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Organic Compounds Introduction to Carbon based or Organic Compounds Life’s structural and functional diversity results from a great variety of molecules. In addition to water, all other biological molecules are organic or carbon based molecules. Structural Ball-and-stick Space-filling formula model model Methane The 4 single bonds of carbon point to the corners of a tetrahedron. Life’s molecular diversity is based on the properties of carbon Carbon is unparalleled in its ability to form large, diverse molecules The outer electron shell of Carbon has 4 electrons Carbon completes its outer shell by sharing electrons with other atoms (Carbon and other elements) in 4 covalent bonds. Organic compounds Organic molecules are characterized by having a central “backbone” made of atoms of carbon linked to each other like a “chain” of carbon atoms. In addition, other atoms can link to the carbon backbone. The unique properties of an organic compound depend on the size and shape of its Carbon skeleton (the chain of Carbon atoms, can be branched or unbranched) and on the groups of atoms that are attached to that skeleton. Carbon skeletons vary in many ways Propane Ethane Length. Carbon skeletons vary in length. Butane Isobutane Branching. Skeletons may be unbranched or branched. 1-Butene Double bonds. Skeletons may have double bonds, which can vary in location. Cyclohexane Rings. 2-Butene Benzene Skeletons may be arranged in rings. Organic Compounds There are chemical “groups” that are important in the chemistry of life. These groups, known as functional groups (groups of atoms that always go together), affect the molecules function by participating in chemical reactions . The most important groups are (these are all polar): Hydroxyl group Consists of a Hydrogen bonded to an Oxygen (also known as alcohol group). Carbonyl group : Carbon linked by a double bond to an Oxygen Carboxyl group: A Carbon double-bonded to both an Oxygen and a Hydroxyl group (also known as an acid group) Amino group : Composed of a Nitrogen bonded to 2 Hydrogen atoms and the Carbon skeleton Phosphate group: Consists of a Phosphorus atom bonded to 4 Oxygen atoms Methyl group nonpolar and not reactive,Carbon bonded to 3 Hydrogen Organic Compounds How about a working example? Male and female sex hormones differ ONLY by functional group This change in functional group may seem subtle, but results in different actions of these molecules, which help produce the physical features (characteristics) of males and females Same structure, but different functional groups Estradiol – female sex hormone Female Lion Hydroxyl group Methyl group Testosterone – male sex hormone Carbonyl group (not on the list) Male Lion Biological Molecules In addition to water, all other biological molecules are organic (carbon-based) molecules. There are many organic molecules, but four of them are important to living organisms: Carbohydrates, Lipids, Proteins and Nucleic Acids. Most of the large molecules in living things are macromolecules called polymers. A polymer is a ‘macromolecule’ because of its great size. Polymers consist of many identical or similar building blocks (monomers) strung together, much like a long train consists of many individual cars Polymers The variety of polymers made by a cell is potentially endless The arrangement and number of monomers can lead to countless different polymers Many Carbohydrates and all lipids, proteins and nucleic acids are polymers! How do we build large molecules? Cells link monomers to form polymers by dehydration synthesis 1 2 3 4 Short polymer Unlinked monomer Removal of water molecule There is input of Energy 1 2 Enzyme catalyzes the reaction Longer polymer 3 4 This is an ENDERGONIC reaction. Why? Polymers are broken down to monomers by the reverse process, hydrolysis 1 There is an energy release 1 2 2 3 Addition of water molecule 3 4 Enzyme catalyzes the reaction 4 This is an EXERGONIC reaction. Why? Biomolecules Carbohydrates CARBOHYDRATES Carbohydrates are a class of molecules They include sugars, starches and fiber. Composed of the elements C, H and O Major source of energy from our diet Produced by photosynthesis in plants Types of Carbohydrates Monosaccharides Single monomer Disaccharides Contain 2 monosaccharide units Polysaccharides Contain many monosaccharide units Monosaccharides are the simplest carbohydrates. Monosaccharides are single-unit sugars Monosaccharides are the fuels for cellular work. We classify monosaccharides according to the number of carbons involved in the carbon chain. 