Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download What is lactose?
Document related concepts
Transcript
Biomolecules Carbohydrates • Carbon, hydrogen, oxygen, and nitrogen make up the bulk of living matter, but there are other elements necessary for life • Organic molecules are characterized by having a central “backbone” made of atoms of carbon linked to each other like a “chain” of carbon atoms. Other atoms can link to the carbon backbone • There are 4 main types of biomolecules: Carbohydrates Lipids Proteins Nucleic Acids. How do we build large molecules? • Most of the large molecules in living things are macromolecules called polymers • Polymers are long chains of smaller molecular units called monomers • A huge number of different polymers can be made from a small number of monomers • Cells link monomers to form polymers by dehydration synthesis 1 2 3 Short polymer Unlinked monomer Removal of water molecule 2 1 3 Longer polymer 4 • Polymers are broken down to monomers by the reverse process, hydrolysis 1 2 3 4 Addition of water molecule 1 2 3 Coating of capture strand Figure 3.3B 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 • These molecules typically have a formula that is a multiple of CH2O (examples) • Monosaccharides are the fuels for cellular work. • Many monosaccharides form rings, as shown here for glucose • Many monosaccharides form rings, as shown here for glucose Abbreviated structure Figure 3.4C Examples of 6 C Monosaccharides H C O H C OH HO C H CH2OH 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 CH2OH CH2OH 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 Energy Glucose + Glucose H2O Maltose Enzyme Enzyme Energy H2O Energy H2O Disaccharides Store Energy and Serve As Building Blocks Glucose + Fructose Energy 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 – eta 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 Æ 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 ÖStorage Polysaccharides: They store energy ÖStructural 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, especially parts rich in starch, can also access this starch to support their own metabolism. 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 but only have about a one day supply. Insert Fig. 5.6b - glycogen •Other polysaccharides, structural polysaccharides serve as building materials for the cell or whole organism. This is the case of cellulose commonly known as fiber. Cellulose is the main component of the cell wall of plants. wood is mostly cellulose plant cell with cell wall close-up of cell wall individual cellulose molecules bundle of cellulose molecules cellulose fiber • The enzymes in our body cannot hydrolyze the bonds in cellulose. • Cellulose in our food passes through the digestive tract and is eliminated in feces as “insoluble fiber”. • As it travels through the digestive tract, it abrades the intestinal walls and stimulates the secretion of mucus. • Some microbes can digest cellulose to its glucose monomers through the use of cellulase enzymes. • Many eukaryotic herbivores, like cows and termites, have symbiotic relationships with cellulolytic microbes, allowing them access to this rich source of energy. • 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.
