Presentation on theme: "Carbon Compounds The structure of a biomolecule will help determine its properties and functions Organic compounds contain carbon atoms that are covalently."— Presentation transcript:
Carbon Compounds The structure of a biomolecule will help determine its properties and functions Organic compounds contain carbon atoms that are covalently bonded to other elements All organic molecules contain the element carbon. All living things are composed of water, and organic molecules. The carbohydrates are the most abundant of the four groups of organic molecules. Carbon is a special element, because it has four electrons in its valence level to share. It can form four covalent bonds because of this.
The simplest organic compounds contain molecules composed of carbon and hydrogen…also known as “hydrocarbons”. The compound methane contains one carbon bonded to four hydrogens. In chemistry we use a molecular formula to show how many atoms of each element are present in a molecule. A molecular formula does not show the structure of the molecule. Scientists often use structural formulas to show the number and arrangement of atoms in a compounds. CH 4 Fossil Fuels are hydrocarbons.
Carbohydrates are biomolecules that are composed of carbon, hydrogen, and oxygen in approximately a ratio of 1:2:1 Carbohydrates include sugars (monosaccharides, and disaccharides) starches (polysaccharides), and complex polysaccharides like cellulose and glycogen.
a key source of energy found in most foods especially fruits, vegetables, and grains The building blocks of carbohydrates are single sugars called monosaccharides
Sugars Monosaccharides- single sugars –Glucose C 6 H 12 O 6 –Fructose Disaccharides- double sugars –Sucrose ( table sugar) Polysaccharides- three or more monosaccharides –Macromolecule –Starch –Glycogen –Cellulose- provides structure for plants (humans cannot digest)
Glucose and other monosaccharides often form ring structures The ring forms when a hydrogen is transferred from the hydroxyl group on the #5 carbon to the oxygen of the carbonyl group on the #1 carbon. #5 #1 This allows the #1 carbon to form a bond with the oxygen attached to the #5 carbon, completing the ring.
Two [or more] monosaccharides may be joined by dehydration synthesis to produce larger disaccharides and polysaccharides. The reverse reaction of breaking up polymers is accomplished by another chemical reaction known as hydrolysis. Hydrolysis is simply the reverse of dehydration synthesis. You add water to a molecule to break it down. X + H 2 O --> HX + OH XOH + HZ XZ + HOH Dehydration means to take water out. When dehydration synthesis occurs, something is being built, while taking water out, or producing water as a product. Dehydration synthesis is a typical condensation reaction. Glucose is a very common monosaccharide that is used for cellular respiration among other things. The names of most sugars end in –ose. The carbon skeletons of monosaccharides are usually 3-7 carbon atoms long. Glucose and fructose are hexoses (six-carbons long), pentoses have five carbons, and trioses have three carbons.
Two glucose molecules can be joined to produce a molecule of maltose [and a molecule of water]. A second disaccharide, the common table sugar known as sucrose, is produced by combining glucose and fructose. If dehydration synthesis continues for a long time, a long and complex carbohydrate chain called a polysaccharide is formed. A glycosidic link occurs when two monosaccharides are joined by dehydration synthesis.
Polysaccharides are produced by adding more monosaccharides to the chain. Some of the most important polysaccharides are made of long polymers of glucose. In glycogen, or animal starch, the glucose units are again joined to produce long chains, but side chains are linked to the main chain. What element can be found at each corner in the ring?
Storage Polysaccharides Starch –Is a polymer consisting entirely of glucose monomers –Is the major storage form of glucose in plants Chloroplast Starch Amylose Amylopectin 1 m
Mitochondria Giycogen granules 0.5 m Glycogen Glycogen is the storage form of glucose in animals and humans which is analogous to the starch in plants. Glycogen is synthesized and stored mainly in the liver and the muscles Plants make glucose and cellulose through the photosynthesis processes, and store starch primarily in their roots. Animals and human in turn eat plant materials and products. Digestion is a process of hydrolysis where the starch is broken down into the various monosaccharides. A major product is glucose, which can be used immediately for metabolism to make energy, through the process of cellular respiration. The glucose that is not used immediately is converted in the liver and muscles into glycogen for storage. Any glucose in excess of the needs for energy and storage as glycogen is converted to fat.
Another polysaccharide, cellulose, has its glucose units joined together, however, alternating glucose units are 'flip- flopped'. Cellulose is found in plant cells, and forms the structurally strong framework in the cell wall. It’s lattice-like structure makes it very strong indeed. Changes in the bond configuration cause changes in the final shape and function of the molecules.
Cellulose is difficult to digest –Cows and other herbivores have microbes in their stomachs to facilitate this process Humans do not!
Chitin, another important structural polysaccharide –Is found in the exoskeleton of arthropods –Can be used as surgical thread (a) The structure of the chitin monomer. O CH 2 O H OH H H H NH C CH 3 O H H (b) Chitin forms the exoskeleton of arthropods. This cicada is molting, shedding its old exoskeleton and emerging in adult form. (c) Chitin is used to make a strong and flexible surgical thread that decomposes after the wound or incision heals. OH