5C and 6C are the most important. Examples of 6 C Monosaccharides H C O H C OH HO C H CH 2OH C O HO C H H O C H C OH HO C H H C OH H C OH H C OH H C OH H C OH CH 2OH CH 2OH CH2OH D-Glucose D-Fructose HO C H Galactose Honey Honey is a sweet, thick sugary solution made by bees. The composition of honey consists of varying proportions of fructose, glucose, water, oil and special enzymes produced by bees. It also has gluconic acid hydrogen peroxide that make honey inhospitable to bacteria, mold, and fungi, organisms we call microbes. Hunter of bees, Arana, Spain 7000 BCE Disaccharides Disaccharides are two unit sugars Disachharides are more complex fuels for cellular work. We form dissacharides using dehydration synthesis Energy Glucose + Glucose H2O Maltose Enzyme Enzyme Energy H2O Energy Glucose + Fructose Energy H2O Enzyme Enzyme Sucrose H2O Energy Glucose + Galactose Energy H2O Enzyme Enzyme Lactose H2O What is sucrose? Table Sugar! Primary Plant Sources of table sugar Sugar Cane – Saccharum officinarum Sugar Beet – Beta vulgaris Sorghum – Sorghum bicolor Palm – Phoenix dactylifera Maple – Acer saccharum The average USA sugar consumption per capita per year is 60 lbs. Oh Boy! All I need now is some sugar! Sugar Cane Saccharum officinarum – member of Poaceae (Grass family) Native to: Polynesia Sugar Cane Fields, Queensland Australia, Spring 2006 Sugar Beet, the sugar of temperate climates Beta vulgaris – Chenopodiaceae (Goosefoot Family) Sugar Beet Fields. Cornwall England, Summer 2006 North American Sweetener Acer saccharum – Sugar Maple Maple Syrup Sap is collected in early spring Sap is boiled in “sugar house” 40 gallons sap 1 gallon syrup What is lactose? Lactose is the dissacharide sugar found in milk! What is lactose intolerance? Are you lactose intolerant? Do you know somebody who is? Lactose intolerance is a condition that those who are afflicted cannot digest milk. This is the normal hydrolysis reaction Energy Glucose + Galactose Energy H2O Enzyme Enzyme Lactose H2O A lactose intolerant person does not have the enzyme that breaks down the lactose, therefore lactose is indigetable and it causes indigestion! How sweet is sweet? Various types of molecules, including non-sugars, taste sweet because they bind to “sweet” receptors on the tongue. Polysaccharides Polysaccharides are carbohydrates composed of many monosaccharides. There are two types of polysaccharides Storage Polysaccharides: They store energy Structural Polysaccharides: These are use for building cell structures. Polysaccharides are long chains of sugar units These large molecules are polymers of hundreds or thousands of monosaccharides linked by dehydration synthesis Energy 1. Glucose + Glucose H2O Enzyme Energy Maltose n(H2O) 2. Maltose + n(Glucose) Polysaccharide Enzyme n = many Starch and glycogen are storage polysaccharides that store sugar for later use. Cellulose is a structural polysaccharide in plant cell walls Starch granules in potato tuber cells Glycogen granules in muscle tissue Cellulose fibrils in a plant cell wall Cellulose molecules Glucose monomer STARCH GLYCOGEN CELLULOSE Starch is a storage polysaccharide composed entirely of glucose monomers. One unbranched form of starch, amylose, forms a helix. Branched forms, like amylopectin, are more complex. Animals that feed on plants rich in starch use it as a source of energy. Fig. 5.6a Animals also store glucose in a polysaccharide called glycogen. Glycogen is highly branched, like amylopectin. Humans and other vertebrates store glycogen in the liver and muscles for a short period of time. They only store one day supply. Insert Fig. 5.6b - glycogen Structural Polysaccharides Other polysaccharides, structural polysaccharides serve as building materials for the cell or for the whole organism. The Best example is cellulose. wood is mostly cellulose plant cell with cell wall individual cellulose molecules close-up of cell wall bundle of cellulose molecules cellulose fiber Cellulose Cellulose is a structural polysaccharide composed entirely of glucose monomers. Cellulose is commonly known as fiber. Cellulose is the most abundant organic compound on Earth; because it is the main component of the cell wall of plants. Most animals (including humans) do not have enzymes that can hydrolyze the glucose links in cellulose. Cellulose in our food passes through the digestive tract and is eliminated in feces as “insoluble fiber”. Nevertheless, as fiber travels through the digestive tract, it abrades the intestinal walls and stimulates the secretion of mucus which helps digestion and excretion. Cellulose, even though insoluble, is used by many animals as a source of nourishment. Ruminants (cows, sheep, goats, deer, antelopes, bison, giraffes) first soften this plantbased food in their rumen or first stomach, and regurgitated and re-chewed (“chewing their cud”) – yum! The mass is re-ingested and broken down by microbes that are able to break down the cellulose Another important structural polysaccharide is chitin, used in the exoskeletons of arthropods (including insects, spiders, and crustaceans). Chitin also forms the structural support for the cell walls of many fungi.