BIOL 1103 1st Edition Exam 2 Study Guide Summary of the Readings Biological Molecules Carbohydrates Macromolecules that serve as structural support for the cells and as an energy source Monosaccharides are simple sugars Isomeric monosaccharides are glucose galactose and fructose Disaccharides are formed when two monosacchrides undergo dehydration reaction removal of water molecules Disaccharides are lactose glucose galactose maltose glucose glucose and sucrose glucose fructose Polysaccharides are a long chain of monosaccharides liked covalently Examples are starch glycogen cellulose and chitin Starch is sugar stored in plants Animals break starch down into glucose particles Glycogen is glucose stored in humans and other vertebrates It is the equivalence of starch but in animals Cellulose is the cell walls of plants and humans cannot digest it Chitin makes up the exoskeleton of arthropods Lipids Lipids are hydrophobic which means water fearing because they are non polar molecules Functions include cells store energy insulation building blocks of hormones and make up plasma membrane Examples are fats oils phospholipids steroids and waxes Fat consists of glycerol and fatty acids Fatty acids have long chains of hydrocarbons with an attached acidic carboxyl group Triglycerides are a fat molecule that consists of three fatty acids attached to a glycerol molecule Saturated fatty acids are saturated with carbon and are solid at room temperature animal fats They contribute to cholesterol build up Unsaturated fatty acids contain double bonds of hydrocarbon chains are oils and liquid at room temperature They help to improve blood cholesterol levels If the oil has one double bond it is monounsaturated and if it has more than one double bond it is polyunsaturated Essential fatty acids must be contained through the diet Phospholipids are the major constituent of the plasma membrane and have hydrophobic water fearing and hydrophilic water loving parts Steroids Steroids have a ring stricter and the main steroid is cholesterol Waxes are made up of a fatty acid and a hydrocarbon chain with an alcohol group Proteins Proteins are the most abundant organic molecule in the living system Functions include structural regulatory contractile protective transport storage or membranes Enzymes are catalysts in reactions and are usually proteins Hormones are chemical signaling molecules that can be proteins Their functions include growth development metabolism and reproduction There are 20 different amino acids Amino acids make up protein The sequence and number of amino acids determine the protein s shape function and size Polypeptides are polymers of amino acids Protein Structure Proteins are organized at four different levels primary secondary tertiary and quaternary The protein shape determines its function and any change caused by changes in pH temperature or chemical exposure may lead to protein denaturation loss of shape or loss of function Nucleic Acid Nucleic acids are DNA genetic material and RNA protein synthesis Nucleotides are monomers that make up DNA and RNA DNA has a double helical structure and is composed of two strands of nucleotides Enzymes Enzymes are proteins that catalyze biochemical reactions and lower the activation energy of chemical reactions in order to speed up reactions Substrates are chemical reactants to which an enzyme binds In a single reactant it is broken down into multiple products The active site is where the substrate binds in the enzyme It is where the action occurs The local environment like pH and temperature can influence them As the substrate and enzyme come together their interaction cause a shift in the enzyme s structure that forms the ideal binding arrangement This is what lowers the activation energy Enzyme action is regulated to conserve recourses and respond optimally to the environment Translation Protein Synthesis Machinery Translation requires the input of an mRNA template ribosomes tRNAs and various enzymatic factors Ribosomes have small subunits that are responsible for binding the mRNA template and the large subunit binds tRNA brings amino acids to the polypeptide chain Codon is a three nucleotide sequence that defines amino acids The genetic code is the relationship between a codon and its amino acid Translation includes the mRNA template ribosomes tRNA and various enzymatic factors Summary of Class Notes Food Molecules Carbohydrates energy storage and cell surface molecules On a food label look for Total Carbohydrates o Monosaccharides simple sugars Fructose glucose and galactose On a food label they are found under total carbohydrates and listed as sugars o Disaccharides two simple sugars sucrose table sugar lactose sugar in milk and maltose On a food label they are found under total carbohydrates and listed as sugars o Polysaccharides starch fiber cellulose and glycogen These are found under total carbohydrates as dietary fiber Lipids stored energy membranes and steroid hormones On a food label the lipids can be found under Total Fat o Triglycerides have a main unit of glycerol and three prongs of fatty acids o Fats are solid at room temperature enriched in animal sources and coco and palm and are saturated in hydrogen Fats structures are more of a straight line o Oils are liquid at room temperature enriched in plant sources like seeds and unsaturated Oil s structure curves Steroids four fused rings of carbon and are hormones estrogen and testosterone The largest hormone is cholesterol which only comes form animal food o Cholesterol Bad LDL low density lipoprotein carries cholesterol to cells Good HDL high density lipoprotein carrying cholesterol to liver for elimination Proteins function as structures enzymes protection hormones signaling ect o Amino Acids are the building blocks for protein There are 20 different amino acids There are 8 essential amino acids that we cannot make so they must be obtained in our diet These 8 essential amino acids can be found in animal proteins but vegetable protein may lack some Enzymes Two metabolic pathways that are taken are catabolic reactions break down and release energy and anabolic reactions build up and require energy Cells need enzymes because they are proteins that catalyze biochemical reactions and lower the activation energy of chemical reactions in order to speed up reactions If an enzyme stopped working all of the chemical reactions in the body would slow down and the function could not be preformed