Saccharides Packet #9 Chapter #5 11/11/2018 8:46:57 AM

General Characteristics

Introduction Saccharides are mainly used for energy and are also known as starches or sugars. Empirical Formula CnH2nOn When n = 3 Called a triose sugar When n = 5 Called a pentose sugar When n = 6 Called a hexose sugar 11/11/2018 8:46:57 AM

Isomers of Saccharides

Isomers There are two forms in which a triose, pentose and hexose can exist. Aldose Ketose An aldose sugar is identified by the presence of the functional group called the aldehyde. A ketose sugar is identified by the presence of the functional group called the ketone. 11/11/2018 8:46:57 AM

Monosaccharides

Monosaccharides Introduction

Monosaccharide The “single” form of a sugar Has basic formula C6H12O6 All reduce Benedict’s reagent A solution of sodium citrate, sodium carbonate, and copper sulfate that changes from blue to yellow or red in the presence of reducing sugars, such as glucose. Sweet Soluble Easily transported Main respiratory substrates. 11/11/2018 8:46:57 AM

Monosaccharides Triose Sugars

Trioses Glyceraldehyde Dihydroxacetone Aldose sugar The phosphorylated form is the first formed sugar in photosynthesis May be used as a respiratory substrate or converted to starch for storage Intermediate in the Kreb’s Cycle (Cell Respiration) Dihydroxacetone Ketose sugar Respiratory substrate Intermediate in the Kreb’s Cycle 11/11/2018 8:46:57 AM

Monosaccharides Pentose Sugars

Pentose Sugars Ribose/Deoxyribose Aldose sugars Make up part of nucleotides Gives structural support to the nucleic acids RNA & DNA Component of hydrogen carrier NAD NADP FAD Component of ATP 11/11/2018 8:46:57 AM

Pentose Sugars Ribulose Ketose sugar Carbon dioxide acceptor in photosynthesis 11/11/2018 8:46:57 AM

Monosaccharides Hexose Sugars

Hexose Sugars Glucose Aldose sugar The presence of all the oxygen molecules ensure that glucose is strongly hydrophilic Remember, that oxygen is very electronegative and helps increase the polarity of an atom Contains a lot of energy within it’s chemical bonds

Linear & Ring Structures of Glucose

Ring Structures of Glucose Glucose, when in a ring form, can exist in two different forms (isomers) α glucose β glucose

Hexose Sugars Galactose Fructose Aldose sugar Respiratory substrate Used in the synthesis of lactose Fructose Ketose sugar Used in the synthesis of insulin Component of nectar Sweetens fruits to attract animals to aid in seed dispersal 11/11/2018 8:46:57 AM

Monosaccharides

Polymerization The process of joining monomers to form polymers.

Polymerization Monosaccharides, a monomer, and other organic compounds, can be combined/linked together by a chemical process known as polymerization to form polymers. Di-saccharides Occurs when two monosaccharides are joined together. Polysaccharide Occurs when many monosaccharides are joined together. 11/11/2018 8:46:57 AM

Polymerization Polymerization can occur via a dehydration synthesis/condensation chemical reaction. Water is a by-product of the chemical reaction.

Polymerization

Disaccharides Characteristics

Disaccharides Formed by the condensation of any two monosaccharide Basic chemical formula C12H24O12 Some reduce in Benedict’s solution Maltose Others are non-reducing sugars Sucrose All are sweet, soluble in water and are readily converted into monosaccharides by the addition of a water molecule Hydrolysis 11/11/2018 8:46:57 AM

Disaccharides Examples

Disaccharides Sucrose (Cane sugar) Lactose (Milk Sugar) Glucose+ Fructose Respiratory substrate The form in which most carbohydrates are transported in plants Storage material in some plants Allium – onions Non-reducing sugar Lactose (Milk Sugar) Glucose + Galactose Mammalian milk contains 5% lactose Major carbohydrate source for sucklings Maltose (Malt sugar) Glucose + Glucose Reduce in Benedit’s solution 11/11/2018 8:46:57 AM

Polysaccharides

Introduction Vast majority of carbohydrates in nature are found in the form of very large polymers made up by the joining of various monosaccharides. Glucose is the most abundant sugar used in making these large polymers Most polysaccharides are polydisperse Even when in a pure form, any given sample of the substance will vary in its size and the number of monomer units in its structure For example, starch may have any where between 100 and 10,000 glucose monomers in a chain

Starch Starch Made by plants as a way of storing chemical energy Major storage carbohydrate in plants Comes in two forms Amylose Amylopectin 11/11/2018 8:46:57 AM

Amylose Amylose Long unbranched chain of -glucose molecules

Amylopectin Contains unbranched chain of -glucose with 1,4 glycosidic links Plus branched chain of -glucose units with 1,4 and 1,6 glucosidic links Branches occur every20-24 units 11/11/2018 8:46:57 AM

Cellulose I Probably* the most prevalent and abundant source in nature Possible that 50% of all of the organic carbon, on the planet, is in the form of glucose Most commonly found in plants Gives structural support to cell walls Is in its purest form in cotton Homework What are the advantages of cotton containing 90% cellulose?

Cellulose II Formed when -glucose molecules are joined together using their 1st and 4thcarbons Unbranched chain of -glucose units with 1,4 glycosidic links + cross bridges Reaches lengths of between 300 and over 2000 units

Glycogen Animal equivalent of starch Branched molecule Major storage carbohydrate in animals and fungi Found in the liver and muscles Branched molecule Highly branched chains of -glucose units with 1,4 glycosidic links New branch occurring every 10 or so units along the chain 11/11/2018 8:46:57 AM

Chitin A tough, protective, semitransparent substance, primarily a nitrogen-containing polysaccharide, forming the principal component of arthropod exoskeletons and the cell walls of certain fungi. Forms the basis of the hard shells of crustaceans Crab; lobster; shrimp

Chitin II Long unbranched molecule consisting of -glucose molecules are joined together using their 1st and 4thcarbons May be thought of as cellulose in which the hydroxyl groups on the second carbon are replaced with NHCOCH3 groups