BIO 201 Chapter 2 Notes Dr Sonja Pyott Chemical Basis of Life Part II Concept 1 Carbon atoms form four covalent bonds with other atoms to generate a variety of molecules I Terms to know Macromolecule Hydrocarbon Functional groups Isomer II Carbon is the building block of organic molecules Carbon has four valence electrons so it needs four more to fill its outer shell completely Carbon will bond with a variety of atoms to generate a diversity of molecules Carbon can bond to hydrogen to form hydrocarbons examples include methane ethane and ethene or with more complex functional groups III Functional groups impart specific chemistry to organic molecules A Functional groups are complex groups of atoms that have special chemical features and are often involved in chemical reactions B Examples to know include Methyl Hydroxyl Carbonyl Carboxyl Amino Sulfyhydryl Phosphate IV Organic molecules can exist as isomers A Isomers are molecules that have similar numbers but different arrangements of atoms B Three types include Stuctural Geometric Enantiomeric Page 1 of 6 BIO 201 Chapter 2 Notes Dr Sonja Pyott Concept 2 Most macromolecules are built from monomers covalently linked to form polymers I Terms to know Polymer Monomer Dehydration reaction Hydrolysis II Most polymers are formed via dehydration reactions in which one molecule donates a hydroxyl group OH and one donates a hydrogen H to form a covalent bond and release one water molecule H20 III Polymers are broken down into monomers via hydrolysis reactions that require energy and are catalyzed by enzymes Concept 3 Carbohydrates are sources of energy and provide structure I Terms to know Carbohydrate Monosaccharide Disaccharide Polysaccharide Glycosidic bond II Carbohydrates are composed of C H and O and have the general chemical formula Cn H20 n So carbohydrates really are hydrated carbon atoms III Most carbohydrates end with the suffix ose like sucrose which is table sugar IV Carbohydrates can be either simple sugars including monosaccharides and disaccharides or polysaccharides A Monosacchardides Composed of a single sugar monomer Contain three to six carbons Common examples include Table 1 Example Glyceraldehyde Number of Carbons 3 Trioses Biological Role Component of the metabolic Page 2 of 6 BIO 201 Chapter 2 Notes Ribose Deoxyribose Glucose 5 Pentoses 6 Hexoses Dr Sonja Pyott intermediate glyceraldehyde 3 phosphate Component of RNA and DNA Primary source of energy for most living organisms Fructose Simple sugar often found in plants Galactose Simple sugar often found in dairy products B Disaccharides Composed of two monosaccharides joined covalently via a dehydration reaction The covalent bond between two monosaccharides is called a glycosidic bond Common examples include Table 2 Example Monomer components Sucrose Fructose and glucose Lactose Galactose and glucose Maltose 2 Glucoses Common sources Table sugar Produced by plants and is the most common sweetener Milk sugar Found in milk and requires the enzyme lactase to be digested broken down into galactose and glucose Malt sugar Produced by malting grains and accounts for the sweetness of malted beverages including beer and malted milkshakes and malt vinegar C Polysaccharides Composed of hundreds to thousands of monosaccharides joined by glycosidic bonds Have two main functions Table 3 Example Starch polysaccharide of glucose Cellulose polysaccharide of glucose Chitin Function Energy storage Common sources Many plants especially potatoes and grains Structural support Plant cell walls Arthropod exoskeletons Page 3 of 6 BIO 201 Chapter 2 Notes Dr Sonja Pyott Concept 4 Lipids are hydrophobic molecules that store energy form membranes and serve as hormones I Terms to know Fat Glycerol Fatty acid Phospholipid Polar head group Nonpolar tail group Micelle Bilayer Steroid II Lipids are composed primarily of carbon and hydrogen and are therefore nonpolar and hydrophobic III Additional molecular components distinguish the three classes IV There are three classes of lipids Table 4 Class of Lipid Fats Phospholipids Steroids Subunits 1 glycerol bonded to 3 fatty acids which can be either saturated or unsaturated 1 glycerol bonded to 2 fatty acids and 1 phosphate group 4 fused carbon rings with various attached functional groups Predominant Role Energy storage Important component of cell membranes because they form lipid bilayers in aqueous environments Include cholesterol and sex hormones Concept 5 Nucleic Acids store and transmit hereditary information I Terms to know Deoxyribonucleic acid DNA Ribonucleic acid RNA Nucleic acid Nucleotide Nitrogenous base Purine Page 4 of 6 BIO 201 Chapter 2 Notes Dr Sonja Pyott Pyrimidines Pentose Deoxyribose Ribose II There are two types of nucleic acids Deoxyribonucleic acid DNA is used for storage of hereditary information Ribonucleic acid RNA is used for expression of hereditary information Note The text goes into the structure of DNA and also the flow of genetic information from gene to RNA to protein You do NOT need to know this material for Exam 1 However we will go into these topics in more detail in later Modules so it is worth your time to preview the material here III Nucleic acids are polymers of nucleotides IV Nucleotides consist of three subunits A Nitrogenous base Purines Adenine A and Guanine G Pyrimidines Thymine T Cytosine C in DNA and Uracil U in RNA B Pentose 5 carbon sugar Ribose sugar in RNA Deoxyribose sugar in DNA C Phosphate Donates H to solution at physiological pH Makes nucleic acids acidic V Nucleotides can also be important energy molecules Examples ATP NAD and FAD Concept 6 Proteins have a variety of structures and functions I Terms to know Protein Polypeptide Peptide bond Amino acid Conformation Primary structure Secondary structure Page 5 of 6 BIO 201 Chapter 2 Notes Dr Sonja Pyott Tertiary structure Quaternary structure Domains Motifs Chaperone proteins Denaturation Renaturation Dissociation II Proteins are one or more polypeptides in a specific conformation 3D structural arrangement III Polypeptides are polymers of amino acids linked via dehydration reactions by peptide bonds IV There are 20 common amino acids each consisting of a central carbon atom covalently attached to An amino group NH2 A carboxyl group COOH which donates a H to solution at physiological pH and makes amino acids acidic A hydrogen H An R group that determines the chemistry of the amino acid V Proteins have levels of structural organization summarized in