpg http en wikipedia org wiki File NCI butter jpg http www balehoo com wp content uploads 2008 06 Steak 20basel gif Raven Biology Proteins Proteins are one or more polypeptides folded into a specific 3D structural arrangement Polypeptides are polymers of amino acids linked via dehydration reactions by peptide bonds There are 20 common amino acids each consisting of a central carbon atom covalently attached to 5 8 20 2013 20 amino acids found in living organisms Figure 3 14 Peptide bonds join amino acids to form a polypeptide Compare to Figure 3 15 Proteins have many functions Function Examples Catalysis Enzymes Support Structural proteins like keratin Defense Immunoglobins and toxins Transport Hemoglobin Motion Actin and myosin Regulation Hormones like insulin Storage Casein Compare to Table 3 2 6 8 20 2013 Proteins have a hierarchy of structure 1 Primary structure 2 Secondary structure 3 Tertiary structure Figure 3 16 4 Quaternary structure Primary structure the linear sequence of amino acids in a protein Figure 3 16 Secondary structure regions of folds and coils due to hydrogen bonding Examples pleated sheets and helices Compare to Figure 3 16 7 8 20 2013 Tertiary structure 3D shape of a protein determined by interactions among various side chains R groups Examples hydrogen bonds disulfide bridges and ionic bonds Compare to Figure 3 16 Quaternary structure overall shape of a protein due to association of multiple polypeptide subunits Examples collagen is a multimeric protein consisting of three coiled collagen polypeptides Compare to Figure 3 16 Factors that influence protein folding and stability 2 Ionic bonds 1 Hydrogen bonds 3 Hydrophobic effects 4 Disulfide bridges 5 Van der Waals forces Figure 3 18 8 8 20 2013 The conformation of proteins is critical to their function Denaturation is the loss of a protein s conformation and usually renders the protein biologically inactive Chaperone proteins chaperonins Defects in protein conformation can cause disease example sickle cell anemia Carbohydrates Simple sugars have an empirical formula of CH2O n So they really are hydrated carbons Because C H covalent bonds hold a lot of gy carbohydrates y are ggood energy gy storage g energy molecules Typically categorized as monosaccharides monomers disaccharides dimers and polysaccahrides polymers 26 Monosaccharides Number of Carbons Example Biological Role 3 Trioses Glyceraldehyde Metabolic intermediate 5 Pentoses Ribose y Deoxyribose Component of RNA and DNA Glucose Primary source of energy for most living organisms Fructose Simple sugar often found in plants 6 Hexoses Galactose Simple sugar often found in dairy products 9 8 20 2013 Disaccharides Composed of two monosaccharides joined covalently via a dehydration reaction The covalent bond between two monosaccharides is called a Figure 3 7 Common disaccharides Example Monomer components Common sources S Sucrose F t Fructose and d glucose l T bl sugar Table Lactose Galactose and glucose Milk sugar Maltose 2 glucoses Malt sugar Polysaccharides Composed of hundreds to thousands of monosaccharides joined by glycosidic bonds Function Energy storage Example Starch Glycogen Structural support Cellulose Chitin Common sources p Manyy plants especially potatoes and grains Animal cells Plant cell walls Arthropod exoskeletons http www bigoven com uploads Cornstarch jpg 10 8 20 2013 Structure of polysaccharides Figure 3 8 Lipids Contain a high proportion of nonpolar hydrocarbon bonds which causes them to be Great molecule for energy storage and Hydrophobic and insoluble in water Three main types include Fats triacylglycerols Phospholipids Steroids Fats triacylglycerols Composed of 1 glycerol and 3 fatty acid molecules joined by an ester bond Compare to Figure 3 9 11 8 20 2013 Fats triacylglycerols Composed of 1 glycerol and 3 fatty acid molecules joined by an ester bond Compare to Figure 3 9 Fatty acid chains can saturated or unsaturated Figure 3 10 Phospholipids Composed of 1 glycerol 2 fatty acids and 1 phosphate group with a choline Amphipathic Essential components of biological membranes Figure 3 12 12 8 20 2013 Phospholipids spontaneously organize in aqueous solutions Phospholipid head regions are oriented toward the hydrophilic environment and the hydrophobic tails orient away from the hydrophilic environment http www bio miami edu cmallery 255 255chem mcb2 20 micelle jpg Steroids Lipids characterized by a carbon skeleton containing four fused rings shown in yellow Vary by the functional groups added to those four fused rings Include cholesterol and sex hormones Cholesterol Compare to Figure 3 13 Cholesterol can be converted to steroid hormones Figure 3 13 13 8 20 2013 Nucleic Acids There are two types of nucleic acids Deoxyribonucleic acid DNA is used for storage g of hereditaryy information Ribonucleic acid RNA is used for expression of hereditary